From fb1c8f93d869b34cacb8b8932e2b83d96a19d720 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sat, 10 Sep 2005 00:25:56 -0700 Subject: [PATCH] spinlock consolidation This patch (written by me and also containing many suggestions of Arjan van de Ven) does a major cleanup of the spinlock code. It does the following things: - consolidates and enhances the spinlock/rwlock debugging code - simplifies the asm/spinlock.h files - encapsulates the raw spinlock type and moves generic spinlock features (such as ->break_lock) into the generic code. - cleans up the spinlock code hierarchy to get rid of the spaghetti. Most notably there's now only a single variant of the debugging code, located in lib/spinlock_debug.c. (previously we had one SMP debugging variant per architecture, plus a separate generic one for UP builds) Also, i've enhanced the rwlock debugging facility, it will now track write-owners. There is new spinlock-owner/CPU-tracking on SMP builds too. All locks have lockup detection now, which will work for both soft and hard spin/rwlock lockups. The arch-level include files now only contain the minimally necessary subset of the spinlock code - all the rest that can be generalized now lives in the generic headers: include/asm-i386/spinlock_types.h | 16 include/asm-x86_64/spinlock_types.h | 16 I have also split up the various spinlock variants into separate files, making it easier to see which does what. The new layout is: SMP | UP ----------------------------|----------------------------------- asm/spinlock_types_smp.h | linux/spinlock_types_up.h linux/spinlock_types.h | linux/spinlock_types.h asm/spinlock_smp.h | linux/spinlock_up.h linux/spinlock_api_smp.h | linux/spinlock_api_up.h linux/spinlock.h | linux/spinlock.h /* * here's the role of the various spinlock/rwlock related include files: * * on SMP builds: * * asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the * initializers * * linux/spinlock_types.h: * defines the generic type and initializers * * asm/spinlock.h: contains the __raw_spin_*()/etc. lowlevel * implementations, mostly inline assembly code * * (also included on UP-debug builds:) * * linux/spinlock_api_smp.h: * contains the prototypes for the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. * * on UP builds: * * linux/spinlock_type_up.h: * contains the generic, simplified UP spinlock type. * (which is an empty structure on non-debug builds) * * linux/spinlock_types.h: * defines the generic type and initializers * * linux/spinlock_up.h: * contains the __raw_spin_*()/etc. version of UP * builds. (which are NOPs on non-debug, non-preempt * builds) * * (included on UP-non-debug builds:) * * linux/spinlock_api_up.h: * builds the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. */ All SMP and UP architectures are converted by this patch. arm, i386, ia64, ppc, ppc64, s390/s390x, x64 was build-tested via crosscompilers. m32r, mips, sh, sparc, have not been tested yet, but should be mostly fine. From: Grant Grundler Booted and lightly tested on a500-44 (64-bit, SMP kernel, dual CPU). Builds 32-bit SMP kernel (not booted or tested). I did not try to build non-SMP kernels. That should be trivial to fix up later if necessary. I converted bit ops atomic_hash lock to raw_spinlock_t. Doing so avoids some ugly nesting of linux/*.h and asm/*.h files. Those particular locks are well tested and contained entirely inside arch specific code. I do NOT expect any new issues to arise with them. If someone does ever need to use debug/metrics with them, then they will need to unravel this hairball between spinlocks, atomic ops, and bit ops that exist only because parisc has exactly one atomic instruction: LDCW (load and clear word). From: "Luck, Tony" ia64 fix Signed-off-by: Ingo Molnar Signed-off-by: Arjan van de Ven Signed-off-by: Grant Grundler Cc: Matthew Wilcox