diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Makefile | 4 | ||||
| -rw-r--r-- | lib/percpu-rwsem.c | 165 | ||||
| -rw-r--r-- | lib/rwsem-spinlock.c | 296 | ||||
| -rw-r--r-- | lib/rwsem.c | 293 | ||||
| -rw-r--r-- | lib/spinlock_debug.c | 302 |
5 files changed, 0 insertions, 1060 deletions
diff --git a/lib/Makefile b/lib/Makefile index bb016e116ba4..d480a8c92385 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -42,10 +42,6 @@ obj-$(CONFIG_GENERIC_PCI_IOMAP) += pci_iomap.o obj-$(CONFIG_HAS_IOMEM) += iomap_copy.o devres.o obj-$(CONFIG_CHECK_SIGNATURE) += check_signature.o obj-$(CONFIG_DEBUG_LOCKING_API_SELFTESTS) += locking-selftest.o -obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o -lib-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o -lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o -lib-$(CONFIG_PERCPU_RWSEM) += percpu-rwsem.o CFLAGS_hweight.o = $(subst $(quote),,$(CONFIG_ARCH_HWEIGHT_CFLAGS)) obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o diff --git a/lib/percpu-rwsem.c b/lib/percpu-rwsem.c deleted file mode 100644 index 652a8ee8efe9..000000000000 --- a/lib/percpu-rwsem.c +++ /dev/null @@ -1,165 +0,0 @@ -#include <linux/atomic.h> -#include <linux/rwsem.h> -#include <linux/percpu.h> -#include <linux/wait.h> -#include <linux/lockdep.h> -#include <linux/percpu-rwsem.h> -#include <linux/rcupdate.h> -#include <linux/sched.h> -#include <linux/errno.h> - -int __percpu_init_rwsem(struct percpu_rw_semaphore *brw, - const char *name, struct lock_class_key *rwsem_key) -{ - brw->fast_read_ctr = alloc_percpu(int); - if (unlikely(!brw->fast_read_ctr)) - return -ENOMEM; - - /* ->rw_sem represents the whole percpu_rw_semaphore for lockdep */ - __init_rwsem(&brw->rw_sem, name, rwsem_key); - atomic_set(&brw->write_ctr, 0); - atomic_set(&brw->slow_read_ctr, 0); - init_waitqueue_head(&brw->write_waitq); - return 0; -} - -void percpu_free_rwsem(struct percpu_rw_semaphore *brw) -{ - free_percpu(brw->fast_read_ctr); - brw->fast_read_ctr = NULL; /* catch use after free bugs */ -} - -/* - * This is the fast-path for down_read/up_read, it only needs to ensure - * there is no pending writer (atomic_read(write_ctr) == 0) and inc/dec the - * fast per-cpu counter. The writer uses synchronize_sched_expedited() to - * serialize with the preempt-disabled section below. - * - * The nontrivial part is that we should guarantee acquire/release semantics - * in case when - * - * R_W: down_write() comes after up_read(), the writer should see all - * changes done by the reader - * or - * W_R: down_read() comes after up_write(), the reader should see all - * changes done by the writer - * - * If this helper fails the callers rely on the normal rw_semaphore and - * atomic_dec_and_test(), so in this case we have the necessary barriers. - * - * But if it succeeds we do not have any barriers, atomic_read(write_ctr) or - * __this_cpu_add() below can be reordered with any LOAD/STORE done by the - * reader inside the critical section. See the comments in down_write and - * up_write below. - */ -static bool update_fast_ctr(struct percpu_rw_semaphore *brw, unsigned int val) -{ - bool success = false; - - preempt_disable(); - if (likely(!atomic_read(&brw->write_ctr))) { - __this_cpu_add(*brw->fast_read_ctr, val); - success = true; - } - preempt_enable(); - - return success; -} - -/* - * Like the normal down_read() this is not recursive, the writer can - * come after the first percpu_down_read() and create the deadlock. - * - * Note: returns with lock_is_held(brw->rw_sem) == T for lockdep, - * percpu_up_read() does rwsem_release(). This pairs with the usage - * of ->rw_sem in percpu_down/up_write(). - */ -void percpu_down_read(struct percpu_rw_semaphore *brw) -{ - might_sleep(); - if (likely(update_fast_ctr(brw, +1))) { - rwsem_acquire_read(&brw->rw_sem.dep_map, 0, 0, _RET_IP_); - return; - } - - down_read(&brw->rw_sem); - atomic_inc(&brw->slow_read_ctr); - /* avoid up_read()->rwsem_release() */ - __up_read(&brw->rw_sem); -} - -void percpu_up_read(struct percpu_rw_semaphore *brw) -{ - rwsem_release(&brw->rw_sem.dep_map, 1, _RET_IP_); - - if (likely(update_fast_ctr(brw, -1))) - return; - - /* false-positive is possible but harmless */ - if (atomic_dec_and_test(&brw->slow_read_ctr)) - wake_up_all(&brw->write_waitq); -} - -static int clear_fast_ctr(struct percpu_rw_semaphore *brw) -{ - unsigned int sum = 0; - int cpu; - - for_each_possible_cpu(cpu) { - sum += per_cpu(*brw->fast_read_ctr, cpu); - per_cpu(*brw->fast_read_ctr, cpu) = 0; - } - - return sum; -} - -/* - * A writer increments ->write_ctr to force the readers to switch to the - * slow mode, note the atomic_read() check in update_fast_ctr(). - * - * After that the readers can only inc/dec the slow ->slow_read_ctr counter, - * ->fast_read_ctr is stable. Once the writer moves its sum into the slow - * counter it represents the number of active readers. - * - * Finally the writer takes ->rw_sem for writing and blocks the new readers, - * then waits until the slow counter becomes zero. - */ -void percpu_down_write(struct percpu_rw_semaphore *brw) -{ - /* tell update_fast_ctr() there is a pending writer */ - atomic_inc(&brw->write_ctr); - /* - * 1. Ensures that write_ctr != 0 is visible to any down_read/up_read - * so that update_fast_ctr() can't succeed. - * - * 2. Ensures we see the result of every previous this_cpu_add() in - * update_fast_ctr(). - * - * 3. Ensures that if any reader has exited its critical section via - * fast-path, it executes a full memory barrier before we return. - * See R_W case in the comment above update_fast_ctr(). - */ - synchronize_sched_expedited(); - - /* exclude other writers, and block the new readers completely */ - down_write(&brw->rw_sem); - - /* nobody can use fast_read_ctr, move its sum into slow_read_ctr */ - atomic_add(clear_fast_ctr(brw), &brw->slow_read_ctr); - - /* wait for all readers to complete their percpu_up_read() */ - wait_event(brw->write_waitq, !atomic_read(&brw->slow_read_ctr)); -} - -void percpu_up_write(struct percpu_rw_semaphore *brw) -{ - /* release the lock, but the readers can't use the fast-path */ - up_write(&brw->rw_sem); - /* - * Insert the barrier before the next fast-path in down_read, - * see W_R case in the comment above update_fast_ctr(). - */ - synchronize_sched_expedited(); - /* the last writer unblocks update_fast_ctr() */ - atomic_dec(&brw->write_ctr); -} diff --git a/lib/rwsem-spinlock.c b/lib/rwsem-spinlock.c deleted file mode 100644 index 9be8a9144978..000000000000 --- a/lib/rwsem-spinlock.c +++ /dev/null @@ -1,296 +0,0 @@ -/* 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.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->activity != 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->activity = 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; - 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->activity += 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 - */ -void __sched __down_read(struct rw_semaphore *sem) -{ - struct rwsem_waiter waiter; - struct task_struct *tsk; - unsigned long flags; - - raw_spin_lock_irqsave(&sem->wait_lock, flags); - - if (sem->activity >= 0 && list_empty(&sem->wait_list)) { - /* granted */ - sem->activity++; - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - goto out; - } - - tsk = current; - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - - /* set up my own style of waitqueue */ - waiter.task = tsk; - waiter.type = RWSEM_WAITING_FOR_READ; - get_task_struct(tsk); - - list_add_tail(&waiter.list, &sem->wait_list); - - /* we don't need to touch the semaphore struct anymore */ - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - - /* wait to be given the lock */ - for (;;) { - if (!waiter.task) - break; - schedule(); - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - } - - tsk->state = TASK_RUNNING; - out: - ; -} - -/* - * 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->activity >= 0 && list_empty(&sem->wait_list)) { - /* granted */ - sem->activity++; - ret = 1; - } - - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - - return ret; -} - -/* - * get a write lock on the semaphore - */ -void __sched __down_write_nested(struct rw_semaphore *sem, int subclass) -{ - struct rwsem_waiter waiter; - struct task_struct *tsk; - unsigned long flags; - - raw_spin_lock_irqsave(&sem->wait_lock, flags); - - /* set up my own style of waitqueue */ - tsk = current; - waiter.task = tsk; - 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->activity == 0) - break; - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - schedule(); - raw_spin_lock_irqsave(&sem->wait_lock, flags); - } - /* got the lock */ - sem->activity = -1; - list_del(&waiter.list); - - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); -} - -void __sched __down_write(struct rw_semaphore *sem) -{ - __down_write_nested(sem, 0); -} - -/* - * 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->activity == 0) { - /* got the lock */ - sem->activity = -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->activity == 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->activity = 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->activity = 1; - if (!list_empty(&sem->wait_list)) - sem = __rwsem_do_wake(sem, 0); - - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); -} - diff --git a/lib/rwsem.c b/lib/rwsem.c deleted file mode 100644 index 19c5fa95e0b4..000000000000 --- a/lib/rwsem.c +++ /dev/null @@ -1,293 +0,0 @@ -/* rwsem.c: R/W semaphores: contention handling functions - * - * Written by David Howells (dhowells@redhat.com). - * Derived from arch/i386/kernel/semaphore.c - * - * Writer lock-stealing by Alex Shi <alex.shi@intel.com> - * and Michel Lespinasse <walken@google.com> - */ -#include <linux/rwsem.h> -#include <linux/sched.h> -#include <linux/init.h> -#include <linux/export.h> - -/* - * Initialize an rwsem: - */ -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 = RWSEM_UNLOCKED_VALUE; - raw_spin_lock_init(&sem->wait_lock); - INIT_LIST_HEAD(&sem->wait_list); -} - -EXPORT_SYMBOL(__init_rwsem); - -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; -}; - -enum rwsem_wake_type { - RWSEM_WAKE_ANY, /* Wake whatever's at head of wait list */ - RWSEM_WAKE_READERS, /* Wake readers only */ - RWSEM_WAKE_READ_OWNED /* Waker thread holds the read lock */ -}; - -/* - * handle the lock release when processes blocked on it that can now run - * - if we come here from up_xxxx(), then: - * - the 'active part' of count (&0x0000ffff) reached 0 (but may have changed) - * - the 'waiting part' of count (&0xffff0000) is -ve (and will still be so) - * - there must be someone on the queue - * - 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 downgrading is false - */ -static struct rw_semaphore * -__rwsem_do_wake(struct rw_semaphore *sem, enum rwsem_wake_type wake_type) -{ - struct rwsem_waiter *waiter; - struct task_struct *tsk; - struct list_head *next; - long oldcount, woken, loop, adjustment; - - waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list); - if (waiter->type == RWSEM_WAITING_FOR_WRITE) { - if (wake_type == RWSEM_WAKE_ANY) - /* Wake writer at the front of the queue, but do not - * grant it the lock yet as we want other writers - * to be able to steal it. Readers, on the other hand, - * will block as they will notice the queued writer. - */ - wake_up_process(waiter->task); - goto out; - } - - /* Writers might steal the lock before we grant it to the next reader. - * We prefer to do the first reader grant before counting readers - * so we can bail out early if a writer stole the lock. - */ - adjustment = 0; - if (wake_type != RWSEM_WAKE_READ_OWNED) { - adjustment = RWSEM_ACTIVE_READ_BIAS; - try_reader_grant: - oldcount = rwsem_atomic_update(adjustment, sem) - adjustment; - if (unlikely(oldcount < RWSEM_WAITING_BIAS)) { - /* A writer stole the lock. Undo our reader grant. */ - if (rwsem_atomic_update(-adjustment, sem) & - RWSEM_ACTIVE_MASK) - goto out; - /* Last active locker left. Retry waking readers. */ - goto try_reader_grant; - } - } - - /* Grant an infinite number of read locks to the readers at the front - * of the queue. Note we increment the 'active part' of the count by - * the number of readers before waking any processes up. - */ - woken = 0; - do { - woken++; - - if (waiter->list.next == &sem->wait_list) - break; - - waiter = list_entry(waiter->list.next, - struct rwsem_waiter, list); - - } while (waiter->type != RWSEM_WAITING_FOR_WRITE); - - adjustment = woken * RWSEM_ACTIVE_READ_BIAS - adjustment; - if (waiter->type != RWSEM_WAITING_FOR_WRITE) - /* hit end of list above */ - adjustment -= RWSEM_WAITING_BIAS; - - if (adjustment) - rwsem_atomic_add(adjustment, sem); - - next = sem->wait_list.next; - loop = woken; - do { - waiter = list_entry(next, struct rwsem_waiter, list); - next = waiter->list.next; - tsk = waiter->task; - smp_mb(); - waiter->task = NULL; - wake_up_process(tsk); - put_task_struct(tsk); - } while (--loop); - - sem->wait_list.next = next; - next->prev = &sem->wait_list; - - out: - return sem; -} - -/* - * wait for the read lock to be granted - */ -struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem) -{ - long count, adjustment = -RWSEM_ACTIVE_READ_BIAS; - struct rwsem_waiter waiter; - struct task_struct *tsk = current; - - /* set up my own style of waitqueue */ - waiter.task = tsk; - waiter.type = RWSEM_WAITING_FOR_READ; - get_task_struct(tsk); - - raw_spin_lock_irq(&sem->wait_lock); - if (list_empty(&sem->wait_list)) - 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 = rwsem_atomic_update(adjustment, sem); - - /* 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)) - sem = __rwsem_do_wake(sem, RWSEM_WAKE_ANY); - - raw_spin_unlock_irq(&sem->wait_lock); - - /* wait to be given the lock */ - while (true) { - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - if (!waiter.task) - break; - schedule(); - } - - tsk->state = TASK_RUNNING; - - return sem; -} - -/* - * wait until we successfully acquire the write lock - */ -struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem) -{ - long count, adjustment = -RWSEM_ACTIVE_WRITE_BIAS; - struct rwsem_waiter waiter; - struct task_struct *tsk = current; - - /* set up my own style of waitqueue */ - waiter.task = tsk; - waiter.type = RWSEM_WAITING_FOR_WRITE; - - raw_spin_lock_irq(&sem->wait_lock); - if (list_empty(&sem->wait_list)) - 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 = rwsem_atomic_update(adjustment, sem); - - /* If there were already threads queued before us and there are no - * active writers, the lock must be read owned; so we try to wake - * any read locks that were queued ahead of us. */ - if (count > RWSEM_WAITING_BIAS && - adjustment == -RWSEM_ACTIVE_WRITE_BIAS) - sem = __rwsem_do_wake(sem, RWSEM_WAKE_READERS); - - /* wait until we successfully acquire the lock */ - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - while (true) { - if (!(count & RWSEM_ACTIVE_MASK)) { - /* Try acquiring the write lock. */ - count = RWSEM_ACTIVE_WRITE_BIAS; - if (!list_is_singular(&sem->wait_list)) - count += RWSEM_WAITING_BIAS; - - if (sem->count == RWSEM_WAITING_BIAS && - cmpxchg(&sem->count, RWSEM_WAITING_BIAS, count) == - RWSEM_WAITING_BIAS) - break; - } - - raw_spin_unlock_irq(&sem->wait_lock); - - /* Block until there are no active lockers. */ - do { - schedule(); - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - } while ((count = sem->count) & RWSEM_ACTIVE_MASK); - - raw_spin_lock_irq(&sem->wait_lock); - } - - list_del(&waiter.list); - raw_spin_unlock_irq(&sem->wait_lock); - tsk->state = TASK_RUNNING; - - return sem; -} - -/* - * handle waking up a waiter on the semaphore - * - up_read/up_write has decremented the active part of count if we come here - */ -struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem) -{ - unsigned long flags; - - raw_spin_lock_irqsave(&sem->wait_lock, flags); - - /* do nothing if list empty */ - if (!list_empty(&sem->wait_list)) - sem = __rwsem_do_wake(sem, RWSEM_WAKE_ANY); - - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - - return sem; -} - -/* - * downgrade a write lock into a read lock - * - caller incremented waiting part of count and discovered it still negative - * - just wake up any readers at the front of the queue - */ -struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem) -{ - unsigned long flags; - - raw_spin_lock_irqsave(&sem->wait_lock, flags); - - /* do nothing if list empty */ - if (!list_empty(&sem->wait_list)) - sem = __rwsem_do_wake(sem, RWSEM_WAKE_READ_OWNED); - - raw_spin_unlock_irqrestore(&sem->wait_lock, flags); - - return sem; -} - -EXPORT_SYMBOL(rwsem_down_read_failed); -EXPORT_SYMBOL(rwsem_down_write_failed); -EXPORT_SYMBOL(rwsem_wake); -EXPORT_SYMBOL(rwsem_downgrade_wake); diff --git a/lib/spinlock_debug.c b/lib/spinlock_debug.c deleted file mode 100644 index 0374a596cffa..000000000000 --- a/lib/spinlock_debug.c +++ /dev/null @@ -1,302 +0,0 @@ -/* - * 