diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-05-06 13:50:15 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-05-06 13:50:15 -0700 |
| commit | 007dc78fea62610bf06829e38f1d8c69b6ea5af6 (patch) | |
| tree | 683af90696ed7a237dedd48030bfd649e5822955 | |
| parent | 2f1835dffa949f560dfa3ed63c0bfc10944b461c (diff) | |
| parent | d671002be6bdd7f77a771e23bf3e95d1f16775e6 (diff) | |
Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
"Here are the locking changes in this cycle:
- rwsem unification and simpler micro-optimizations to prepare for
more intrusive (and more lucrative) scalability improvements in
v5.3 (Waiman Long)
- Lockdep irq state tracking flag usage cleanups (Frederic
Weisbecker)
- static key improvements (Jakub Kicinski, Peter Zijlstra)
- misc updates, cleanups and smaller fixes"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (26 commits)
locking/lockdep: Remove unnecessary unlikely()
locking/static_key: Don't take sleeping locks in __static_key_slow_dec_deferred()
locking/static_key: Factor out the fast path of static_key_slow_dec()
locking/static_key: Add support for deferred static branches
locking/lockdep: Test all incompatible scenarios at once in check_irq_usage()
locking/lockdep: Avoid bogus Clang warning
locking/lockdep: Generate LOCKF_ bit composites
locking/lockdep: Use expanded masks on find_usage_*() functions
locking/lockdep: Map remaining magic numbers to lock usage mask names
locking/lockdep: Move valid_state() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING
locking/rwsem: Prevent unneeded warning during locking selftest
locking/rwsem: Optimize rwsem structure for uncontended lock acquisition
locking/rwsem: Enable lock event counting
locking/lock_events: Don't show pvqspinlock events on bare metal
locking/lock_events: Make lock_events available for all archs & other locks
locking/qspinlock_stat: Introduce generic lockevent_*() counting APIs
locking/rwsem: Enhance DEBUG_RWSEMS_WARN_ON() macro
locking/rwsem: Add debug check for __down_read*()
locking/rwsem: Micro-optimize rwsem_try_read_lock_unqueued()
locking/rwsem: Move rwsem internal function declarations to rwsem-xadd.h
...
62 files changed, 983 insertions, 1925 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index 52cd9341e03c..7be412e1a380 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9100,7 +9100,6 @@ F: arch/*/include/asm/spinlock*.h F: include/linux/rwlock*.h F: include/linux/mutex*.h F: include/linux/rwsem*.h -F: arch/*/include/asm/rwsem.h F: include/linux/seqlock.h F: lib/locking*.[ch] F: kernel/locking/ diff --git a/arch/Kconfig b/arch/Kconfig index a826843470ed..3ab446bd12ef 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -907,6 +907,15 @@ config HAVE_ARCH_PREL32_RELOCATIONS config ARCH_USE_MEMREMAP_PROT bool +config LOCK_EVENT_COUNTS + bool "Locking event counts collection" + depends on DEBUG_FS + ---help--- + Enable light-weight counting of various locking related events + in the system with minimal performance impact. This reduces + the chance of application behavior change because of timing + differences. The counts are reported via debugfs. + source "kernel/gcov/Kconfig" source "scripts/gcc-plugins/Kconfig" diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index c7c976eb6407..f7b19b813a70 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -50,13 +50,6 @@ config MMU bool default y -config RWSEM_GENERIC_SPINLOCK - bool - -config RWSEM_XCHGADD_ALGORITHM - bool - default y - config ARCH_HAS_ILOG2_U32 bool default n diff --git a/arch/alpha/include/asm/rwsem.h b/arch/alpha/include/asm/rwsem.h deleted file mode 100644 index cf8fc8f9a2ed..000000000000 --- a/arch/alpha/include/asm/rwsem.h +++ /dev/null @@ -1,211 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -#ifndef _ALPHA_RWSEM_H -#define _ALPHA_RWSEM_H - -/* - * Written by Ivan Kokshaysky <ink@jurassic.park.msu.ru>, 2001. - * Based on asm-alpha/semaphore.h and asm-i386/rwsem.h - */ - -#ifndef _LINUX_RWSEM_H -#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead" -#endif - -#ifdef __KERNEL__ - -#include <linux/compiler.h> - -#define RWSEM_UNLOCKED_VALUE 0x0000000000000000L -#define RWSEM_ACTIVE_BIAS 0x0000000000000001L -#define RWSEM_ACTIVE_MASK 0x00000000ffffffffL -#define RWSEM_WAITING_BIAS (-0x0000000100000000L) -#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS -#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) - -static inline int ___down_read(struct rw_semaphore *sem) -{ - long oldcount; -#ifndef CONFIG_SMP - oldcount = sem->count.counter; - sem->count.counter += RWSEM_ACTIVE_READ_BIAS; -#else - long temp; - __asm__ __volatile__( - "1: ldq_l %0,%1\n" - " addq %0,%3,%2\n" - " stq_c %2,%1\n" - " beq %2,2f\n" - " mb\n" - ".subsection 2\n" - "2: br 1b\n" - ".previous" - :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp) - :"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory"); -#endif - return (oldcount < 0); -} - -static inline void __down_read(struct rw_semaphore *sem) -{ - if (unlikely(___down_read(sem))) - rwsem_down_read_failed(sem); -} - -static inline int __down_read_killable(struct rw_semaphore *sem) -{ - if (unlikely(___down_read(sem))) - if (IS_ERR(rwsem_down_read_failed_killable(sem))) - return -EINTR; - - return 0; -} - -/* - * trylock for reading -- returns 1 if successful, 0 if contention - */ -static inline int __down_read_trylock(struct rw_semaphore *sem) -{ - long old, new, res; - - res = atomic_long_read(&sem->count); - do { - new = res + RWSEM_ACTIVE_READ_BIAS; - if (new <= 0) - break; - old = res; - res = atomic_long_cmpxchg(&sem->count, old, new); - } while (res != old); - return res >= 0 ? 1 : 0; -} - -static inline long ___down_write(struct rw_semaphore *sem) -{ - long oldcount; -#ifndef CONFIG_SMP - oldcount = sem->count.counter; - sem->count.counter += RWSEM_ACTIVE_WRITE_BIAS; -#else - long temp; - __asm__ __volatile__( - "1: ldq_l %0,%1\n" - " addq %0,%3,%2\n" - " stq_c %2,%1\n" - " beq %2,2f\n" - " mb\n" - ".subsection 2\n" - "2: br 1b\n" - ".previous" - :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp) - :"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory"); -#endif - return oldcount; -} - -static inline void __down_write(struct rw_semaphore *sem) -{ - if (unlikely(___down_write(sem))) - rwsem_down_write_failed(sem); -} - -static inline int __down_write_killable(struct rw_semaphore *sem) -{ - if (unlikely(___down_write(sem))) { - if (IS_ERR(rwsem_down_write_failed_killable(sem))) - return -EINTR; - } - - return 0; -} - -/* - * trylock for writing -- returns 1 if successful, 0 if contention - */ -static inline int __down_write_trylock(struct rw_semaphore *sem) -{ - long ret = atomic_long_cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE, - RWSEM_ACTIVE_WRITE_BIAS); - if (ret == RWSEM_UNLOCKED_VALUE) - return 1; - return 0; -} - -static inline void __up_read(struct rw_semaphore *sem) -{ - long oldcount; -#ifndef CONFIG_SMP - oldcount = sem->count.counter; - sem->count.counter -= RWSEM_ACTIVE_READ_BIAS; -#else - long temp; - __asm__ __volatile__( - " mb\n" - "1: ldq_l %0,%1\n" - " subq %0,%3,%2\n" - " stq_c %2,%1\n" - " beq %2,2f\n" - ".subsection 2\n" - "2: br 1b\n" - ".previous" - :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp) - :"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory"); -#endif - if (unlikely(oldcount < 0)) - if ((int)oldcount - RWSEM_ACTIVE_READ_BIAS == 0) - rwsem_wake(sem); -} - -static inline void __up_write(struct rw_semaphore *sem) -{ - long count; -#ifndef CONFIG_SMP - sem->count.counter -= RWSEM_ACTIVE_WRITE_BIAS; - count = sem->count.counter; -#else - long temp; - __asm__ __volatile__( - " mb\n" - "1: ldq_l %0,%1\n" - " subq %0,%3,%2\n" - " stq_c %2,%1\n" - " beq %2,2f\n" - " subq %0,%3,%0\n" - ".subsection 2\n" - "2: br 1b\n" - ".previous" - :"=&r" (count), "=m" (sem->count), "=&r" (temp) - :"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory"); -#endif - if (unlikely(count)) - if ((int)count == 0) - rwsem_wake(sem); -} - -/* - * downgrade write lock to read lock - */ -static inline void __downgrade_write(struct rw_semaphore *sem) -{ - long oldcount; -#ifndef CONFIG_SMP - oldcount = sem->count.counter; - sem->count.counter -= RWSEM_WAITING_BIAS; -#else - long temp; - __asm__ __volatile__( - "1: ldq_l %0,%1\n" - " addq %0,%3,%2\n" - " stq_c %2,%1\n" - " beq %2,2f\n" - " mb\n" - ".subsection 2\n" - "2: br 1b\n" - ".previous" - :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp) - :"Ir" (-RWSEM_WAITING_BIAS), "m" (sem->count) : "memory"); -#endif - if (unlikely(oldcount < 0)) - rwsem_downgrade_wake(sem); -} - -#endif /* __KERNEL__ */ -#endif /* _ALPHA_RWSEM_H */ diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig index c781e45d1d99..23e063df5d2c 100644 --- a/arch/arc/Kconfig +++ b/arch/arc/Kconfig @@ -63,9 +63,6 @@ config SCHED_OMIT_FRAME_POINTER config GENERIC_CSUM def_bool y -config RWSEM_GENERIC_SPINLOCK - def_bool y - config ARCH_DISCONTIGMEM_ENABLE def_bool n diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 9aed25a6019b..dc9855c4a3b4 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -178,10 +178,6 @@ config TRACE_IRQFLAGS_SUPPORT bool default !CPU_V7M -config RWSEM_XCHGADD_ALGORITHM - bool - default y - config ARCH_HAS_ILOG2_U32 bool diff --git a/arch/arm/include/asm/Kbuild b/arch/arm/include/asm/Kbuild index a8a4eb7f6dae..8fb51b7bf1d5 100644 --- a/arch/arm/include/asm/Kbuild +++ b/arch/arm/include/asm/Kbuild @@ -12,7 +12,6 @@ generic-y += mm-arch-hooks.h generic-y += msi.h generic-y += parport.h generic-y += preempt.h -generic-y += rwsem.h generic-y += seccomp.h generic-y += segment.h generic-y += serial.h diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 78d9fafac983..d81adca1b04d 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -236,9 +236,6 @@ config LOCKDEP_SUPPORT config TRACE_IRQFLAGS_SUPPORT def_bool y -config RWSEM_XCHGADD_ALGORITHM - def_bool y - config GENERIC_BUG def_bool y depends on BUG diff --git a/arch/arm64/include/asm/Kbuild b/arch/arm64/include/asm/Kbuild index 1e17ea5c372b..60a933b07001 100644 --- a/arch/arm64/include/asm/Kbuild +++ b/arch/arm64/include/asm/Kbuild @@ -16,7 +16,6 @@ generic-y += mm-arch-hooks.h generic-y += msi.h generic-y += qrwlock.h generic-y += qspinlock.h -generic-y += rwsem.h generic-y += segment.h generic-y += serial.h generic-y += set_memory.h diff --git a/arch/c6x/Kconfig b/arch/c6x/Kconfig index 3bb75e674161..eeb0471268a0 100644 --- a/arch/c6x/Kconfig +++ b/arch/c6x/Kconfig @@ -28,9 +28,6 @@ config MMU config FPU def_bool n -config RWSEM_GENERIC_SPINLOCK - def_bool y - config GENERIC_CALIBRATE_DELAY def_bool y diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig index 725a115759c9..6555d1781132 100644 --- a/arch/csky/Kconfig +++ b/arch/csky/Kconfig @@ -92,9 +92,6 @@ config GENERIC_HWEIGHT config MMU def_bool y -config RWSEM_GENERIC_SPINLOCK - def_bool y - config STACKTRACE_SUPPORT def_bool y diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig index c071da34e081..61c01db6c292 100644 --- a/arch/h8300/Kconfig +++ b/arch/h8300/Kconfig @@ -27,9 +27,6 @@ config H8300 config CPU_BIG_ENDIAN def_bool y -config RWSEM_GENERIC_SPINLOCK - def_bool y - config GENERIC_HWEIGHT def_bool y diff --git a/arch/hexagon/Kconfig b/arch/hexagon/Kconfig index ac441680dcc0..3e54a53208d5 100644 --- a/arch/hexagon/Kconfig +++ b/arch/hexagon/Kconfig @@ -65,12 +65,6 @@ config GENERIC_CSUM config GENERIC_IRQ_PROBE def_bool y -config RWSEM_GENERIC_SPINLOCK - def_bool n - -config RWSEM_XCHGADD_ALGORITHM - def_bool y - config GENERIC_HWEIGHT def_bool y diff --git a/arch/hexagon/include/asm/Kbuild b/arch/hexagon/include/asm/Kbuild index d046e8ccdf78..3ff5f297acda 100644 --- a/arch/hexagon/include/asm/Kbuild +++ b/arch/hexagon/include/asm/Kbuild @@ -27,7 +27,6 @@ generic-y += mm-arch-hooks.h generic-y += pci.h generic-y += percpu.h generic-y += preempt.h -generic-y += rwsem.h generic-y += sections.h generic-y += segment.h generic-y += serial.h diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig index 8d7396bd1790..73a26f04644e 100644 --- a/arch/ia64/Kconfig +++ b/arch/ia64/Kconfig @@ -83,10 +83,6 @@ config STACKTRACE_SUPPORT config GENERIC_LOCKBREAK def_bool n -config RWSEM_XCHGADD_ALGORITHM - bool - default y - config HUGETLB_PAGE_SIZE_VARIABLE bool depends on HUGETLB_PAGE diff --git a/arch/ia64/include/asm/rwsem.h b/arch/ia64/include/asm/rwsem.h deleted file mode 100644 index 917910607e0e..000000000000 --- a/arch/ia64/include/asm/rwsem.h +++ /dev/null @@ -1,172 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -/* - * R/W semaphores for ia64 - * - * Copyright (C) 2003 Ken Chen <kenneth.w.chen@intel.com> - * Copyright (C) 2003 Asit Mallick <asit.k.mallick@intel.com> - * Copyright (C) 2005 Christoph Lameter <cl@linux.com> - * - * Based on asm-i386/rwsem.h and other architecture implementation. - * - * The MSW of the count is the negated number of active writers and - * waiting lockers, and the LSW is the total number of active locks. - * - * The lock count is initialized to 0 (no active and no waiting lockers). - * - * When a writer subtracts WRITE_BIAS, it'll get 0xffffffff00000001 for - * the case of an uncontended lock. Readers increment by 1 and see a positive - * value when uncontended, negative if there are writers (and maybe) readers - * waiting (in which case it goes to sleep). - */ - -#ifndef _ASM_IA64_RWSEM_H -#define _ASM_IA64_RWSEM_H - -#ifndef _LINUX_RWSEM_H -#error "Please don't include <asm/rwsem.h> directly, use <linux/rwsem.h> instead." -#endif - -#include <asm/intrinsics.h> - -#define RWSEM_UNLOCKED_VALUE __IA64_UL_CONST(0x0000000000000000) -#define RWSEM_ACTIVE_BIAS (1L) -#define RWSEM_ACTIVE_MASK (0xffffffffL) -#define RWSEM_WAITING_BIAS (-0x100000000L) -#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS -#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) - -/* - * lock for reading - */ -static inline int -___down_read (struct rw_semaphore *sem) -{ - long result = ia64_fetchadd8_acq((unsigned long *)&sem->count.counter, 1); - - return (result < 0); -} - -static inline void -__down_read (struct rw_semaphore *sem) -{ - if (___down_read(sem)) - rwsem_down_read_failed(sem); -} - -static inline int -__down_read_killable (struct rw_semaphore *sem) -{ - if (___down_read(sem)) - if (IS_ERR(rwsem_down_read_failed_killable(sem))) - return -EINTR; - - return 0; -} - -/* - * lock for writing - */ -static inline long -___down_write (struct rw_semaphore *sem) -{ - long old, new; - - do { - old = atomic_long_read(&sem->count); - new = old + RWSEM_ACTIVE_WRITE_BIAS; - } while (atomic_long_cmpxchg_acquire(&sem->count, old, new) != old); - - return old; -} - -static inline void -__down_write (struct rw_semaphore *sem) -{ - if (___down_write(sem)) - rwsem_down_write_failed(sem); -} - -static inline int -__down_write_killable (struct rw_semaphore *sem) -{ - if (___down_write(sem)) { - if (IS_ERR(rwsem_down_write_failed_killable(sem))) - return -EINTR; - } - - return 0; -} - -/* - * unlock after reading - */ -static inline void -__up_read (struct rw_semaphore *sem) -{ - long result = ia64_fetchadd8_rel((unsigned long *)&sem->count.counter, -1); - - if (result < 0 && (--result & RWSEM_ACTIVE_MASK) == 0) - rwsem_wake(sem); -} - -/* - * unlock after writing - */ -static inline void -__up_write (struct rw_semaphore *sem) -{ - long old, new; - - do { - old = atomic_long_read(&sem->count); - new = old - RWSEM_ACTIVE_WRITE_BIAS; - } while (atomic_long_cmpxchg_release(&sem->count, old, new) != old); - - if (new < 0 && (new & RWSEM_ACTIVE_MASK) == 0) - rwsem_wake(sem); -} - -/* - * trylock for reading -- returns 1 if successful, 0 if contention - */ -static inline int -__down_read_trylock (struct rw_semaphore *sem) -{ - long tmp; - while ((tmp = atomic_long_read(&sem->count)) >= 0) { - if (tmp == atomic_long_cmpxchg_acquire(&sem->count, tmp, tmp+1)) { - return 1; - } - } - return 0; -} - -/* - * trylock for writing -- returns 1 if successful, 0 if contention - */ -static inline int -__down_write_trylock (struct rw_semaphore *sem) -{ - long tmp = atomic_long_cmpxchg_acquire(&sem->count, - RWSEM_UNLOCKED_VALUE, RWSEM_ACTIVE_WRITE_BIAS); - return tmp == RWSEM_UNLOCKED_VALUE; -} - -/* - * downgrade write lock to read lock - */ -static inline void -__downgrade_write (struct rw_semaphore *sem) -{ - long old, new; - - do { - old = atomic_long_read(&sem->count); - new = old - RWSEM_WAITING_BIAS; - } while (atomic_long_cmpxchg_release(&sem->count, old, new) != old); - - if (old < 0) - rwsem_downgrade_wake(sem); -} - -#endif /* _ASM_IA64_RWSEM_H */ diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig index 4e37efbc9296..735b9679fe6f 100644 --- a/arch/m68k/Kconfig +++ b/arch/m68k/Kconfig @@ -33,13 +33,6 @@ config M68K config CPU_BIG_ENDIAN def_bool y -config RWSEM_GENERIC_SPINLOCK - bool - default y - -config RWSEM_XCHGADD_ALGORITHM - bool - config ARCH_HAS_ILOG2_U32 bool diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig index 321e398ab6b5..adb179f519f9 100644 --- a/arch/microblaze/Kconfig +++ b/arch/microblaze/Kconfig @@ -59,15 +59,9 @@ config CPU_LITTLE_ENDIAN endchoice -config RWSEM_GENERIC_SPINLOCK - def_bool y - config ZONE_DMA def_bool y -config RWSEM_XCHGADD_ALGORITHM - bool - config ARCH_HAS_ILOG2_U32 def_bool n diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 4a5f5b0ee9a9..b9c48b27162d 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -1037,13 +1037,6 @@ source "arch/mips/paravirt/Kconfig" endmenu -config RWSEM_GENERIC_SPINLOCK - bool - default y - -config RWSEM_XCHGADD_ALGORITHM - bool - config GENERIC_HWEIGHT bool default y diff --git a/arch/nds32/Kconfig b/arch/nds32/Kconfig index addb7f5f5264..55559ca0efe4 100644 --- a/arch/nds32/Kconfig +++ b/arch/nds32/Kconfig @@ -60,9 +60,6 @@ config GENERIC_LOCKBREAK def_bool y depends on PREEMPT -config RWSEM_GENERIC_SPINLOCK - def_bool y - config TRACE_IRQFLAGS_SUPPORT def_bool y diff --git a/arch/nios2/Kconfig b/arch/nios2/Kconfig index 3633f8144367..ea37394ff3ea 100644 --- a/arch/nios2/Kconfig +++ b/arch/nios2/Kconfig @@ -41,9 +41,6 @@ config NO_IOPORT_MAP config FPU def_bool n -config RWSEM_GENERIC_SPINLOCK - def_bool y - config TRACE_IRQFLAGS_SUPPORT def_bool n diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig index c6cf8a49a0ab..7cfb20555b10 100644 --- a/arch/openrisc/Kconfig +++ b/arch/openrisc/Kconfig @@ -44,12 +44,6 @@ config CPU_BIG_ENDIAN config MMU def_bool y -config RWSEM_GENERIC_SPINLOCK - def_bool y - -config RWSEM_XCHGADD_ALGORITHM - def_bool n - config GENERIC_HWEIGHT def_bool y diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig index c8e621296092..f1ed8ddfe486 100644 --- a/arch/parisc/Kconfig +++ b/arch/parisc/Kconfig @@ -75,12 +75,6 @@ config GENERIC_LOCKBREAK default y depends on SMP && PREEMPT -config RWSEM_GENERIC_SPINLOCK - def_bool y - -config RWSEM_XCHGADD_ALGORITHM - bool - config ARCH_HAS_ILOG2_U32 bool default n diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 8e1e2abf17eb..fab0bf4259c7 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -103,13 +103,6 @@ config LOCKDEP_SUPPORT bool default y -config RWSEM_GENERIC_SPINLOCK - bool - -config RWSEM_XCHGADD_ALGORITHM - bool - default y - config GENERIC_LOCKBREAK bool default y diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild index a0c132bedfae..36bda391e549 100644 --- a/arch/powerpc/include/asm/Kbuild +++ b/arch/powerpc/include/asm/Kbuild @@ -8,6 +8,5 @@ generic-y += irq_regs.h generic-y += local64.h generic-y += mcs_spinlock.h generic-y += preempt.h -generic-y += rwsem.h generic-y += vtime.h generic-y += msi.h diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index eb56c82d8aa1..0582260fb6c2 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -69,9 +69,6 @@ config STACKTRACE_SUPPORT config TRACE_IRQFLAGS_SUPPORT def_bool y -config RWSEM_GENERIC_SPINLOCK - def_bool y - config GENERIC_BUG def_bool y depends on BUG diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index cf06e313e103..97b555e772d7 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -14,12 +14,6 @@ config LOCKDEP_SUPPORT config STACKTRACE_SUPPORT def_bool y -config RWSEM_GENERIC_SPINLOCK - bool - -config RWSEM_XCHGADD_ALGORITHM - def_bool y - config ARCH_HAS_ILOG2_U32 def_bool n diff --git a/arch/s390/include/asm/Kbuild b/arch/s390/include/asm/Kbuild index 12d77cb11fe5..d5fadefea33c 100644 --- a/arch/s390/include/asm/Kbuild +++ b/arch/s390/include/asm/Kbuild @@ -20,7 +20,6 @@ generic-y += local.h generic-y += local64.h generic-y += mcs_spinlock.h generic-y += mm-arch-hooks.h -generic-y += rwsem.h generic-y += trace_clock.h generic-y += unaligned.h generic-y += word-at-a-time.h diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig index b1c91ea9a958..0be08d586d40 100644 --- a/arch/sh/Kconfig +++ b/arch/sh/Kconfig @@ -90,12 +90,6 @@ config ARCH_DEFCONFIG default "arch/sh/configs/shx3_defconfig" if SUPERH32 default "arch/sh/configs/cayman_defconfig" if SUPERH64 -config RWSEM_GENERIC_SPINLOCK - def_bool y - -config RWSEM_XCHGADD_ALGORITHM - bool - config GENERIC_BUG def_bool y depends on BUG && SUPERH32 diff --git a/arch/sh/include/asm/Kbuild b/arch/sh/include/asm/Kbuild index 7bf2cb680d32..73fff39a0122 100644 --- a/arch/sh/include/asm/Kbuild +++ b/arch/sh/include/asm/Kbuild @@ -17,7 +17,6 @@ generic-y += mm-arch-hooks.h generic-y += parport.h generic-y += percpu.h generic-y += preempt.h -generic-y += rwsem.h generic-y += serial.h generic-y += sizes.h generic-y += trace_clock.h diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig index db79290ed6d5..f6421c9ce5d3 100644 --- a/arch/sparc/Kconfig +++ b/arch/sparc/Kconfig @@ -192,14 +192,6 @@ config NR_CPUS source "kernel/Kconfig.hz" -config RWSEM_GENERIC_SPINLOCK - bool - default y if SPARC32 - -config RWSEM_XCHGADD_ALGORITHM - bool - default y if SPARC64 - config GENERIC_HWEIGHT bool default y diff --git a/arch/sparc/include/asm/Kbuild b/arch/sparc/include/asm/Kbuild index a22cfd5c0ee8..2ca3200d3616 100644 --- a/arch/sparc/include/asm/Kbuild +++ b/arch/sparc/include/asm/Kbuild @@ -18,7 +18,6 @@ generic-y += mm-arch-hooks.h generic-y += module.h generic-y += msi.h generic-y += preempt.h -generic-y += rwsem.h generic-y += serial.h generic-y += trace_clock.h generic-y += word-at-a-time.h diff --git a/arch/unicore32/Kconfig b/arch/unicore32/Kconfig index d83c8f70900d..2445dfcf6444 100644 --- a/arch/unicore32/Kconfig +++ b/arch/unicore32/Kconfig @@ -39,12 +39,6 @@ config STACKTRACE_SUPPORT config LOCKDEP_SUPPORT def_bool y -config RWSEM_GENERIC_SPINLOCK - def_bool y - -config RWSEM_XCHGADD_ALGORITHM - bool - config ARCH_HAS_ILOG2_U32 bool diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index f1162df4a805..90e2640ade75 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -268,9 +268,6 @@ config ARCH_MAY_HAVE_PC_FDC def_bool y depends on ISA_DMA_API -config RWSEM_XCHGADD_ALGORITHM - def_bool y - config GENERIC_CALIBRATE_DELAY def_bool y @@ -783,14 +780,6 @@ config PARAVIRT_SPINLOCKS If you are unsure how to answer this question, answer Y. -config QUEUED_LOCK_STAT - bool "Paravirt queued spinlock statistics" - depends on PARAVIRT_SPINLOCKS && DEBUG_FS - ---help--- - Enable the collection of statistical data on the slowpath - behavior of paravirtualized queued spinlocks and report - them on debugfs. - source "arch/x86/xen/Kconfig" config KVM_GUEST diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h deleted file mode 100644 index 4c25cf6caefa..000000000000 --- a/arch/x86/include/asm/rwsem.h +++ /dev/null @@ -1,237 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -/* rwsem.h: R/W semaphores implemented using XADD/CMPXCHG for i486+ - * - * Written by David Howells (dhowells@redhat.com). - * - * Derived from asm-x86/semaphore.h - * - * - * The MSW of the count is the negated number of active writers and waiting - * lockers, and the LSW is the total number of active locks - * - * The lock count is initialized to 0 (no active and no waiting lockers). - * - * When a writer subtracts WRITE_BIAS, it'll get 0xffff0001 for the case of an - * uncontended lock. This can be determined because XADD returns the old value. - * Readers increment by 1 and see a positive value when uncontended, negative - * if there are writers (and maybe) readers waiting (in which case it goes to - * sleep). - * - * The value of WAITING_BIAS supports up to 32766 waiting processes. This can - * be extended to 65534 by manually checking the whole MSW rather than relying - * on the S flag. - * - * The value of ACTIVE_BIAS supports up to 65535 active processes. - * - * This should be totally fair - if anything is waiting, a process that wants a - * lock will go to the back of the queue. When the currently active lock is - * released, if there's a writer at the front of the queue, then that and only - * that will be woken up; if there's a bunch of consecutive readers at the - * front, then they'll all be woken up, but no other readers will be. - */ - -#ifndef _ASM_X86_RWSEM_H -#define _ASM_X86_RWSEM_H - -#ifndef _LINUX_RWSEM_H -#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead" -#endif - -#ifdef __KERNEL__ -#include <asm/asm.h> - -/* - * The bias values and the counter type limits the number of - * potential readers/writers to 32767 for 32 bits and 2147483647 - * for 64 bits. - */ - -#ifdef CONFIG_X86_64 -# define RWSEM_ACTIVE_MASK 0xffffffffL -#else -# define RWSEM_ACTIVE_MASK 0x0000ffffL -#endif - -#define RWSEM_UNLOCKED_VALUE 0x00000000L -#define RWSEM_ACTIVE_BIAS 0x00000001L -#define RWSEM_WAITING_BIAS (-RWSEM_ACTIVE_MASK-1) -#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS -#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) - -/* - * lock for reading - */ -#define ____down_read(sem, slow_path) \ -({ \ - struct rw_semaphore* ret; \ - asm volatile("# beginning down_read\n\t" \ - LOCK_PREFIX _ASM_INC "(%[sem])\n\t" \ - /* adds 0x00000001 */ \ - " jns 1f\n" \ - " call " slow_path "\n" \ - "1:\n\t" \ - "# ending down_read\n\t" \ - : "+m" (sem->count), "=a" (ret), \ - ASM_CALL_CONSTRAINT \ - : [sem] "a" (sem) \ - : "memory", "cc"); \ - ret; \ -}) - -static inline void __down_read(struct rw_semaphore *sem) -{ - ____down_read(sem, "call_rwsem_down_read_failed"); -} - -static inline int __down_read_killable(struct rw_semaphore *sem) -{ - if (IS_ERR(____down_read(sem, "call_rwsem_down_read_failed_killable"))) - return -EINTR; - return 0; -} - -/* - * trylock for reading -- returns 1 if successful, 0 if contention - */ -static inline bool __down_read_trylock(struct rw_semaphore *sem) -{ - long result, tmp; - asm volatile("# beginning __down_read_trylock\n\t" - " mov %[count],%[result]\n\t" - "1:\n\t" - " mov %[result],%[tmp]\n\t" - " add %[inc],%[tmp]\n\t" - " jle 2f\n\t" - LOCK_PREFIX " cmpxchg %[tmp],%[count]\n\t" - " jnz 1b\n\t" - "2:\n\t" - "# ending __down_read_trylock\n\t" - : [count] "+m" (sem->count), [result] "=&a" (result), - [tmp] "=&r" (tmp) - : [inc] "i" (RWSEM_ACTIVE_READ_BIAS) - : "memory", "cc"); - return result >= 0; -} - -/* - * lock for writing - */ -#define ____down_write(sem, slow_path) \ -({ \ - long tmp; \ - struct rw_semaphore* ret; \ - \ - asm volatile("# beginning down_write\n\t" \ - LOCK_PREFIX " xadd %[tmp],(%[sem])\n\t" \ - /* adds 0xffff0001, returns the old value */ \ - " test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t" \ - /* was the active mask 0 before? */\ - " jz 1f\n" \ - " call " slow_path "\n" \ - "1:\n" \ - "# ending down_write" \ - : "+m" (sem->count), [tmp] "=d" (tmp), \ - "=a" (ret), ASM_CALL_CONSTRAINT \ - : [sem] "a" (sem), "[tmp]" (RWSEM_ACTIVE_WRITE_BIAS) \ - : "memory", "cc"); \ - ret; \ -}) - -static inline void __down_write(struct rw_semaphore *sem) -{ - ____down_write(sem, "call_rwsem_down_write_failed"); -} - -static inline int __down_write_killable(struct rw_semaphore *sem) -{ - if (IS_ERR(____down_write(sem, "call_rwsem_down_write_failed_killable"))) - return -EINTR; - - return 0; -} - -/* - * trylock for writing -- returns 1 if successful, 0 if contention - */ -static inline bool __down_write_trylock(struct rw_semaphore *sem) -{ - bool result; - long tmp0, tmp1; - asm volatile("# beginning __down_write_trylock\n\t" - " mov %[count],%[tmp0]\n\t" - "1:\n\t" - " test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t" - /* was the active mask 0 before? */ - " jnz 2f\n\t" - " mov %[tmp0],%[tmp1]\n\t" - " add %[inc],%[tmp1]\n\t" - LOCK_PREFIX " cmpxchg %[tmp1],%[count]\n\t" - " jnz 1b\n\t" - "2:\n\t" - CC_SET(e) - "# ending __down_write_trylock\n\t" - : [count] "+m" (sem->count), [tmp0] "=&a" (tmp0), - [tmp1] "=&r" (tmp1), CC_OUT(e) (result) - : [inc] "er" (RWSEM_ACTIVE_WRITE_BIAS) - : "memory"); - return result; -} - -/* - * unlock after reading - */ -static inline void __up_read(struct rw_semaphore *sem) -{ - long tmp; - asm volatile("# beginning __up_read\n\t" - LOCK_PREFIX " xadd %[tmp],(%[sem])\n\t" - /* subtracts 1, returns the old value */ - " jns 1f\n\t" - " call call_rwsem_wake\n" /* expects old value in %edx */ - "1:\n" - "# ending __up_read\n" - : "+m" (sem->count), [tmp] "=d" (tmp) - : [sem] "a" (sem), "[tmp]" (-RWSEM_ACTIVE_READ_BIAS) - : "memory", "cc"); -} - -/* - * unlock after writing - */ -static inline void __up_write(struct rw_semaphore *sem) -{ - long tmp; - asm volatile("# beginning __up_write\n\t" - LOCK_PREFIX " xadd %[tmp],(%[sem])\n\t" - /* subtracts 0xffff0001, returns the old value */ - " jns 1f\n\t" - " call call_rwsem_wake\n" /* expects old value in %edx */ - "1:\n\t" - "# ending __up_write\n" - : "+m" (sem->count), [tmp] "=d" (tmp) - : [sem] "a" (sem), "[tmp]" (-RWSEM_ACTIVE_WRITE_BIAS) - : "memory", "cc"); -} - -/* - * downgrade write lock to read lock - */ -static inline void __downgrade_write(struct rw_semaphore *sem) -{ - asm volatile("# beginning __downgrade_write\n\t" - LOCK_PREFIX _ASM_ADD "%[inc],(%[sem])\n\t" - /* - * transitions 0xZZZZ0001 -> 0xYYYY0001 (i386) - * 0xZZZZZZZZ00000001 -> 0xYYYYYYYY00000001 (x86_64) - */ - " jns 1f\n\t" - " call call_rwsem_downgrade_wake\n" - "1:\n\t" - "# ending __downgrade_write\n" - : "+m" (sem->count) - : [sem] "a" (sem), [inc] "er" (-RWSEM_WAITING_BIAS) - : "memory", "cc"); -} - -#endif /* __KERNEL__ */ -#endif /* _ASM_X86_RWSEM_H */ diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile index 3cb3af51ec89..5246db42de45 100644 --- a/arch/x86/lib/Makefile +++ b/arch/x86/lib/Makefile @@ -35,7 +35,6 @@ obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o lib-y := delay.o misc.o cmdline.o cpu.o lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o lib-y += memcpy_$(BITS).o -lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o insn-eval.o lib-$(CONFIG_RANDOMIZE_BASE) += kaslr.o lib-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o diff --git a/arch/x86/lib/rwsem.S b/arch/x86/lib/rwsem.S deleted file mode 100644 index dc2ab6ea6768..000000000000 --- a/arch/x86/lib/rwsem.S +++ /dev/null @@ -1,156 +0,0 @@ -/* - * x86 semaphore implementation. - * - * (C) Copyright 1999 Linus Torvalds - * - * Portions Copyright 1999 Red Hat, Inc. - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public License - * as published by the Free Software Foundation; either version - * 2 of the License, or (at your option) any later version. - * - * rw semaphores implemented November 1999 by Benjamin LaHaise <bcrl@kvack.org> - */ - -#include <linux/linkage.h> -#include <asm/alternative-asm.h> -#include <asm/frame.h> - -#define __ASM_HALF_REG(reg) __ASM_SEL(reg, e##reg) -#define __ASM_HALF_SIZE(inst) __ASM_SEL(inst##w, inst##l) - -#ifdef CONFIG_X86_32 - -/* - * The semaphore operations have a special calling sequence that - * allow us to do a simpler in-line version of them. These routines - * need to convert that sequence back into the C sequence when - * there is contention on the semaphore. - * - * %eax contains the semaphore pointer on entry. Save the C-clobbered - * registers (%eax, %edx and %ecx) except %eax which is either a return - * value or just gets clobbered. Same is true for %edx so make sure GCC - * reloads it after the slow path, by making it hold a temporary, for - * example see ____down_write(). - */ - -#define save_common_regs \ - pushl %ecx - -#define restore_common_regs \ - popl %ecx - - /* Avoid uglifying the argument copying x86-64 needs to do. */ - .macro movq src, dst - .endm - -#else - -/* - * x86-64 rwsem wrappers - * - * This interfaces the inline asm code to the slow-path - * C routines. We need to save the call-clobbered regs - * that the asm does not mark as clobbered, and move the - * argument from %rax to %rdi. - * - * NOTE! We don't need to save %rax, because the functions - * will always return the semaphore pointer in %rax (which - * is also the input argument to these helpers) - * - * The following can clobber %rdx because the asm clobbers it: - * call_rwsem_down_write_failed - * call_rwsem_wake - * but %rdi, %rsi, %rcx, %r8-r11 always need saving. - */ - -#define save_common_regs \ - pushq %rdi; \ - pushq %rsi; \ - pushq %rcx; \ - pushq %r8; \ - pushq %r9; \ - pushq %r10; \ - pushq %r11 - -#define restore_common_regs \ - popq %r11; \ - popq %r10; \ - popq %r9; \ - popq %r8; \ - popq %rcx; \ - popq %rsi; \ - popq %rdi - -#endif - -/* Fix up special calling conventions */ -ENTRY(call_rwsem_down_read_failed) - FRAME_BEGIN - save_common_regs - __ASM_SIZE(push,) %__ASM_REG(dx) - movq %rax,%rdi - call rwsem_down_read_failed - __ASM_SIZE(pop,) %__ASM_REG(dx) - restore_common_regs - FRAME_END - ret -ENDPROC(call_rwsem_down_read_failed) - -ENTRY(call_rwsem_down_read_failed_killable) - FRAME_BEGIN - save_common_regs - __ASM_SIZE(push,) %__ASM_REG(dx) - movq %rax,%rdi - call rwsem_down_read_failed_killable - __ASM_SIZE(pop,) %__ASM_REG(dx) - restore_common_regs - FRAME_END - ret -ENDPROC(call_rwsem_down_read_failed_killable) - -ENTRY(call_rwsem_down_write_failed) - FRAME_BEGIN - save_common_regs - movq %rax,%rdi - call rwsem_down_write_failed - restore_common_regs - FRAME_END - ret -ENDPROC(call_rwsem_down_write_failed) - -ENTRY(call_rwsem_down_write_failed_killable) - FRAME_BEGIN - save_common_regs - movq %rax,%rdi - call rwsem_down_write_failed_killable - restore_common_regs - FRAME_END - ret -ENDPROC(call_rwsem_down_write_failed_killable) - -ENTRY(call_rwsem_wake) - FRAME_BEGIN - /* do nothing if still outstanding active readers */ - __ASM_HALF_SIZE(dec) %__ASM_HALF_REG(dx) - jnz 1f - save_common_regs - movq %rax,%rdi - call rwsem_wake - restore_common_regs -1: FRAME_END - ret -ENDPROC(call_rwsem_wake) - -ENTRY(call_rwsem_downgrade_wake) - FRAME_BEGIN - save_common_regs - __ASM_SIZE(push,) %__ASM_REG(dx) - movq %rax,%rdi - call rwsem_downgrade_wake - __ASM_SIZE(pop,) %__ASM_REG(dx) - restore_common_regs - FRAME_END - ret -ENDPROC(call_rwsem_downgrade_wake) diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig index a9e80e44178c..a8985e1f7432 100644 --- a/arch/x86/um/Kconfig +++ b/arch/x86/um/Kconfig @@ -32,12 +32,6 @@ config ARCH_DEFCONFIG default "arch/um/configs/i386_defconfig" if X86_32 default "arch/um/configs/x86_64_defconfig" if X86_64 -config RWSEM_XCHGADD_ALGORITHM - def_bool 64BIT - -config RWSEM_GENERIC_SPINLOCK - def_bool !RWSEM_XCHGADD_ALGORITHM - config 3_LEVEL_PGTABLES bool "Three-level pagetables" if !64BIT default 64BIT diff --git a/arch/x86/um/Makefile b/arch/x86/um/Makefile index 2d686ae54681..33c51c064c77 100644 --- a/arch/x86/um/Makefile +++ b/arch/x86/um/Makefile @@ -21,14 +21,12 @@ obj-y += checksum_32.o syscalls_32.o obj-$(CONFIG_ELF_CORE) += elfcore.o subarch-y = ../lib/string_32.o ../lib/atomic64_32.o ../lib/atomic64_cx8_32.o -subarch-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += ../lib/rwsem.o else obj-y += syscalls_64.o vdso/ -subarch-y = ../lib/csum-partial_64.o ../lib/memcpy_64.o ../entry/thunk_64.o \ - ../lib/rwsem.o +subarch-y = ../lib/csum-partial_64.o ../lib/memcpy_64.o ../entry/thunk_64.o endif diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig index 4b9aafe766c5..35c8d91e6106 100644 --- a/arch/xtensa/Kconfig +++ b/arch/xtensa/Kconfig @@ -46,9 +46,6 @@ config XTENSA with reasonable minimum requirements. The Xtensa Linux project has a home page at <http://www.linux-xtensa.org/>. -config RWSEM_XCHGADD_ALGORITHM - def_bool y - config GENERIC_HWEIGHT def_bool y diff --git a/arch/xtensa/include/asm/Kbuild b/arch/xtensa/include/asm/Kbuild index 3843198e03d4..4148090cafb0 100644 --- a/arch/xtensa/include/asm/Kbuild +++ b/arch/xtensa/include/asm/Kbuild @@ -25,7 +25,6 @@ generic-y += percpu.h generic-y += preempt.h generic-y += qrwlock.h generic-y += qspinlock.h -generic-y += rwsem.h generic-y += sections.h generic-y += socket.h generic-y += topology.h diff --git a/include/asm-generic/rwsem.h b/include/asm-generic/rwsem.h deleted file mode 100644 index 93e67a055a4d..000000000000 --- a/include/asm-generic/rwsem.h +++ /dev/null @@ -1,140 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -#ifndef _ASM_GENERIC_RWSEM_H -#define _ASM_GENERIC_RWSEM_H - -#ifndef _LINUX_RWSEM_H -#error "Please don't include <asm/rwsem.h> directly, use <linux/rwsem.h> instead." -#endif - -#ifdef __KERNEL__ - -/* - * R/W semaphores originally for PPC using the stuff in lib/rwsem.c. - * Adapted largely from include/asm-i386/rwsem.h - * by Paul Mackerras <paulus@samba.org>. - */ - -/* - * the semaphore definition - */ -#ifdef CONFIG_64BIT -# define RWSEM_ACTIVE_MASK 0xffffffffL -#else -# define RWSEM_ACTIVE_MASK 0x0000ffffL -#endif - -#define RWSEM_UNLOCKED_VALUE 0x00000000L -#define RWSEM_ACTIVE_BIAS 0x00000001L -#define RWSEM_WAITING_BIAS (-RWSEM_ACTIVE_MASK-1) -#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS -#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) - -/* - * lock for reading - */ -static inline void __down_read(struct rw_semaphore *sem) -{ - if (unlikely(atomic_long_inc_return_acquire(&sem->count) <= 0)) - rwsem_down_read_failed(sem); -} - -static inline int __down_read_killable(struct rw_semaphore *sem) -{ - if (unlikely(atomic_long_inc_return_acquire(&sem->count) <= 0)) { - if (IS_ERR(rwsem_down_read_failed_killable(sem))) - return -EINTR; - } - - return 0; -} - -static inline int __down_read_trylock(struct rw_semaphore *sem) -{ - long tmp; - - while ((tmp = atomic_long_read(&sem->count)) >= 0) { - if (tmp == atomic_long_cmpxchg_acquire(&sem->count, tmp, - tmp + RWSEM_ACTIVE_READ_BIAS)) { - return 1; - } - } - return 0; -} - -/* - * lock for writing - */ -static inline void __down_write(struct rw_semaphore *sem) -{ - long tmp; - - tmp = atomic_long_add_return_acquire(RWSEM_ACTIVE_WRITE_BIAS, - &sem->count); - if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS)) - rwsem_down_write_failed(sem); -} - -static inline int __down_write_killable(struct rw_semaphore *sem) -{ - long tmp; - - tmp = atomic_long_add_return_acquire(RWSEM_ACTIVE_WRITE_BIAS, - &sem->count); - if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS)) - if (IS_ERR(rwsem_down_write_failed_killable(sem))) - return -EINTR; - return 0; -} - -static inline int __down_write_trylock(struct rw_semaphore *sem) -{ - long tmp; - - tmp = atomic_long_cmpxchg_acquire(&sem->count, RWSEM_UNLOCKED_VALUE, - RWSEM_ACTIVE_WRITE_BIAS); - return tmp == RWSEM_UNLOCKED_VALUE; -} - -/* - * unlock after reading - */ -static inline void __up_read(struct rw_semaphore *sem) -{ - long tmp; - - tmp = atomic_long_dec_return_release(&sem->count); - if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)) - rwsem_wake(sem); -} - -/* - * unlock after writing - */ -static inline void __up_write(struct rw_semaphore *sem) -{ - if (unlikely(atomic_long_sub_return_release(RWSEM_ACTIVE_WRITE_BIAS, - &sem->count) < 0)) - rwsem_wake(sem); -} - -/* - * downgrade write lock to read lock - */ -static inline void __downgrade_write(struct rw_semaphore *sem) -{ - long tmp; - - /* - * When downgrading from exclusive to shared ownership, - * anything inside the write-locked region cannot leak - * into the read side. In contrast, anything in the - * read-locked region is ok to be re-ordered into the - * write side. As such, rely on RELEASE semantics. - */ - tmp = atomic_long_add_return_release(-RWSEM_WAITING_BIAS, &sem->count); - if (tmp < 0) - rwsem_downgrade_wake(sem); -} - -#endif /* __KERNEL__ */ -#endif /* _ASM_GENERIC_RWSEM_H */ diff --git a/include/linux/jump_label_ratelimit.h b/include/linux/jump_label_ratelimit.h index a49f2b45b3f0..42710d5949ba 100644 --- a/include/linux/jump_label_ratelimit.h +++ b/include/linux/jump_label_ratelimit.h @@ -12,21 +12,79 @@ struct static_key_deferred { struct delayed_work work; }; -extern void static_key_slow_dec_deferred(struct static_key_deferred *key); -extern void static_key_deferred_flush(struct static_key_deferred *key); +struct static_key_true_deferred { + struct static_key_true key; + unsigned long timeout; + struct delayed_work work; +}; + +struct static_key_false_deferred { + struct static_key_false key; + unsigned long timeout; + struct delayed_work work; +}; + +#define static_key_slow_dec_deferred(x) \ + __static_key_slow_dec_deferred(&(x)->key, &(x)->work, (x)->timeout) +#define static_branch_slow_dec_deferred(x) \ + __static_key_slow_dec_deferred(&(x)->key.key, &(x)->work, (x)->timeout) + +#define static_key_deferred_flush(x) \ + __static_key_deferred_flush((x), &(x)->work) + +extern void +__static_key_slow_dec_deferred(struct static_key *key, + struct delayed_work *work, + unsigned long timeout); +extern void __static_key_deferred_flush(void *key, struct delayed_work *work); extern void jump_label_rate_limit(struct static_key_deferred *key, unsigned long rl); +extern void jump_label_update_timeout(struct work_struct *work); + +#define DEFINE_STATIC_KEY_DEFERRED_TRUE(name, rl) \ + struct static_key_true_deferred name = { \ + .key = { STATIC_KEY_INIT_TRUE }, \ + .timeout = (rl), \ + .work = __DELAYED_WORK_INITIALIZER((name).work, \ + jump_label_update_timeout, \ + 0), \ + } + +#define DEFINE_STATIC_KEY_DEFERRED_FALSE(name, rl) \ + struct static_key_false_deferred name = { \ + .key = { STATIC_KEY_INIT_FALSE }, \ + .timeout = (rl), \ + .work = __DELAYED_WORK_INITIALIZER((name).work, \ + jump_label_update_timeout, \ + 0), \ + } + +#define static_branch_deferred_inc(x) static_branch_inc(&(x)->key) + #else /* !CONFIG_JUMP_LABEL */ struct static_key_deferred { struct static_key key; }; +struct static_key_true_deferred { + struct static_key_true key; +}; +struct static_key_false_deferred { + struct static_key_false key; +}; +#define DEFINE_STATIC_KEY_DEFERRED_TRUE(name, rl) \ + struct static_key_true_deferred