Signed-off-by: Hirokazu Takata Signed-off-by: Mikael Pettersson Signed-off-by: Benoit Boissinot Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/Makefile | 1 + lib/dec_and_lock.c | 3 - lib/kernel_lock.c | 3 +- lib/spinlock_debug.c | 257 +++++++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 259 insertions(+), 5 deletions(-) create mode 100644 lib/spinlock_debug.c (limited to 'lib') diff --git a/lib/Makefile b/lib/Makefile index d9c38ba05e7b..44a46750690a 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -16,6 +16,7 @@ CFLAGS_kobject.o += -DDEBUG CFLAGS_kobject_uevent.o += -DDEBUG endif +obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o lib-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o lib-$(CONFIG_SEMAPHORE_SLEEPERS) += semaphore-sleepers.o diff --git a/lib/dec_and_lock.c b/lib/dec_and_lock.c index 6658d81e1836..2377af057d09 100644 --- a/lib/dec_and_lock.c +++ b/lib/dec_and_lock.c @@ -25,8 +25,6 @@ * this is trivially done efficiently using a load-locked * store-conditional approach, for example. */ - -#ifndef ATOMIC_DEC_AND_LOCK int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock) { spin_lock(lock); @@ -37,4 +35,3 @@ int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock) } EXPORT_SYMBOL(_atomic_dec_and_lock); -#endif diff --git a/lib/kernel_lock.c b/lib/kernel_lock.c index bd2bc5d887b8..cb5490ec00f2 100644 --- a/lib/kernel_lock.c +++ b/lib/kernel_lock.c @@ -177,8 +177,7 @@ static inline void __lock_kernel(void) static inline void __unlock_kernel(void) { - _raw_spin_unlock(&kernel_flag); - preempt_enable(); + spin_unlock(&kernel_flag); } /* diff --git a/lib/spinlock_debug.c b/lib/spinlock_debug.c new file mode 100644 index 000000000000..906ad101eab3 --- /dev/null +++ b/lib/spinlock_debug.c @@ -0,0 +1,257 @@ +/* + * Copyright 2005, Red Hat, Inc., Ingo Molnar + * Released under the General Public License (GPL). + * + * This file contains the spinlock/rwlock implementations for + * DEBUG_SPINLOCK. + */ + +#include +#include +#include +#include + +static void spin_bug(spinlock_t *lock, const char *msg) +{ + static long print_once = 1; + struct task_struct *owner = NULL; + + if (xchg(&print_once, 0)) { + if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT) + owner = lock->owner; + printk("BUG: spinlock %s on CPU#%d, %s/%d\n", + msg, smp_processor_id(), current->comm, current->pid); + printk(" lock: %p, .magic: %08x, .owner: %s/%d, .owner_cpu: %d\n", + lock, lock->magic, + owner ? owner->comm : "", + owner ? owner->pid : -1, + lock->owner_cpu); + dump_stack(); +#ifdef CONFIG_SMP + /* + * We cannot continue on SMP: + */ +// panic("bad locking"); +#endif + } +} + +#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg) + +static inline void debug_spin_lock_before(spinlock_t *lock) +{ + SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic"); + SPIN_BUG_ON(lock->owner == current, lock, "recursion"); + SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(), + lock, "cpu recursion"); +} + +static inline void debug_spin_lock_after(spinlock_t *lock) +{ + lock->owner_cpu = raw_smp_processor_id(); + lock->owner = current; +} + +static inline void debug_spin_unlock(spinlock_t *lock) +{ + SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic"); + SPIN_BUG_ON(!spin_is_locked(lock), lock, "already unlocked"); + SPIN_BUG_ON(lock->owner != current, lock, "wrong owner"); + SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(), + lock, "wrong CPU"); + lock->owner = SPINLOCK_OWNER_INIT; + lock->owner_cpu = -1; +} + +static void __spin_lock_debug(spinlock_t *lock) +{ + int print_once = 1; + u64 i; + + for (;;) { + for (i = 0; i < loops_per_jiffy * HZ; i++) { + cpu_relax(); + if (__raw_spin_trylock(&lock->raw_lock)) + return; + } + /* lockup suspected: */ + if (print_once) { + print_once = 0; + printk("BUG: spinlock lockup on CPU#%d, %s/%d, %p\n", + smp_processor_id(), current->comm, current->pid, + lock); + dump_stack(); + } + } +} + +void _raw_spin_lock(spinlock_t *lock) +{ + debug_spin_lock_before(lock); + if (unlikely(!