name = { STATIC_KEY_TRUE_INIT } +#define DEFINE_STATIC_KEY_DEFERRED_FALSE(name, rl) \ + struct static_key_false_deferred name = { STATIC_KEY_FALSE_INIT } + +#define static_branch_slow_dec_deferred(x) static_branch_dec(&(x)->key) + static inline void static_key_slow_dec_deferred(struct static_key_deferred *key) { STATIC_KEY_CHECK_USE(key); static_key_slow_dec(&key->key); } -static inline void static_key_deferred_flush(struct static_key_deferred *key) +static inline void static_key_deferred_flush(void *key) { STATIC_KEY_CHECK_USE(key); } diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 6f165d625320..6e2377e6c1d6 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -476,7 +476,7 @@ struct pin_cookie { }; #define NIL_COOKIE (struct pin_cookie){ } -#define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; }) +#define lockdep_pin_lock(l) ({ struct pin_cookie cookie = { }; cookie; }) #define lockdep_repin_lock(l, c) do { (void)(l); (void)(c); } while (0) #define lockdep_unpin_lock(l, c) do { (void)(l); (void)(c); } while (0) diff --git a/include/linux/rwsem-spinlock.h b/include/linux/rwsem-spinlock.h deleted file mode 100644 index e47568363e5e..000000000000 --- a/include/linux/rwsem-spinlock.h +++ /dev/null @@ -1,47 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -/* rwsem-spinlock.h: fallback C implementation - * - * Copyright (c) 2001 David Howells (dhowells@redhat.com). - * - Derived partially from ideas by Andrea Arcangeli <andrea@suse.de> - * - Derived also from comments by Linus - */ - -#ifndef _LINUX_RWSEM_SPINLOCK_H -#define _LINUX_RWSEM_SPINLOCK_H - -#ifndef _LINUX_RWSEM_H -#error "please don't include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead" -#endif - -#ifdef __KERNEL__ -/* - * the rw-semaphore definition - * - if count is 0 then there are no active readers or writers - * - if count is +ve then that is the number of active readers - * - if count is -1 then there is one active writer - * - if wait_list is not empty, then there are processes waiting for the semaphore - */ -struct rw_semaphore { - __s32 count; - raw_spinlock_t wait_lock; - struct list_head wait_list; -#ifdef CONFIG_DEBUG_LOCK_ALLOC - struct lockdep_map dep_map; -#endif -}; - -#define RWSEM_UNLOCKED_VALUE 0x00000000 - -extern void __down_read(struct rw_semaphore *sem); -extern int __must_check __down_read_killable(struct rw_semaphore *sem); -extern int __down_read_trylock(struct rw_semaphore *sem); -extern void __down_write(struct rw_semaphore *sem); -extern int __must_check __down_write_killable(struct rw_semaphore *sem); -extern int __down_write_trylock(struct rw_semaphore *sem); -extern void __up_read(struct rw_semaphore *sem); -extern void __up_write(struct rw_semaphore *sem); -extern void __downgrade_write(struct rw_semaphore *sem); -extern int rwsem_is_locked(struct rw_semaphore *sem); - -#endif /* __KERNEL__ */ -#endif /* _LINUX_RWSEM_SPINLOCK_H */ diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index 67dbb57508b1..2ea18a3def04 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -20,25 +20,30 @@ #include <linux/osq_lock.h> #endif -struct rw_semaphore; - -#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK -#include <linux/rwsem-spinlock.h> /* use a generic implementation */ -#define __RWSEM_INIT_COUNT(name) .count = RWSEM_UNLOCKED_VALUE -#else -/* All arch specific implementations share the same struct */ +/* + * For an uncontended rwsem, count and owner are the only fields a task + * needs to touch when acquiring the rwsem. So they are put next to each + * other to increase the chance that they will share the same cacheline. + * + * In a contended rwsem, the owner is likely the most frequently accessed + * field in the structure as the optimistic waiter that holds the osq lock + * will spin on owner. For an embedded rwsem, other hot fields in the + * containing structure should be moved further away from the rwsem to + * reduce the chance that they will share the same cacheline causing + * cacheline bouncing problem. + */ struct rw_semaphore { atomic_long_t count; - struct list_head wait_list; - raw_spinlock_t wait_lock; #ifdef CONFIG_RWSEM_SPIN_ON_OWNER - struct optimistic_spin_queue osq; /* spinner MCS lock */ /* * Write owner. Used as a speculative check to see * if the owner is running on the cpu. */ struct task_struct *owner; + struct optimistic_spin_queue osq; /* spinner MCS lock */ #endif + raw_spinlock_t wait_lock; + struct list_head wait_list; #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map dep_map; #endif @@ -50,24 +55,14 @@ struct rw_semaphore { */ #define RWSEM_OWNER_UNKNOWN ((struct task_struct *)-2L) -extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem); -extern struct rw_semaphore *rwsem_down_read_failed_killable(struct rw_semaphore *sem); -extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem); -extern struct rw_semaphore *rwsem_down_write_failed_killable(struct rw_semaphore *sem); -extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *); -extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem); - -/* Include the arch specific part */ -#include <asm/rwsem.h> - /* In all implementations count != 0 means locked */ static inline int rwsem_is_locked(struct rw_semaphore *sem) { return atomic_long_read(&sem->count) != 0; } +#define RWSEM_UNLOCKED_VALUE 0L #define __RWSEM_INIT_COUNT(name) .count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE) -#endif /* Common initializer macros and functions */ diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks index fbba478ae522..e335953fa704 100644 --- a/kernel/Kconfig.locks +++ b/kernel/Kconfig.locks @@ -229,7 +229,7 @@ config MUTEX_SPIN_ON_OWNER config RWSEM_SPIN_ON_OWNER def_bool y - depends on SMP && RWSEM_XCHGADD_ALGORITHM && ARCH_SUPPORTS_ATOMIC_RMW + depends on SMP && ARCH_SUPPORTS_ATOMIC_RMW config LOCK_SPIN_ON_OWNER def_bool y diff --git a/kernel/jump_label.c b/kernel/jump_label.c index bad96b476eb6..de6efdecc70d 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -202,11 +202,13 @@ void static_key_disable(struct static_key *key) } EXPORT_SYMBOL_GPL(static_key_disable); -static void __static_key_slow_dec_cpuslocked(struct static_key *key, - unsigned long rate_limit, - struct delayed_work *work) +static bool static_key_slow_try_dec(struct static_key *key) { - lockdep_assert_cpus_held(); + int val; + + val = atomic_fetch_add_unless(&key->enabled, -1, 1); + if (val == 1) + return false; /* * The negative count check is valid even when a negative @@ -215,63 +217,70 @@ static void __static_key_slow_dec_cpuslocked(struct static_key *key, * returns is unbalanced, because all other static_key_slow_inc() * instances block while the update is in progress. */ - if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) { - WARN(atomic_read(&key->enabled) < 0, - "jump label: negative count!\n"); + WARN(val < 0, "jump label: negative count!\n"); + return true; +} + +static void __static_key_slow_dec_cpuslocked(struct static_key *key) +{ + lockdep_assert_cpus_held(); + + if (static_key_slow_try_dec(key)) return; - } - if (rate_limit) { - atomic_inc(&key->enabled); - schedule_delayed_work(work, rate_limit); - } else { + jump_label_lock(); + if (atomic_dec_and_test(&key->enabled)) jump_label_update(key); - } jump_label_unlock(); } -static void __static_key_slow_dec(struct static_key *key, - unsigned long rate_limit, - struct delayed_work *work) +static void __static_key_slow_dec(struct static_key *key) { cpus_read_lock(); - __static_key_slow_dec_cpuslocked(key, rate_limit, work); + __static_key_slow_dec_cpuslocked(key); cpus_read_unlock(); } -static void jump_label_update_timeout(struct work_struct *work) +void jump_label_update_timeout(struct work_struct *work) { struct static_key_deferred *key = container_of(work, struct static_key_deferred, work.work); - __static_key_slow_dec(&key->key, 0, NULL); + __static_key_slow_dec(&key->key); } +EXPORT_SYMBOL_GPL(jump_label_update_timeout); void static_key_slow_dec(struct static_key *key) { STATIC_KEY_CHECK_USE(key); - __static_key_slow_dec(key, 0, NULL); + __static_key_slow_dec(key); } EXPORT_SYMBOL_GPL(static_key_slow_dec); void static_key_slow_dec_cpuslocked(struct static_key *key) { STATIC_KEY_CHECK_USE(key); - __static_key_slow_dec_cpuslocked(key, 0, NULL); + __static_key_slow_dec_cpuslocked(key); } -void static_key_slow_dec_deferred(struct static_key_deferred *key) +void __static_key_slow_dec_deferred(struct static_key *key, + struct delayed_work *work, + unsigned long timeout) { STATIC_KEY_CHECK_USE(key); - __static_key_slow_dec(&key->key, key->timeout, &key->work); + + if (static_key_slow_try_dec(key)) + return; + + schedule_delayed_work(work, timeout); } -EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred); +EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred); -void static_key_deferred_flush(struct static_key_deferred *key) +void __static_key_deferred_flush(void *key, struct delayed_work *work) { STATIC_KEY_CHECK_USE(key); - flush_delayed_work(&key->work); + flush_delayed_work(work); } -EXPORT_SYMBOL_GPL(static_key_deferred_flush); +EXPORT_SYMBOL_GPL(__static_key_deferred_flush); void jump_label_rate_limit(struct static_key_deferred *key, unsigned long rl) diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile index 392c7f23af76..6fe2f333aecb 100644 --- a/kernel/locking/Makefile +++ b/kernel/locking/Makefile @@ -3,7 +3,7 @@ # and is generally not a function of system call inputs. KCOV_INSTRUMENT := n -obj-y += mutex.o semaphore.o rwsem.o percpu-rwsem.o +obj-y += mutex.o semaphore.o rwsem.o percpu-rwsem.o rwsem-xadd.o ifdef CONFIG_FUNCTION_TRACER CFLAGS_REMOVE_lockdep.o = $(CC_FLAGS_FTRACE) @@ -25,8 +25,7 @@ obj-$(CONFIG_RT_MUTEXES) += rtmutex.o obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o -obj-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o -obj-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem-xadd.o obj-$(CONFIG_QUEUED_RWLOCKS) += qrwlock.o obj-$(CONFIG_LOCK_TORTURE_TEST) += locktorture.o obj-$(CONFIG_WW_MUTEX_SELFTEST) += test-ww_mutex.o +obj-$(CONFIG_LOCK_EVENT_COUNTS) += lock_events.o diff --git a/kernel/locking/lock_events.c b/kernel/locking/lock_events.c new file mode 100644 index 000000000000..fa2c2f951c6b --- /dev/null +++ b/kernel/locking/lock_events.c @@ -0,0 +1,179 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * Authors: Waiman Long <waiman.long@hpe.com> + */ + +/* + * Collect locking event counts + */ +#include <linux/debugfs.h> +#include <linux/sched.h> +#include <linux/sched/clock.h> +#include <linux/fs.h> + +#include "lock_events.h" + +#undef LOCK_EVENT +#define LOCK_EVENT(name) [LOCKEVENT_ ## name] = #name, + +#define LOCK_EVENTS_DIR "lock_event_counts" + +/* + * When CONFIG_LOCK_EVENT_COUNTS is enabled, event counts of different + * types of locks will be reported under the <debugfs>/lock_event_counts/ + * directory. See lock_events_list.h for the list of available locking + * events. + * + * Writing to the special ".reset_counts" file will reset all the above + * locking event counts. This is a very slow operation and so should not + * be done frequently. + * + * These event counts are implemented as per-cpu variables which are + * summed and computed whenever the corresponding debugfs files are read. This + * minimizes added overhead making the counts usable even in a production + * environment. + */ +static const char * const lockevent_names[lockevent_num + 1] = { + +#include "lock_events_list.h" + + [LOCKEVENT_reset_cnts] = ".reset_counts", +}; + +/* + * Per-cpu counts + */ +DEFINE_PER_CPU(unsigned long, lockevents[lockevent_num]); + +/* + * The lockevent_read() function can be overridden. + */ +ssize_t __weak lockevent_read(struct file *file, char __user *user_buf, + size_t count, loff_t *ppos) +{ + char buf[64]; + int cpu, id, len; + u64 sum = 0; + + /* + * Get the counter ID stored in file->f_inode->i_private + */ + id = (long)file_inode(file)->i_private; + + if (id >= lockevent_num) + return -EBADF; + + for_each_possible_cpu(cpu) + sum += per_cpu(lockevents[id], cpu); + len = snprintf(buf, sizeof(buf) - 1, "%llu\n", sum); + + return simple_read_from_buffer(user_buf, count, ppos, buf, len); +} + +/* + * Function to handle write request + * + * When idx = reset_cnts, reset all the counts. + */ +static ssize_t lockevent_write(struct file *file, const char __user *user_buf, + size_t count, loff_t *ppos) +{ + int cpu; + + /* + * Get the counter ID stored in file->f_inode->i_private + */ + if ((long)file_inode(file)->i_private != LOCKEVENT_reset_cnts) + return count; + + for_each_possible_cpu(cpu) { + int i; + unsigned long *ptr = per_cpu_ptr(lockevents, cpu); + + for (i = 0 ; i < lockevent_num; i++) + WRITE_ONCE(ptr[i], 0); + } + return count; +} + +/* + * Debugfs data structures + */ +static const struct file_operations fops_lockevent = { + .read = lockevent_read, + .write = lockevent_write, + .llseek = default_llseek, +}; + +#ifdef CONFIG_PARAVIRT_SPINLOCKS +#include <asm/paravirt.h> + +static bool __init skip_lockevent(const char *name) +{ + static int pv_on __initdata = -1; + + if (pv_on < 0) + pv_on = !pv_is_native_spin_unlock(); + /* + * Skip PV qspinlock events on bare metal. + */ + if (!pv_on && !memcmp(name, "pv_", 3)) + return true; + return false; +} +#else +static inline bool skip_lockevent(const char *name) +{ + return false; +} +#endif + +/* + * Initialize debugfs for the locking event counts. + */ +static int __init init_lockevent_counts(void) +{ + struct dentry *d_counts = debugfs_create_dir(LOCK_EVENTS_DIR, NULL); + int i; + + if (!d_counts) + goto out; + + /* + * Create the debugfs files + * + * As reading from and writing to the stat files can be slow, only + * root is allowed to do the read/write to limit impact to system + * performance. + */ + for (i = 0; i < lockevent_num; i++) { + if (skip_lockevent(lockevent_names[i])) + continue; + if (!debugfs_create_file(lockevent_names[i], 0400, d_counts, + (void *)(long)i, &fops_lockevent)) + goto fail_undo; + } + + if (!debugfs_create_file(lockevent_names[LOCKEVENT_reset_cnts], 0200, + d_counts, (void *)(long)LOCKEVENT_reset_cnts, + &fops_lockevent)) + goto fail_undo; + + return 0; +fail_undo: + debugfs_remove_recursive(d_counts); +out: + pr_warn("Could not create '%s' debugfs entries\n", LOCK_EVENTS_DIR); + return -ENOMEM; +} +fs_initcall(init_lockevent_counts); diff --git a/kernel/locking/lock_events.h b/kernel/locking/lock_events.h new file mode 100644 index 000000000000..feb1acc54611 --- /dev/null +++ b/kernel/locking/lock_events.h @@ -0,0 +1,59 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * Authors: Waiman Long <longman@redhat.com> + */ + +#ifndef __LOCKING_LOCK_EVENTS_H +#define __LOCKING_LOCK_EVENTS_H + +enum lock_events { + +#include "lock_events_list.h" + + lockevent_num, /* Total number of lock event counts */ + LOCKEVENT_reset_cnts = lockevent_num, +}; + +#ifdef CONFIG_LOCK_EVENT_COUNTS +/* + * Per-cpu counters + */ +DECLARE_PER_CPU(unsigned long, lockevents[lockevent_num]); + +/* + * Increment the PV qspinlock statistical counters + */ +static inline void __lockevent_inc(enum lock_events event, bool cond) +{ + if (cond) + __this_cpu_inc(lockevents[event]); +} + +#define lockevent_inc(ev) __lockevent_inc(LOCKEVENT_ ##ev, true) +#define lockevent_cond_inc(ev, c) __lockevent_inc(LOCKEVENT_ ##ev, c) + +static inline void __lockevent_add(enum lock_events event, int inc) +{ + __this_cpu_add(lockevents[event], inc); +} + +#define lockevent_add(ev, c) __lockevent_add(LOCKEVENT_ ##ev, c) + +#else /* CONFIG_LOCK_EVENT_COUNTS */ + +#define lockevent_inc(ev) +#define lockevent_add(ev, c) +#define lockevent_cond_inc(ev, c) + +#endif /* CONFIG_LOCK_EVENT_COUNTS */ +#endif /* __LOCKING_LOCK_EVENTS_H */ diff --git a/kernel/locking/lock_events_list.h b/kernel/locking/lock_events_list.h new file mode 100644 index 000000000000..ad7668cfc9da --- /dev/null +++ b/kernel/locking/lock_events_list.h @@ -0,0 +1,67 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * Authors: Waiman Long <longman@redhat.com> + */ + +#ifndef LOCK_EVENT +#define LOCK_EVENT(name) LOCKEVENT_ ## name, +#endif + +#ifdef CONFIG_QUEUED_SPINLOCKS +#ifdef CONFIG_PARAVIRT_SPINLOCKS +/* + * Locking events for PV qspinlock. + */ +LOCK_EVENT(pv_hash_hops) /* Average # of hops per hashing operation */ +LOCK_EVENT(pv_kick_unlock) /* # of vCPU kicks issued at unlock time */ +LOCK_EVENT(pv_kick_wake) /* # of vCPU kicks for pv_latency_wake */ +LOCK_EVENT(pv_latency_kick) /* Average latency (ns) of vCPU kick */ +LOCK_EVENT(pv_latency_wake) /* Average latency (ns) of kick-to-wakeup */ +LOCK_EVENT(pv_lock_stealing) /* # of lock stealing operations */ +LOCK_EVENT(pv_spurious_wakeup) /* # of spurious wakeups in non-head vCPUs */ +LOCK_EVENT(pv_wait_again) /* # of wait's after queue head vCPU kick */ +LOCK_EVENT(pv_wait_early) /* # of early vCPU wait's */ +LOCK_EVENT(pv_wait_head) /* # of vCPU wait's at the queue head */ +LOCK_EVENT(pv_wait_node) /* # of vCPU wait's at non-head queue node */ +#endif /* CONFIG_PARAVIRT_SPINLOCKS */ + +/* + * Locking events for qspinlock + * + * Subtracting lock_use_node[234] from lock_slowpath will give you + * lock_use_node1. + */ +LOCK_EVENT(lock_pending) /* # of locking ops via pending code */ +LOCK_EVENT(lock_slowpath) /* # of locking ops via MCS lock queue */ +LOCK_EVENT(lock_use_node2) /* # of locking ops that use 2nd percpu node */ +LOCK_EVENT(lock_use_node3) /* # of locking ops that use 3rd percpu node */ +LOCK_EVENT(lock_use_node4) /* # of locking ops that use 4th percpu node */ +LOCK_EVENT(lock_no_node) /* # of locking ops w/o using percpu node */ +#endif /* CONFIG_QUEUED_SPINLOCKS */ + +/* + * Locking events for rwsem + */ +LOCK_EVENT(rwsem_sleep_reader) /* # of reader sleeps */ +LOCK_EVENT(rwsem_sleep_writer) /* # of writer sleeps */ +LOCK_EVENT(rwsem_wake_reader) /* # of reader wakeups */ +LOCK_EVENT(rwsem_wake_writer) /* # of writer wakeups */ +LOCK_EVENT(rwsem_opt_wlock) /* # of write locks opt-spin acquired */ +LOCK_EVENT(rwsem_opt_fail) /* # of failed opt-spinnings */ +LOCK_EVENT(rwsem_rlock) /* # of read locks acquired */ +LOCK_EVENT(rwsem_rlock_fast) /* # of fast read locks acquired */ +LOCK_EVENT(rwsem_rlock_fail) /* # of failed read lock acquisitions */ +LOCK_EVENT(rwsem_rtrylock) /* # of read trylock calls */ +LOCK_EVENT(rwsem_wlock) /* # of write locks acquired */ +LOCK_EVENT(rwsem_wlock_fail) /* # of failed write lock acquisitions */ +LOCK_EVENT(rwsem_wtrylock) /* # of write trylock calls */ diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 91c6b89f04df..27b992fe8cec 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -501,11 +501,11 @@ static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) { char c = '.'; - if (class->usage_mask & lock_flag(bit + 2)) + if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) c = '+'; if (class->usage_mask & lock_flag(bit)) { c = '-'; - if (class->usage_mask & lock_flag(bit + 2)) + if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) c = '?'; } @@ -1666,19 +1666,25 @@ check_redundant(struct lock_list *root, struct lock_class *target, } #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) + +static inline int usage_accumulate(struct lock_list *entry, void *mask) +{ + *(unsigned long *)mask |= entry->class->usage_mask; + + return 0; +} + /* * Forwards and backwards subgraph searching, for the purposes of * proving that two subgraphs can be connected by a new dependency * without creating any illegal irq-safe -> irq-unsafe lock dependency. */ -static inline int usage_match(struct lock_list *entry, void *bit) +static inline int usage_match(struct lock_list *entry, void *mask) { - return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit); + return entry->class->usage_mask & *(unsigned long *)mask; } - - /* * Find a node in the forwards-direction dependency sub-graph starting * at @root->class that matches @bit. @@ -1690,14 +1696,14 @@ static inline int usage_match(struct lock_list *entry, void *bit) * Return <0 on error. */ static int -find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit, +find_usage_forwards(struct lock_list *root, unsigned long usage_mask, struct lock_list **target_entry) { int result; debug_atomic_inc(nr_find_usage_forwards_checks); - result = __bfs_forwards(root, (void *)bit, usage_match, target_entry); + result = __bfs_forwards(root, &usage_mask, usage_match, target_entry); return result; } @@ -1713,14 +1719,14 @@ find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit, * Return <0 on error. */ static int -find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit, +find_usage_backwards(struct lock_list *root, unsigned long usage_mask, struct lock_list **target_entry) { int result; debug_atomic_inc(nr_find_usage_backwards_checks); - result = __bfs_backwards(root, (void *)bit, usage_match, target_entry); + result = __bfs_backwards(root, &usage_mask, usage_match, target_entry); return result; } @@ -1912,39 +1918,6 @@ print_bad_irq_dependency(struct task_struct *curr, return 0; } -static int -check_usage(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next, enum lock_usage_bit bit_backwards, - enum lock_usage_bit bit_forwards, const char *irqclass) -{ - int ret; - struct lock_list this, that; - struct lock_list *uninitialized_var(target_entry); - struct lock_list *uninitialized_var(target_entry1); - - this.parent = NULL; - - this.class = hlock_class(prev); - ret = find_usage_backwards(&this, bit_backwards, &target_entry); - if (ret < 0) - return print_bfs_bug(ret); - if (ret == 1) - return ret; - - that.parent = NULL; - that.class = hlock_class(next); - ret = find_usage_forwards(&that, bit_forwards, &target_entry1); - if (ret < 0) - return print_bfs_bug(ret); - if (ret == 1) - return ret; - - return print_bad_irq_dependency(curr, &this, &that, - target_entry, target_entry1, - prev, next, - bit_backwards, bit_forwards, irqclass); -} - static const char *state_names[] = { #define LOCKDEP_STATE(__STATE) \ __stringify(__STATE), @@ -1961,9 +1934,19 @@ static const char *state_rnames[] = { static inline const char *state_name(enum lock_usage_bit bit) { - return (bit & LOCK_USAGE_READ_MASK) ? state_rnames[bit >> 2] : state_names[bit >> 2]; + if (bit & LOCK_USAGE_READ_MASK) + return state_rnames[bit >> LOCK_USAGE_DIR_MASK]; + else + return state_names[bit >> LOCK_USAGE_DIR_MASK]; } +/* + * The bit number is encoded like: + * + * bit0: 0 exclusive, 1 read lock + * bit1: 0 used in irq, 1 irq enabled + * bit2-n: state + */ static int exclusive_bit(int new_bit) { int state = new_bit & LOCK_USAGE_STATE_MASK; @@ -1975,45 +1958,160 @@ static int exclusive_bit(int new_bit) return state | (dir ^ LOCK_USAGE_DIR_MASK); } +/* + * Observe that when given a bitmask where each bitnr is encoded as above, a + * right shift of the mask transforms the individual bitnrs as -1 and + * conversely, a left shift transforms into +1 for the individual bitnrs. + * + * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can + * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0) + * instead by subtracting the bit number by 2, or shifting the mask right by 2. + * + * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2. + * + * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is + * all bits set) and recompose with bitnr1 flipped. + */ +static unsigned long invert_dir_mask(unsigned long mask) +{ + unsigned long excl = 0; + + /* Invert dir */ + excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK; + excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK; + + return excl; +} + +/* + * As above, we clear bitnr0 (LOCK_*_READ off) with bitmask ops. First, for all + * bits with bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*). + * And then mask out all bitnr0. + */ +static unsigned long exclusive_mask(unsigned long mask) +{ + unsigned long excl = invert_dir_mask(mask); + + /* Strip read */ + excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK; + excl &= ~LOCKF_IRQ_READ; + + return excl; +} + +/* + * Retrieve the _possible_ original mask to which @mask is + * exclusive. Ie: this is the opposite of exclusive_mask(). + * Note that 2 possible original bits can match an exclusive + * bit: one has LOCK_USAGE_READ_MASK set, the other has it + * cleared. So both are returned for each exclusive bit. + */ +static unsigned long original_mask(unsigned long mask) +{ + unsigned long excl = invert_dir_mask(mask); + + /* Include read in existing usages */ + excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK; + + return excl; +} + +/* + * Find the first pair of bit match between an original + * usage mask and an exclusive usage mask. + */ +static int find_exclusive_match(unsigned long mask, + unsigned long excl_mask, + enum lock_usage_bit *bitp, + enum lock_usage_bit *excl_bitp) +{ + int bit, excl; + + for_each_set_bit(bit, &mask, LOCK_USED) { + excl = exclusive_bit(bit); + if (excl_mask & lock_flag(excl)) { + *bitp = bit; + *excl_bitp = excl; + return 0; + } + } + return -1; +} + +/* + * Prove that the new dependency does not connect a hardirq-safe(-read) + * lock with a hardirq-unsafe lock - to achieve this we search + * the backwards-subgraph starting at <prev>, and the + * forwards-subgraph starting at <next>: + */ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next, enum lock_usage_bit bit) + struct held_lock *next) { + unsigned long usage_mask = 0, forward_mask, backward_mask; + enum lock_usage_bit forward_bit = 0, backward_bit = 0; + struct lock_list *uninitialized_var(target_entry1); + struct lock_list *uninitialized_var(target_entry); + struct lock_list this, that; + int ret; + /* - * Prove that the new dependency does not connect a hardirq-safe - * lock with a hardirq-unsafe lock - to achieve this we search - * the backwards-subgraph starting at <prev>, and the - * forwards-subgraph starting at <next>: + * Step 1: gather all hard/soft IRQs usages backward in an + * accumulated usage mask. */ - if (!check_usage(curr, prev, next, bit, - exclusive_bit(bit), state_name(bit))) - return 0; + this.parent = NULL; + this.class = hlock_class(prev); + + ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, NULL); + if (ret < 0) + return print_bfs_bug(ret); - bit++; /* _READ */ + usage_mask &= LOCKF_USED_IN_IRQ_ALL; + if (!usage_mask) + return 1; /* - * Prove that the new dependency does not connect a hardirq-safe-read - * lock with a hardirq-unsafe lock - to achieve this we search - * the backwards-subgraph starting at <prev>, and the - * forwards-subgraph starting at <next>: + * Step 2: find exclusive uses forward that match the previous + * backward accumulated mask. */ - if (!check_usage(curr, prev, next, bit, - exclusive_bit(bit), state_name(bit))) - return 0; + forward_mask = exclusive_mask(usage_mask); - return 1; -} + that.parent = NULL; + that.class = hlock_class(next); -static int -check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next) -{ -#define LOCKDEP_STATE(__STATE) \ - if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \ - return 0; -#include "lockdep_states.h" -#undef LOCKDEP_STATE + ret = find_usage_forwards(&that, forward_mask, &target_entry1); + if (ret < 0) + return print_bfs_bug(ret); + if (ret == 1) + return ret; - return 1; + /* + * Step 3: we found a bad match! Now retrieve a lock from the backward + * list whose usage mask matches the exclusive usage mask from the + * lock found on the forward list. + */ + backward_mask = original_mask(target_entry1->class->usage_mask); + + ret = find_usage_backwards(&this, backward_mask, &target_entry); + if (ret < 0) + return print_bfs_bug(ret); + if (DEBUG_LOCKS_WARN_ON(ret == 1)) + return 1; + + /* + * Step 4: narrow down to a pair of incompatible usage bits + * and report it. + */ + ret = find_exclusive_match(target_entry->class->usage_mask, + target_entry1->class->usage_mask, + &backward_bit, &forward_bit); + if (DEBUG_LOCKS_WARN_ON(ret == -1)) + return 1; + + return print_bad_irq_dependency(curr, &this, &that, + target_entry, target_entry1, + prev, next, + backward_bit, forward_bit, + state_name(backward_bit)); } static void inc_chains(void) @@ -2030,9 +2128,8 @@ static void inc_chains(void) #else -static inline int -check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next) +static inline int check_irq_usage(struct task_struct *curr, + struct