__raw_spin_trylock(&lock->raw_lock))) + __spin_lock_debug(lock); + debug_spin_lock_after(lock); +} + +int _raw_spin_trylock(spinlock_t *lock) +{ + int ret = __raw_spin_trylock(&lock->raw_lock); + + if (ret) + debug_spin_lock_after(lock); +#ifndef CONFIG_SMP + /* + * Must not happen on UP: + */ + SPIN_BUG_ON(!ret, lock, "trylock failure on UP"); +#endif + return ret; +} + +void _raw_spin_unlock(spinlock_t *lock) +{ + debug_spin_unlock(lock); + __raw_spin_unlock(&lock->raw_lock); +} + +static void rwlock_bug(rwlock_t *lock, const char *msg) +{ + static long print_once = 1; + + if (xchg(&print_once, 0)) { + printk("BUG: rwlock %s on CPU#%d, %s/%d, %p\n", msg, + smp_processor_id(), current->comm, current->pid, lock); + dump_stack(); +#ifdef CONFIG_SMP + /* + * We cannot continue on SMP: + */ + panic("bad locking"); +#endif + } +} + +#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg) + +static void __read_lock_debug(rwlock_t *lock) +{ + int print_once = 1; + u64 i; + + for (;;) { + for (i = 0; i < loops_per_jiffy * HZ; i++) { + cpu_relax(); + if (__raw_read_trylock(&lock->raw_lock)) + return; + } + /* lockup suspected: */ + if (print_once) { + print_once = 0; + printk("BUG: read-lock lockup on CPU#%d, %s/%d, %p\n", + smp_processor_id(), current->comm, current->pid, + lock); + dump_stack(); + } + } +} + +void _raw_read_lock(rwlock_t *lock) +{ + RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); + if (unlikely(!__raw_read_trylock(&lock->raw_lock))) + __read_lock_debug(lock); +} + +int _raw_read_trylock(rwlock_t *lock) +{ + int ret = __raw_read_trylock(&lock->raw_lock); + +#ifndef CONFIG_SMP + /* + * Must not happen on UP: + */ + RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP"); +#endif + return ret; +} + +void _raw_read_unlock(rwlock_t *lock) +{ + RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); + __raw_read_unlock(&lock->raw_lock); +} + +static inline void debug_write_lock_before(rwlock_t *lock) +{ + RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); + RWLOCK_BUG_ON(lock->owner == current, lock, "recursion"); + RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(), + lock, "cpu recursion"); +} + +static inline void debug_write_lock_after(rwlock_t *lock) +{ + lock->owner_cpu = raw_smp_processor_id(); + lock->owner = current; +} + +static inline void debug_write_unlock(rwlock_t *lock) +{ + RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); + RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner"); + RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(), + lock, "wrong CPU"); + lock->owner = SPINLOCK_OWNER_INIT; + lock->owner_cpu = -1; +} + +static void __write_lock_debug(rwlock_t *lock) +{ + int print_once = 1; + u64 i; + + for (;;) { + for (i = 0; i < loops_per_jiffy * HZ; i++) { + cpu_relax(); + if (__raw_write_trylock(&lock->raw_lock)) + return; + } + /* lockup suspected: */ + if (print_once) { + print_once = 0; + printk("BUG: write-lock lockup on CPU#%d, %s/%d, %p\n", + smp_processor_id(), current->comm, current->pid, + lock); + dump_stack(); + } + } +} + +void _raw_write_lock(rwlock_t *lock) +{ + debug_write_lock_before(lock); + if (unlikely(!__raw_write_trylock(&lock->raw_lock))) + __write_lock_debug(lock); + debug_write_lock_after(lock); +} + +int _raw_write_trylock(rwlock_t *lock) +{ + int ret = __raw_write_trylock(&lock->raw_lock); + + if (ret) + debug_write_lock_after(lock); +#ifndef CONFIG_SMP + /* + * Must not happen on UP: + */ + RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP"); +#endif + return ret; +} + +void _raw_write_unlock(rwlock_t *lock) +{ + debug_write_unlock(lock); + __raw_write_unlock(&lock->raw_lock); +} -- cgit v1.2.3