held_lock *prev, struct held_lock *next) { return 1; } @@ -2211,7 +2308,7 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, else if (unlikely(ret < 0)) return print_bfs_bug(ret); - if (!check_prev_add_irq(curr, prev, next)) + if (!check_irq_usage(curr, prev, next)) return 0; /* @@ -2773,6 +2870,12 @@ static void check_chain_key(struct task_struct *curr) #endif } +static int mark_lock(struct task_struct *curr, struct held_lock *this, + enum lock_usage_bit new_bit); + +#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) + + static void print_usage_bug_scenario(struct held_lock *lock) { @@ -2842,10 +2945,6 @@ valid_state(struct task_struct *curr, struct held_lock *this, return 1; } -static int mark_lock(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit new_bit); - -#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) /* * print irq inversion bug: @@ -2925,7 +3024,7 @@ check_usage_forwards(struct task_struct *curr, struct held_lock *this, root.parent = NULL; root.class = hlock_class(this); - ret = find_usage_forwards(&root, bit, &target_entry); + ret = find_usage_forwards(&root, lock_flag(bit), &target_entry); if (ret < 0) return print_bfs_bug(ret); if (ret == 1) @@ -2949,7 +3048,7 @@ check_usage_backwards(struct task_struct *curr, struct held_lock *this, root.parent = NULL; root.class = hlock_class(this); - ret = find_usage_backwards(&root, bit, &target_entry); + ret = find_usage_backwards(&root, lock_flag(bit), &target_entry); if (ret < 0) return print_bfs_bug(ret); if (ret == 1) @@ -3004,7 +3103,7 @@ static int (*state_verbose_f[])(struct lock_class *class) = { static inline int state_verbose(enum lock_usage_bit bit, struct lock_class *class) { - return state_verbose_f[bit >> 2](class); + return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class); } typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, @@ -3146,7 +3245,7 @@ void lockdep_hardirqs_on(unsigned long ip) /* * See the fine text that goes along with this variable definition. */ - if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))) + if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled)) return; /* diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h index d4c197425f68..150ec3f0c5b5 100644 --- a/kernel/locking/lockdep_internals.h +++ b/kernel/locking/lockdep_internals.h @@ -42,13 +42,35 @@ enum { __LOCKF(USED) }; -#define LOCKF_ENABLED_IRQ (LOCKF_ENABLED_HARDIRQ | LOCKF_ENABLED_SOFTIRQ) -#define LOCKF_USED_IN_IRQ (LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ) +#define LOCKDEP_STATE(__STATE) LOCKF_ENABLED_##__STATE | +static const unsigned long LOCKF_ENABLED_IRQ = +#include "lockdep_states.h" + 0; +#undef LOCKDEP_STATE + +#define LOCKDEP_STATE(__STATE) LOCKF_USED_IN_##__STATE | +static const unsigned long LOCKF_USED_IN_IRQ = +#include "lockdep_states.h" + 0; +#undef LOCKDEP_STATE + +#define LOCKDEP_STATE(__STATE) LOCKF_ENABLED_##__STATE##_READ | +static const unsigned long LOCKF_ENABLED_IRQ_READ = +#include "lockdep_states.h" + 0; +#undef LOCKDEP_STATE + +#define LOCKDEP_STATE(__STATE) LOCKF_USED_IN_##__STATE##_READ | +static const unsigned long LOCKF_USED_IN_IRQ_READ = +#include "lockdep_states.h" + 0; +#undef LOCKDEP_STATE + +#define LOCKF_ENABLED_IRQ_ALL (LOCKF_ENABLED_IRQ | LOCKF_ENABLED_IRQ_READ) +#define LOCKF_USED_IN_IRQ_ALL (LOCKF_USED_IN_IRQ | LOCKF_USED_IN_IRQ_READ) -#define LOCKF_ENABLED_IRQ_READ \ - (LOCKF_ENABLED_HARDIRQ_READ | LOCKF_ENABLED_SOFTIRQ_READ) -#define LOCKF_USED_IN_IRQ_READ \ - (LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ) +#define LOCKF_IRQ (LOCKF_ENABLED_IRQ | LOCKF_USED_IN_IRQ) +#define LOCKF_IRQ_READ (LOCKF_ENABLED_IRQ_READ | LOCKF_USED_IN_IRQ_READ) /* * CONFIG_LOCKDEP_SMALL is defined for sparc. Sparc requires .text, diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c index 883cf1b92d90..f17dad99eec8 100644 --- a/kernel/locking/percpu-rwsem.c +++ b/kernel/locking/percpu-rwsem.c @@ -7,6 +7,8 @@ #include <linux/sched.h> #include <linux/errno.h> +#include "rwsem.h" + int __percpu_init_rwsem(struct percpu_rw_semaphore *sem, const char *name, struct lock_class_key *rwsem_key) { diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c index 5e9247dc2515..e14b32c69639 100644 --- a/kernel/locking/qspinlock.c +++ b/kernel/locking/qspinlock.c @@ -395,7 +395,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) * 0,1,0 -> 0,0,1 */ clear_pending_set_locked(lock); - qstat_inc(qstat_lock_pending, true); + lockevent_inc(lock_pending); return; /* @@ -403,7 +403,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) * queuing. */ queue: - qstat_inc(qstat_lock_slowpath, true); + lockevent_inc(lock_slowpath); pv_queue: node = this_cpu_ptr(&qnodes[0].mcs); idx = node->count++; @@ -419,7 +419,7 @@ pv_queue: * simple enough. */ if (unlikely(idx >= MAX_NODES)) { - qstat_inc(qstat_lock_no_node, true); + lockevent_inc(lock_no_node); while (!queued_spin_trylock(lock)) cpu_relax(); goto release; @@ -430,7 +430,7 @@ pv_queue: /* * Keep counts of non-zero index values: */ - qstat_inc(qstat_lock_use_node2 + idx - 1, idx); + lockevent_cond_inc(lock_use_node2 + idx - 1, idx); /* * Ensure that we increment the head node->count before initialising diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h index 8f36c27c1794..89bab079e7a4 100644 --- a/kernel/locking/qspinlock_paravirt.h +++ b/kernel/locking/qspinlock_paravirt.h @@ -89,7 +89,7 @@ static inline bool pv_hybrid_queued_unfair_trylock(struct qspinlock *lock) if (!(val & _Q_LOCKED_PENDING_MASK) && (cmpxchg_acquire(&lock->locked, 0, _Q_LOCKED_VAL) == 0)) { - qstat_inc(qstat_pv_lock_stealing, true); + lockevent_inc(pv_lock_stealing); return true; } if (!(val & _Q_TAIL_MASK) || (val & _Q_PENDING_MASK)) @@ -219,7 +219,7 @@ static struct qspinlock **pv_hash(struct qspinlock *lock, struct pv_node *node) hopcnt++; if (!cmpxchg(&he->lock, NULL, lock)) { WRITE_ONCE(he->node, node); - qstat_hop(hopcnt); + lockevent_pv_hop(hopcnt); return &he->lock; } } @@ -320,8 +320,8 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev) smp_store_mb(pn->state, vcpu_halted); if (!READ_ONCE(node->locked)) { - qstat_inc(qstat_pv_wait_node, true); - qstat_inc(qstat_pv_wait_early, wait_early); + lockevent_inc(pv_wait_node); + lockevent_cond_inc(pv_wait_early, wait_early); pv_wait(&pn->state, vcpu_halted); } @@ -339,7 +339,8 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev) * So it is better to spin for a while in the hope that the * MCS lock will be released soon. */ - qstat_inc(qstat_pv_spurious_wakeup, !READ_ONCE(node->locked)); + lockevent_cond_inc(pv_spurious_wakeup, + !READ_ONCE(node->locked)); } /* @@ -416,7 +417,7 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct mcs_spinlock *node) /* * Tracking # of slowpath locking operations */ - qstat_inc(qstat_lock_slowpath, true); + lockevent_inc(lock_slowpath); for (;; waitcnt++) { /* @@ -464,8 +465,8 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct mcs_spinlock *node) } } WRITE_ONCE(pn->state, vcpu_hashed); - qstat_inc(qstat_pv_wait_head, true); - qstat_inc(qstat_pv_wait_again, waitcnt); + lockevent_inc(pv_wait_head); + lockevent_cond_inc(pv_wait_again, waitcnt); pv_wait(&lock->locked, _Q_SLOW_VAL); /* @@ -528,7 +529,7 @@ __pv_queued_spin_unlock_slowpath(struct qspinlock *lock, u8 locked) * vCPU is harmless other than the additional latency in completing * the unlock. */ - qstat_inc(qstat_pv_kick_unlock, true); + lockevent_inc(pv_kick_unlock); pv_kick(node->cpu); } diff --git a/kernel/locking/qspinlock_stat.h b/kernel/locking/qspinlock_stat.h index d73f85388d5c..54152670ff24 100644 --- a/kernel/locking/qspinlock_stat.h +++ b/kernel/locking/qspinlock_stat.h @@ -9,262 +9,105 @@ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * - * Authors: Waiman Long <waiman.long@hpe.com> + * Authors: Waiman Long <longman@redhat.com> */ -/* - * When queued spinlock statistical counters are enabled, the following - * debugfs files will be created for reporting the counter values: - * - * <debugfs>/qlockstat/ - * pv_hash_hops - average # of hops per hashing operation - * pv_kick_unlock - # of vCPU kicks issued at unlock time - * pv_kick_wake - # of vCPU kicks used for computing pv_latency_wake - * pv_latency_kick - average latency (ns) of vCPU kick operation - * pv_latency_wake - average latency (ns) from vCPU kick to wakeup - * pv_lock_stealing - # of lock stealing operations - * pv_spurious_wakeup - # of spurious wakeups in non-head vCPUs - * pv_wait_again - # of wait's after a queue head vCPU kick - * pv_wait_early - # of early vCPU wait's - * pv_wait_head - # of vCPU wait's at the queue head - * pv_wait_node - # of vCPU wait's at a non-head queue node - * lock_pending - # of locking operations via pending code - * lock_slowpath - # of locking operations via MCS lock queue - * lock_use_node2 - # of locking operations that use 2nd per-CPU node - * lock_use_node3 - # of locking operations that use 3rd per-CPU node - * lock_use_node4 - # of locking operations that use 4th per-CPU node - * lock_no_node - # of locking operations without using per-CPU node - * - * Subtracting lock_use_node[234] from lock_slowpath will give you - * lock_use_node1. - * - * Writing to the "reset_counters" file will reset all the above counter - * values. - * - * These statistical counters are implemented as per-cpu variables which are - * summed and computed whenever the corresponding debugfs files are read. This - * minimizes added overhead making the counters usable even in a production - * environment. - * - * There may be slight difference between pv_kick_wake and pv_kick_unlock. - */ -enum qlock_stats { - qstat_pv_hash_hops, - qstat_pv_kick_unlock, - qstat_pv_kick_wake, - qstat_pv_latency_kick, - qstat_pv_latency_wake, - qstat_pv_lock_stealing, - qstat_pv_spurious_wakeup, - qstat_pv_wait_again, - qstat_pv_wait_early, - qstat_pv_wait_head, - qstat_pv_wait_node, - qstat_lock_pending, - qstat_lock_slowpath, - qstat_lock_use_node2, - qstat_lock_use_node3, - qstat_lock_use_node4, - qstat_lock_no_node, - qstat_num, /* Total number of statistical counters */ - qstat_reset_cnts = qstat_num, -}; +#include "lock_events.h" -#ifdef CONFIG_QUEUED_LOCK_STAT +#ifdef CONFIG_LOCK_EVENT_COUNTS +#ifdef CONFIG_PARAVIRT_SPINLOCKS /* - * Collect pvqspinlock statistics + * Collect pvqspinlock locking event counts */ -#include <linux/debugfs.h> #include <linux/sched.h> #include <linux/sched/clock.h> #include <linux/fs.h> -static const char * const qstat_names[qstat_num + 1] = { - [qstat_pv_hash_hops] = "pv_hash_hops", - [qstat_pv_kick_unlock] = "pv_kick_unlock", - [qstat_pv_kick_wake] = "pv_kick_wake", - [qstat_pv_spurious_wakeup] = "pv_spurious_wakeup", - [qstat_pv_latency_kick] = "pv_latency_kick", - [qstat_pv_latency_wake] = "pv_latency_wake", - [qstat_pv_lock_stealing] = "pv_lock_stealing", - [qstat_pv_wait_again] = "pv_wait_again", - [qstat_pv_wait_early] = "pv_wait_early", - [qstat_pv_wait_head] = "pv_wait_head", - [qstat_pv_wait_node] = "pv_wait_node", - [qstat_lock_pending] = "lock_pending", - [qstat_lock_slowpath] = "lock_slowpath", - [qstat_lock_use_node2] = "lock_use_node2", - [qstat_lock_use_node3] = "lock_use_node3", - [qstat_lock_use_node4] = "lock_use_node4", - [qstat_lock_no_node] = "lock_no_node", - [qstat_reset_cnts] = "reset_counters", -}; +#define EVENT_COUNT(ev) lockevents[LOCKEVENT_ ## ev] /* - * Per-cpu counters + * PV specific per-cpu counter */ -static DEFINE_PER_CPU(unsigned long, qstats[qstat_num]); static DEFINE_PER_CPU(u64, pv_kick_time); /* - * Function to read and return the qlock statistical counter values + * Function to read and return the PV qspinlock counts. * * The following counters are handled specially: - * 1. qstat_pv_latency_kick + * 1. pv_latency_kick * Average kick latency (ns) = pv_latency_kick/pv_kick_unlock - * 2. qstat_pv_latency_wake + * 2. pv_latency_wake * Average wake latency (ns) = pv_latency_wake/pv_kick_wake - * 3. qstat_pv_hash_hops + * 3. pv_hash_hops * Average hops/hash = pv_hash_hops/pv_kick_unlock */ -static ssize_t qstat_read(struct file *file, char __user *user_buf, - size_t count, loff_t *ppos) +ssize_t lockevent_read(struct file *file, char __user *user_buf, + size_t count, loff_t *ppos) { char buf[64]; - int cpu, counter, len; - u64 stat = 0, kicks = 0; + int cpu, id, len; + u64 sum = 0, kicks = 0; /* * Get the counter ID stored in file->f_inode->i_private */ - counter = (long)file_inode(file)->i_private; + id = (long)file_inode(file)->i_private; - if (counter >= qstat_num) + if (id >= lockevent_num) return -EBADF; for_each_possible_cpu(cpu) { - stat += per_cpu(qstats[counter], cpu); + sum += per_cpu(lockevents[id], cpu); /* - * Need to sum additional counter for some of them + * Need to sum additional counters for some of them */ - switch (counter) { + switch (id) { - case qstat_pv_latency_kick: - case qstat_pv_hash_hops: - kicks += per_cpu(qstats[qstat_pv_kick_unlock], cpu); + case LOCKEVENT_pv_latency_kick: + case LOCKEVENT_pv_hash_hops: + kicks += per_cpu(EVENT_COUNT(pv_kick_unlock), cpu); break; - case qstat_pv_latency_wake: - kicks += per_cpu(qstats[qstat_pv_kick_wake], cpu); + case LOCKEVENT_pv_latency_wake: + kicks += per_cpu(EVENT_COUNT(pv_kick_wake), cpu); break; } } - if (counter == qstat_pv_hash_hops) { + if (id == LOCKEVENT_pv_hash_hops) { u64 frac = 0; if (kicks) { - frac = 100ULL * do_div(stat, kicks); + frac = 100ULL * do_div(sum, kicks); frac = DIV_ROUND_CLOSEST_ULL(frac, kicks); } /* * Return a X.XX decimal number */ - len = snprintf(buf, sizeof(buf) - 1, "%llu.%02llu\n", stat, frac); + len = snprintf(buf, sizeof(buf) - 1, "%llu.%02llu\n", + sum, frac); } else { /* * Round to the nearest ns */ - if ((counter == qstat_pv_latency_kick) || - (counter == qstat_pv_latency_wake)) { + if ((id == LOCKEVENT_pv_latency_kick) || + (id == LOCKEVENT_pv_latency_wake)) { if (kicks) - stat = DIV_ROUND_CLOSEST_ULL(stat, kicks); + sum = DIV_ROUND_CLOSEST_ULL(sum, kicks); } - len = snprintf(buf, sizeof(buf) - 1, "%llu\n", stat); + len = snprintf(buf, sizeof(buf) - 1, "%llu\n", sum); } return simple_read_from_buffer(user_buf, count, ppos, buf, len); } /* - * Function to handle write request - * - * When counter = reset_cnts, reset all the counter values. - * Since the counter updates aren't atomic, the resetting is done twice - * to make sure that the counters are very likely to be all cleared. - */ -static ssize_t qstat_write(struct file *file, const char __user *user_buf, - size_t count, loff_t *ppos) -{ - int cpu; - - /* - * Get the counter ID stored in file->f_inode->i_private - */ - if ((long)file_inode(file)->i_private != qstat_reset_cnts) - return count; - - for_each_possible_cpu(cpu) { - int i; - unsigned long *ptr = per_cpu_ptr(qstats, cpu); - - for (i = 0 ; i < qstat_num; i++) - WRITE_ONCE(ptr[i], 0); - } - return count; -} - -/* - * Debugfs data structures - */ -static const struct file_operations fops_qstat = { - .read = qstat_read, - .write = qstat_write, - .llseek = default_llseek, -}; - -/* - * Initialize debugfs for the qspinlock statistical counters - */ -static int __init init_qspinlock_stat(void) -{ - struct dentry *d_qstat = debugfs_create_dir("qlockstat", NULL); - int i; - - if (!d_qstat) - goto out; - - /* - * Create the debugfs files - * - * As reading from and writing to the stat files can be slow, only - * root is allowed to do the read/write to limit impact to system - * performance. - */ - for (i = 0; i < qstat_num; i++) - if (!debugfs_create_file(qstat_names[i], 0400, d_qstat, - (void *)(long)i, &fops_qstat)) - goto fail_undo; - - if (!debugfs_create_file(qstat_names[qstat_reset_cnts], 0200, d_qstat, - (void *)(long)qstat_reset_cnts, &fops_qstat)) - goto fail_undo; - - return 0; -fail_undo: - debugfs_remove_recursive(d_qstat); -out: - pr_warn("Could not create 'qlockstat' debugfs entries\n"); - return -ENOMEM; -} -fs_initcall(init_qspinlock_stat); - -/* - * Increment the PV qspinlock statistical counters - */ -static inline void qstat_inc(enum qlock_stats stat, bool cond) -{ - if (cond) - this_cpu_inc(qstats[stat]); -} - -/* * PV hash hop count */ -static inline void qstat_hop(int hopcnt) +static inline void lockevent_pv_hop(int hopcnt) { - this_cpu_add(qstats[qstat_pv_hash_hops], hopcnt); + this_cpu_add(EVENT_COUNT(pv_hash_hops), hopcnt); } /* @@ -276,7 +119,7 @@ static inline void __pv_kick(int cpu) per_cpu(pv_kick_time, cpu) = start; pv_kick(cpu); - this_cpu_add(qstats[qstat_pv_latency_kick], sched_clock() - start); + this_cpu_add(EVENT_COUNT(pv_latency_kick), sched_clock() - start); } /* @@ -289,18 +132,19 @@ static inline void __pv_wait(u8 *ptr, u8 val) *pkick_time = 0; pv_wait(ptr, val); if (*pkick_time) { - this_cpu_add(qstats[qstat_pv_latency_wake], + this_cpu_add(EVENT_COUNT(pv_latency_wake), sched_clock() - *pkick_time); - qstat_inc(qstat_pv_kick_wake, true); + lockevent_inc(pv_kick_wake); } } #define pv_kick(c) __pv_kick(c) #define pv_wait(p, v) __pv_wait(p, v) -#else /* CONFIG_QUEUED_LOCK_STAT */ +#endif /* CONFIG_PARAVIRT_SPINLOCKS */ + +#else /* CONFIG_LOCK_EVENT_COUNTS */ -static inline void qstat_inc(enum qlock_stats stat, bool cond) { } -static inline void qstat_hop(int hopcnt) { } +static inline void lockevent_pv_hop(int hopcnt) { } -#endif /* CONFIG_QUEUED_LOCK_STAT */ +#endif /* CONFIG_LOCK_EVENT_COUNTS */ diff --git a/kernel/locking/rwsem-spinlock.c b/kernel/locking/rwsem-spinlock.c deleted file mode 100644 index a7ffb2a96ede..000000000000 --- a/kernel/locking/rwsem-spinlock.c +++ /dev/null @@ -1,339 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* rwsem-spinlock.c: R/W semaphores: contention handling functions for - * generic spinlock implementation - * - * Copyright (c) 2001 David Howells (dhowells@redhat.com). - * - Derived partially from idea by Andrea Arcangeli <andrea@suse.de> - * - Derived also from comments by Linus - */ -#include <linux/rwsem.h> -#include <linux/sched/signal.h> -#include <linux/sched/debug.h> -#include <linux/export.h> - -enum rwsem_waiter_type { - RWSEM_WAITING_FOR_WRITE, - RWSEM_WAITING_FOR_READ -}; - -struct rwsem_waiter { - struct list_head list; - struct task_struct *task; - enum rwsem_waiter_type type; -}; - -int rwsem_is_locked(struct rw_semaphore *sem) -{ - int ret = 1; - unsigned long flags; - - if (raw_spin_trylock_irqsave(&sem->wait_lock, flags)) { - ret = (sem->count != 0); - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - } - return ret; -} -EXPORT_SYMBOL(rwsem_is_locked); - -/* - * initialise the semaphore - */ -void __init_rwsem(struct rw_semaphore *sem, const char *name, - struct lock_class_key *key) -{ -#ifdef CONFIG_DEBUG_LOCK_ALLOC - /* - * Make sure we are not reinitializing a held semaphore: - */ - debug_check_no_locks_freed((void *)sem, sizeof(*sem)); - lockdep_init_map(&sem->dep_map, name, key, 0); -#endif - sem->count = 0; - raw_spin_lock_init(&sem->wait_lock); - INIT_LIST_HEAD(&sem->wait_list); -} -EXPORT_SYMBOL(__init_rwsem); - -/* - * handle the lock release when processes blocked on it that can now run - * - if we come here, then: - * - the 'active count' _reached_ zero - * - the 'waiting count' is non-zero - * - the spinlock must be held by the caller - * - woken process blocks are discarded from the list after having task zeroed - * - writers are only woken if wakewrite is non-zero - */ -static inline struct rw_semaphore * -__rwsem_do_wake(struct rw_semaphore *sem, int wakewrite) -{ - struct rwsem_waiter *waiter; - struct task_struct *tsk; - int woken; - - waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list); - - if (waiter->type == RWSEM_WAITING_FOR_WRITE) { - if (wakewrite) - /* Wake up a writer. Note that we do not grant it the - * lock - it will have to acquire it when it runs. */ - wake_up_process(waiter->task); - goto out; - } - - /* grant an infinite number of read locks to the front of the queue */ - woken = 0; - do { - struct list_head *next = waiter->list.next; - - list_del(&waiter->list); - tsk = waiter->task; - /* - * Make sure we do not wakeup the next reader before - * setting the nil condition to grant the next reader; - * otherwise we could miss the wakeup on the other - * side and end up sleeping again. See the pairing - * in rwsem_down_read_failed(). - */ - smp_mb(); - waiter->task = NULL; - wake_up_process(tsk); - put_task_struct(tsk); - woken++; - if (next == &sem->wait_list) - break; - waiter = list_entry(next, struct rwsem_waiter, list); - } while (waiter->type != RWSEM_WAITING_FOR_WRITE); - - sem->count += woken; - - out: - return sem; -} - -/* - * wake a single writer - */ -static inline struct rw_semaphore * -__rwsem_wake_one_writer(struct rw_semaphore *sem) -{ - struct rwsem_waiter *waiter; - - waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list); - wake_up_process(waiter->task); - - return sem; -} - -/* - * get a read lock on the semaphore - */ -int __sched __down_read_common(struct rw_semaphore *sem, int state) -{ - struct rwsem_waiter waiter; - unsigned long flags; - - raw_spin_lock_irqsave(&sem->wait_lock, flags); - - if (sem->count >= 0 && list_empty(&sem->wait_list)) { - /* granted */ - sem->count++; - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - goto out; - } - - /* set up my own style of waitqueue */ - waiter.task = current; - waiter.type = RWSEM_WAITING_FOR_READ; - get_task_struct(current); - - list_add_tail(&waiter.list, &sem->wait_list); - - /* wait to be given the lock */ - for (;;) { - if (!waiter.task) - break; - if (signal_pending_state(state, current)) - goto out_nolock; - set_current_state(state); - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - schedule(); - raw_spin_lock_irqsave(&sem->wait_lock, flags); - } - - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - out: - return 0; - -out_nolock: - /* - * We didn't take the lock, so that there is a writer, which - * is owner or the first waiter of the sem. If it's a waiter, - * it will be woken by current owner. Not need to wake anybody. - */ - list_del(&waiter.list); - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - return -EINTR; -} - -void __sched __down_read(struct rw_semaphore *sem) -{ - __down_read_common(sem, TASK_UNINTERRUPTIBLE); -} - -int __sched __down_read_killable(struct rw_semaphore *sem) -{ - return __down_read_common(sem, TASK_KILLABLE); -} - -/* - * trylock for reading -- returns 1 if successful, 0 if contention - */ -int __down_read_trylock(struct rw_semaphore *sem) -{ - unsigned long flags; - int ret = 0; - - - raw_spin_lock_irqsave(&sem->wait_lock, flags); - - if (sem->count >= 0 && list_empty(&sem->wait_list)) { - /* granted */ - sem->count++; - ret = 1; - } - - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - - return ret; -} - -/* - * get a write lock on the semaphore - */ -int __sched __down_write_common(struct rw_semaphore *sem, int state) -{ - struct rwsem_waiter waiter; - unsigned long flags; - int ret = 0; - - raw_spin_lock_irqsave(&sem->wait_lock, flags); - - /* set up my own style of waitqueue */ - waiter.task = current; - waiter.type = RWSEM_WAITING_FOR_WRITE; - list_add_tail(&waiter.list, &sem->wait_list); - - /* wait for someone to release the lock */ - for (;;) { - /* - * That is the key to support write lock stealing: allows the - * task already on CPU to get the lock soon rather than put - * itself into sleep and waiting for system woke it or someone - * else in the head of the wait list up. - */ - if (sem->count == 0) - break; - if (signal_pending_state(state, current)) - goto out_nolock; - - set_current_state(state); - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - schedule(); - raw_spin_lock_irqsave(&sem->wait_lock, flags); - } - /* got the lock */ - sem->count = -1; - list_del(&waiter.list); - - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - - return ret; - -out_nolock: - list_del(&waiter.list); - if (!list_empty(&sem->wait_list) && sem->count >= 0) - __rwsem_do_wake(sem, 0); - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - - return -EINTR; -} - -void __sched __down_write(struct rw_semaphore *sem) -{ - __down_write_common(sem, TASK_UNINTERRUPTIBLE); -} - -int __sched __down_write_killable(struct rw_semaphore *sem) -{ - return __down_write_common(sem, TASK_KILLABLE); -} - -/* - * trylock for writing -- returns 1 if successful, 0 if contention - */ -int __down_write_trylock(struct rw_semaphore *sem) -{ - unsigned long flags; - int ret = 0; - - raw_spin_lock_irqsave(&sem->wait_lock, flags); - - if (sem->count == 0) { - /* got the lock */ - sem->count = -1; - ret = 1; - } - - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - - return ret; -} - -/* - * release a read lock on the semaphore - */ -void __up_read(struct rw_semaphore *sem) -{ - unsigned long flags; - - raw_spin_lock_irqsave(&sem->wait_lock, flags); - - if (--sem->count == 0 && !list_empty(&sem->wait_list)) - sem = __rwsem_wake_one_writer(sem); - - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); -} - -/* - * release a write lock on the semaphore - */ -void __up_write(struct rw_semaphore *sem) -{ - unsigned long flags; - - raw_spin_lock_irqsave(&sem->wait_lock, flags); - - sem->count = 0; - if (!list_empty(&sem->wait_list)) - sem = __rwsem_do_wake(sem, 1); - - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); -} - -/* - * downgrade a write lock into a read lock - * - just wake up any readers at the front of the queue - */ -void __downgrade_write(struct rw_semaphore *sem) -{ - unsigned long flags; - - raw_spin_lock_irqsave(&sem->wait_lock, flags); - - sem->count = 1; - if (!list_empty(&sem->wait_list)) - sem = __rwsem_do_wake(sem, 0); - - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); -} - diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c index fbe96341beee..6b3ee9948bf1 100644 --- a/kernel/locking/rwsem-xadd.c +++ b/kernel/locking/rwsem-xadd.c @@ -147,6 +147,7 @@ static void __rwsem_mark_wake(struct rw_semaphore *sem, * will notice the queued writer. */ wake_q_add(wake_q, waiter->task); + lockevent_inc(rwsem_wake_writer); } return; @@ -176,9 +177,8 @@ static void __rwsem_mark_wake(struct rw_semaphore *sem, goto try_reader_grant; } /* - * It is not really necessary to set it to reader-owned here, - * but it gives the spinners an early indication that the - * readers now have the lock. + * Set it to reader-owned to give spinners an early + * indication that readers now have the lock. */ __rwsem_set_reader_owned(sem, waiter->task); } @@ -215,6 +215,7 @@ static void __rwsem_mark_wake(struct rw_semaphore *sem, } adjustment = woken * RWSEM_ACTIVE_READ_BIAS - adjustment; + lockevent_cond_inc(rwsem_wake_reader, woken); if (list_empty(&sem->wait_list)) { /* hit end of list above */ adjustment -= RWSEM_WAITING_BIAS; @@ -225,92 +226,6 @@ static void __rwsem_mark_wake(struct rw_semaphore *sem, } /* - * Wait for the read lock to be granted - */ -static inline struct rw_semaphore __sched * -__rwsem_down_read_failed_common(struct rw_semaphore *sem, int state) -{ - long count, adjustment = -RWSEM_ACTIVE_READ_BIAS; - struct rwsem_waiter waiter; - DEFINE_WAKE_Q(wake_q); - - waiter.task = current; - waiter.type = RWSEM_WAITING_FOR_READ; - - raw_spin_lock_irq(&sem->wait_lock); - if (list_empty(&sem->wait_list)) { - /* - * In case the wait queue is empty and the lock isn't owned - * by a writer, this reader can exit the slowpath and return - * immediately as its RWSEM_ACTIVE_READ_BIAS has already - * been set in the count. - */ - if (atomic_long_read(&sem->count) >= 0) { - raw_spin_unlock_irq(&sem->wait_lock); - return sem; - } - adjustment += RWSEM_WAITING_BIAS; - } - list_add_tail(&waiter.list, &sem->wait_list); - - /* we're now waiting on the lock, but no longer actively locking */ - count = atomic_long_add_return(adjustment, &sem->count); - - /* - * If there are no active locks, wake the front queued process(es). - * - * If there are no writers and we are first in the queue, - * wake our own waiter to join the existing active readers ! - */ - if (count == RWSEM_WAITING_BIAS || - (count > RWSEM_WAITING_BIAS && - adjustment != -RWSEM_ACTIVE_READ_BIAS)) - __rwsem_mark_wake(sem, RWSEM_WAKE_ANY, &wake_q); - - raw_spin_unlock_irq(&sem->wait_lock); - wake_up_q(&wake_q); - - /* wait to be given the lock */ - while (true) { - set_current_state(state); - if (!waiter.task) - break; - if (signal_pending_state(state, current)) { - raw_spin_lock_irq(&sem->wait_lock); - if (waiter.task) - goto out_nolock; - raw_spin_unlock_irq(&sem->wait_lock); - break; - } - schedule(); - } - - __set_current_state(TASK_RUNNING); - return sem; -out_nolock: - list_del(&waiter.list); - if (list_empty(&sem->wait_list)) - atomic_long_add(-RWSEM_WAITING_BIAS, &sem->count); - raw_spin_unlock_irq(&sem->wait_lock); - __set_current_state(TASK_RUNNING); - return ERR_PTR(-EINTR); -} - -__visible struct rw_semaphore * __sched -rwsem_down_read_failed(struct rw_semaphore *sem) -{ - return __rwsem_down_read_failed_common(sem, TASK_UNINTERRUPTIBLE); -} -EXPORT_SYMBOL(rwsem_down_read_failed); - -__visible struct rw_semaphore * __sched -rwsem_down_read_failed_killable(struct rw_semaphore *sem) -{ - return __rwsem_down_read_failed_common(sem, TASK_KILLABLE); -} -EXPORT_SYMBOL(rwsem_down_read_failed_killable); - -/* * This function must be called with the sem->wait_lock held to prevent * race conditions between checking the rwsem wait list and setting the * sem->count accordingly. @@ -346,21 +261,17 @@ static inline bool rwsem_try_write_lock(long count, struct rw_semaphore *sem) */ static inline bool rwsem_try_write_lock_unqueued(struct rw_semaphore *sem) { - long old, count = atomic_long_read(&sem->count); - - while (true) { - if (!(count == 0 || count == RWSEM_WAITING_BIAS)) - return false; + long count = atomic_long_read(&sem->count); - old = atomic_long_cmpxchg_acquire(&sem->count, count, - count + RWSEM_ACTIVE_WRITE_BIAS); - if (old == count) { + while (!count || count == RWSEM_WAITING_BIAS) { + if (atomic_long_try_cmpxchg_acquire(&sem->count, &count, + count + RWSEM_ACTIVE_WRITE_BIAS)) { rwsem_set_owner(sem); + lockevent_inc(rwsem_opt_wlock); return true; } - - count = old; } + return false; } static inline bool owner_on_cpu(struct task_struct *owner) @@ -481,6 +392,7 @@ static bool rwsem_optimistic_spin(struct rw_semaphore *sem) osq_unlock(&sem->osq); done: preempt_enable(); + lockevent_cond_inc(rwsem_opt_fail, !taken); return taken; } @@ -505,6 +417,97 @@ static inline bool rwsem_has_spinner(struct rw_semaphore *sem) #endif /* + * Wait for the read lock to be granted + */ +static inline struct rw_semaphore __sched * +__rwsem_down_read_failed_common(struct rw_semaphore *sem, int state) +{ + long count, adjustment = -RWSEM_ACTIVE_READ_BIAS; + struct rwsem_waiter waiter; + DEFINE_WAKE_Q(wake_q); + + waiter.task = current; + waiter.type = RWSEM_WAITING_FOR_READ; + + raw_spin_lock_irq(&sem->wait_lock); + if (list_empty(&sem->wait_list)) { + /* + * In case the wait queue is empty and the lock isn't owned + * by a writer, this reader can exit the slowpath and return + * immediately as its RWSEM_ACTIVE_READ_BIAS has already + * been set in the count. + */ + if (atomic_long_read(&sem->count) >= 0) { + raw_spin_unlock_irq(&sem->wait_lock); + rwsem_set_reader_owned(sem); + lockevent_inc(rwsem_rlock_fast); + return sem; + } + adjustment += RWSEM_WAITING_BIAS; + } + list_add_tail(&waiter.list, &sem->wait_list); + + /* we're now waiting on the lock, but no longer actively locking */ + count = atomic_long_add_return(adjustment, &sem->count); + + /* + * If there are no active locks, wake the front queued process(es). + * + * If there are no writers and we are first in the queue, + * wake our own waiter to join the existing active readers ! + */ + if (count == RWSEM_WAITING_BIAS || + (count > RWSEM_WAITING_BIAS && + adjustment != -RWSEM_ACTIVE_READ_BIAS)) + __rwsem_mark_wake(sem, RWSEM_WAKE_ANY, &wake_q); + + raw_spin_unlock_irq(&sem->wait_lock); + wake_up_q(&wake_q); + + /* wait to be given the lock */ + while (true) { + set_current_state(state); + if (!waiter.task) + break; + if (signal_pending_state(state, current)) { + raw_spin_lock_irq(&sem->wait_lock); + if (waiter.task) + goto out_nolock; + raw_spin_unlock_irq(&sem->wait_lock); + break; + } + schedule(); + lockevent_inc(rwsem_sleep_reader); + } + + __set_current_state(TASK_RUNNING); + lockevent_inc(rwsem_rlock); + return sem; +out_nolock: + list_del(&waiter.list); + if (list_empty(&sem->wait_list)) + atomic_long_add(-RWSEM_WAITING_BIAS, &sem->count); + raw_spin_unlock_irq(&sem->wait_lock); + __set_current_state(TASK_RUNNING); + lockevent_inc(rwsem_rlock_fail); + return ERR_PTR(-EINTR); +} + +__visible struct rw_semaphore * __sched +rwsem_down_read_failed(struct rw_semaphore *sem) +{ + return __rwsem_down_read_failed_common(sem, TASK_UNINTERRUPTIBLE); +} +EXPORT_SYMBOL(rwsem_down_read_failed); + +__visible struct rw_semaphore * __sched +rwsem_down_read_failed_killable(struct rw_semaphore *sem) +{ + return __rwsem_down_read_failed_common(sem, TASK_KILLABLE); +} +EXPORT_SYMBOL(rwsem_down_read_failed_killable); + +/* * Wait until we successfully acquire the write lock */ static inline struct rw_semaphore * @@ -580,6 +583,7 @@ __rwsem_down_write_failed_common(struct rw_semaphore *sem, int state) goto out_nolock; schedule(); + lockevent_inc(rwsem_sleep_writer); set_current_state(state); } while ((count = atomic_long_read(&sem->count)) & RWSEM_ACTIVE_MASK); @@ -588,6 +592,7 @@ __rwsem_down_write_failed_common(struct rw_semaphore *sem, int state) __set_current_state(TASK_RUNNING); list_del(&waiter.list); raw_spin_unlock_irq(&sem->wait_lock); + lockevent_inc(rwsem_wlock); return ret; @@ -601,6 +606,7 @@ out_nolock: __rwsem_mark_wake(sem, RWSEM_WAKE_ANY, &wake_q); raw_spin_unlock_irq(&sem->wait_lock); wake_up_q(&wake_q); + lockevent_inc(rwsem_wlock_fail); return ERR_PTR(-EINTR); } diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index e586f0d03ad3..ccbf18f560ff 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -24,7 +24,6 @@ void __sched down_read(struct rw_semaphore *sem) rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_); LOCK_CONTENDED(sem, __down_read_trylock, __down_read); - rwsem_set_reader_owned(sem); } EXPORT_SYMBOL(down_read); @@ -39,7 +38,6 @@ int __sched down_read_killable(struct rw_semaphore *sem) return -EINTR; } - rwsem_set_reader_owned(sem); return 0; } @@ -52,10 +50,8 @@ int down_read_trylock(struct rw_semaphore *sem) { int ret = __down_read_trylock(sem); - if (ret == 1) { + if (ret == 1) rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_); - rwsem_set_reader_owned(sem); - } return ret; } @@ -70,7 +66,6 @@ void __sched down_write(struct rw_semaphore *sem) rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_); LOCK_CONTENDED(sem, __down_write_trylock, __down_write); - rwsem_set_owner(sem); } EXPORT_SYMBOL(down_write); @@ -88,7 +83,6 @@ int __sched down_write_killable(struct rw_semaphore *sem) return -EINTR; } - rwsem_set_owner(sem); return 0; } @@ -101,10 +95,8 @@ int down_write_trylock(struct rw_semaphore *sem) { int ret = __down_write_trylock(sem); - if (ret == 1) { + if (ret == 1) rwsem_acquire(&sem->dep_map, 0, 1, _RET_IP_); - rwsem_set_owner(sem); - } return ret; } @@ -117,9 +109,7 @@ EXPORT_SYMBOL(down_write_trylock); void up_read(struct rw_semaphore *sem) { rwsem_release(&sem->dep_map, 1, _RET_IP_); - DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & RWSEM_READER_OWNED)); - rwsem_clear_reader_owned(sem); __up_read(sem); } @@ -131,9 +121,7 @@ EXPORT_SYMBOL(up_read); void up_write(struct rw_semaphore *sem) { rwsem_release(&sem->dep_map, 1, _RET_IP_); - DEBUG_RWSEMS_WARN_ON(sem->owner != current); - rwsem_clear_owner(sem); __up_write(sem); } @@ -145,9 +133,7 @@ EXPORT_SYMBOL(up_write); void downgrade_write(struct rw_semaphore *sem) { lock_downgrade(&sem->dep_map, _RET_IP_); - DEBUG_RWSEMS_WARN_ON(sem->owner != current); - rwsem_set_reader_owned(sem); __downgrade_write(sem); } @@ -161,7 +147,6 @@ void down_read_nested(struct rw_semaphore *sem, int subclass) rwsem_acquire_read(&sem->dep_map, subclass, 0, _RET_IP_); LOCK_CONTENDED(sem, __down_read_trylock, __down_read); - rwsem_set_reader_owned(sem); } EXPORT_SYMBOL(down_read_nested); @@ -172,7 +157,6 @@ void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest) rwsem_acquire_nest(&sem->dep_map, 0, 0, nest, _RET_IP_); LOCK_CONTENDED(sem, __down_write_trylock, __down_write); - rwsem_set_owner(sem); } EXPORT_SYMBOL(_down_write_nest_lock); @@ -193,7 +177,6 @@ void down_write_nested(struct rw_semaphore *sem, int subclass) rwsem_acquire(&sem->dep_map, subclass, 0, _RET_IP_); LOCK_CONTENDED(sem, __down_write_trylock, __down_write); - rwsem_set_owner(sem); } EXPORT_SYMBOL(down_write_nested); @@ -208,7 +191,6 @@ int __sched down_write_killable_nested(struct rw_semaphore *sem, int subclass) return -EINTR; } - rwsem_set_owner(sem); return 0; } @@ -216,7 +198,8 @@ EXPORT_SYMBOL(down_write_killable_nested); void up_read_non_owner(struct rw_semaphore *sem) { - DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & RWSEM_READER_OWNED)); + DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & RWSEM_READER_OWNED), + sem); __up_read(sem); } diff --git a/kernel/locking/rwsem.h b/kernel/locking/rwsem.h index bad2bca0268b..64877f5294e3 100644 --- a/kernel/locking/rwsem.h +++ b/kernel/locking/rwsem.h @@ -23,15 +23,44 @@ * is involved. Ideally we would like to track all the readers that own * a rwsem, but the overhead is simply too big. */ +#include "lock_events.h" + #define RWSEM_READER_OWNED (1UL << 0) #define RWSEM_ANONYMOUSLY_OWNED (1UL << 1) #ifdef CONFIG_DEBUG_RWSEMS -# define DEBUG_RWSEMS_WARN_ON(c) DEBUG_LOCKS_WARN_ON(c) +# define DEBUG_RWSEMS_WARN_ON(c, sem) do { \ + if (!debug_locks_silent && \ + WARN_ONCE(c, "DEBUG_RWSEMS_WARN_ON(%s): count = 0x%lx, owner = 0x%lx, curr 0x%lx, list %sempty\n",\ + #c, atomic_long_read(&(sem)->count), \ + (long)((sem)->owner), (long)current, \ + list_empty(&(sem)->wait_list) ? "" : "not ")) \ + debug_locks_off(); \ + } while (0) +#else +# define DEBUG_RWSEMS_WARN_ON(c, sem) +#endif + +/* + * R/W semaphores originally for PPC using the stuff in lib/rwsem.c. + * Adapted largely from include/asm-i386/rwsem.h + * by Paul Mackerras <paulus@samba.org>. + */ + +/* + * the semaphore definition + */ +#ifdef CONFIG_64BIT +# define RWSEM_ACTIVE_MASK 0xffffffffL #else -# define DEBUG_RWSEMS_WARN_ON(c) +# define RWSEM_ACTIVE_MASK 0x0000ffffL #endif +#define RWSEM_ACTIVE_BIAS 0x00000001L +#define RWSEM_WAITING_BIAS (-RWSEM_ACTIVE_MASK-1) +#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS +#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) + #ifdef CONFIG_RWSEM_SPIN_ON_OWNER /* * All writes to owner are protected by WRITE_ONCE() to make sure that @@ -132,3 +161,144 @@ static inline void rwsem_clear_reader_owned(struct rw_semaphore *sem) { } #endif + +extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem); +extern struct rw_semaphore *rwsem_down_read_failed_killable(struct rw_semaphore *sem); +extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem); +extern struct rw_semaphore *rwsem_down_write_failed_killable(struct rw_semaphore *sem); +extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem); +extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem); + +/* + * lock for reading + */ +static inline void __down_read(struct rw_semaphore *sem) +{ + if (unlikely(atomic_long_inc_return_acquire(&sem->count) <= 0)) { + rwsem_down_read_failed(sem); + DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & + RWSEM_READER_OWNED), sem); + } else { + rwsem_set_reader_owned(sem); + } +} + +static inline int __down_read_killable(struct rw_semaphore *sem) +{ + if (unlikely(atomic_long_inc_return_acquire(&sem->count) <= 0)) { + if (IS_ERR(rwsem_down_read_failed_killable(sem))) + return -EINTR; + DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & + RWSEM_READER_OWNED), sem); + } else { + rwsem_set_reader_owned(sem); + } + return 0; +} + +static inline int __down_read_trylock(struct rw_semaphore *sem) +{ + /* + * Optimize for the case when the rwsem is not locked at all. + */ + long tmp = RWSEM_UNLOCKED_VALUE; + + lockevent_inc(rwsem_rtrylock); + do { + if (atomic_long_try_cmpxchg_acquire(&sem->count, &tmp, + tmp + RWSEM_ACTIVE_READ_BIAS)) { + rwsem_set_reader_owned(sem); + return 1; + } + } while (tmp >= 0); + return 0; +} + +/* + * lock for writing + */ +static inline void __down_write(struct rw_semaphore *sem) +{ + long tmp; + + tmp = atomic_long_add_return_acquire(RWSEM_ACTIVE_WRITE_BIAS, + &sem->count); + if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS)) + rwsem_down_write_failed(sem); + rwsem_set_owner(sem); +} + +static inline int __down_write_killable(struct rw_semaphore *sem) +{ + long tmp; + + tmp = atomic_long_add_return_acquire(RWSEM_ACTIVE_WRITE_BIAS, + &sem->count); + if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS)) + if (IS_ERR(rwsem_down_write_failed_killable(sem))) + return -EINTR; + rwsem_set_owner(sem); + return 0; +} + +static inline int __down_write_trylock(struct rw_semaphore *sem) +{ + long tmp; + + lockevent_inc(rwsem_wtrylock); + tmp = atomic_long_cmpxchg_acquire(&sem->count, RWSEM_UNLOCKED_VALUE, + RWSEM_ACTIVE_WRITE_BIAS); + if (tmp == RWSEM_UNLOCKED_VALUE) { + rwsem_set_owner(sem); + return true; + } + return false; +} + +/* + * unlock after reading + */ +static inline void __up_read(struct rw_semaphore *sem) +{ + long tmp; + + DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & RWSEM_READER_OWNED), + sem); + rwsem_clear_reader_owned(sem); + tmp = atomic_long_dec_return_release(&sem->count); + if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)) + rwsem_wake(sem); +} + +/* + * unlock after writing + */ +static inline void __up_write(struct rw_semaphore *sem) +{ + DEBUG_RWSEMS_WARN_ON(sem->owner != current, sem); + rwsem_clear_owner(sem); + if (unlikely(atomic_long_sub_return_release(RWSEM_ACTIVE_WRITE_BIAS, + &sem->count) < 0)) + rwsem_wake(sem); +} + +/* + * downgrade write lock to read lock + */ +static inline void __downgrade_write(struct rw_semaphore *sem) +{ + long tmp; + + /* + * When downgrading from exclusive to shared ownership, + * anything inside the write-locked region cannot leak + * into the read side. In contrast, anything in the + * read-locked region is ok to be re-ordered into the + * write side. As such, rely on RELEASE semantics. + */ + DEBUG_RWSEMS_WARN_ON(sem->owner != current, sem); + tmp = atomic_long_add_return_release(-RWSEM_WAITING_BIAS, &sem->count); + rwsem_set_reader_owned(sem); + if (tmp < 0) + rwsem_downgrade_wake(sem); +} |