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 <linux/spinlock.h> -#include <linux/nmi.h> -#include <linux/interrupt.h> -#include <linux/debug_locks.h> -#include <linux/delay.h> -#include <linux/export.h> - -void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name, - struct lock_class_key *key) -{ -#ifdef CONFIG_DEBUG_LOCK_ALLOC - /* - * Make sure we are not reinitializing a held lock: - */ - debug_check_no_locks_freed((void *)lock, sizeof(*lock)); - lockdep_init_map(&lock->dep_map, name, key, 0); -#endif - lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; - lock->magic = SPINLOCK_MAGIC; - lock->owner = SPINLOCK_OWNER_INIT; - lock->owner_cpu = -1; -} - -EXPORT_SYMBOL(__raw_spin_lock_init); - -void __rwlock_init(rwlock_t *lock, const char *name, - struct lock_class_key *key) -{ -#ifdef CONFIG_DEBUG_LOCK_ALLOC - /* - * Make sure we are not reinitializing a held lock: - */ - debug_check_no_locks_freed((void *)lock, sizeof(*lock)); - lockdep_init_map(&lock->dep_map, name, key, 0); -#endif - lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED; - lock->magic = RWLOCK_MAGIC; - lock->owner = SPINLOCK_OWNER_INIT; - lock->owner_cpu = -1; -} - -EXPORT_SYMBOL(__rwlock_init); - -static void spin_dump(raw_spinlock_t *lock, const char *msg) -{ - struct task_struct *owner = NULL; - - if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT) - owner = lock->owner; - printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n", - msg, raw_smp_processor_id(), - current->comm, task_pid_nr(current)); - printk(KERN_EMERG " lock: %pS, .magic: %08x, .owner: %s/%d, " - ".owner_cpu: %d\n", - lock, lock->magic, - owner ? owner->comm : "<none>", - owner ? task_pid_nr(owner) : -1, - lock->owner_cpu); - dump_stack(); -} - -static void spin_bug(raw_spinlock_t *lock, const char *msg) -{ - if (!debug_locks_off()) - return; - - spin_dump(lock, msg); -} - -#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg) - -static inline void -debug_spin_lock_before(raw_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(raw_spinlock_t *lock) -{ - lock->owner_cpu = raw_smp_processor_id(); - lock->owner = current; -} - -static inline void debug_spin_unlock(raw_spinlock_t *lock) -{ - SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic"); - SPIN_BUG_ON(!raw_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(raw_spinlock_t *lock) -{ - u64 i; - u64 loops = loops_per_jiffy * HZ; - - for (i = 0; i < loops; i++) { - if (arch_spin_trylock(&lock->raw_lock)) - return; - __delay(1); - } - /* lockup suspected: */ - spin_dump(lock, "lockup suspected"); -#ifdef CONFIG_SMP - trigger_all_cpu_backtrace(); -#endif - - /* - * The trylock above was causing a livelock. Give the lower level arch - * specific lock code a chance to acquire the lock. We have already - * printed a warning/backtrace at this point. The non-debug arch - * specific code might actually succeed in acquiring the lock. If it is - * not successful, the end-result is the same - there is no forward - * progress. - */ - arch_spin_lock(&lock->raw_lock); -} - -void do_raw_spin_lock(raw_spinlock_t *lock) -{ - debug_spin_lock_before(lock); - if (unlikely(!arch_spin_trylock(&lock->raw_lock))) - __spin_lock_debug(lock); - debug_spin_lock_after(lock); -} - -int do_raw_spin_trylock(raw_spinlock_t *lock) -{ - int ret = arch_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 do_raw_spin_unlock(raw_spinlock_t *lock) -{ - debug_spin_unlock(lock); - arch_spin_unlock(&lock->raw_lock); -} - -static void rwlock_bug(rwlock_t *lock, const char *msg) -{ - if (!debug_locks_off()) - return; - - printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n", - msg, raw_smp_processor_id(), current->comm, - task_pid_nr(current), lock); - dump_stack(); -} - -#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg) - -#if 0 /* __write_lock_debug() can lock up - maybe this can too? */ -static void __read_lock_debug(rwlock_t *lock) -{ - u64 i; - u64 loops = loops_per_jiffy * HZ; - int print_once = 1; - - for (;;) { - for (i = 0; i < loops; i++) { - if (arch_read_trylock(&lock->raw_lock)) - return; - __delay(1); - } - /* lockup suspected: */ - if (print_once) { - print_once = 0; - printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, " - "%s/%d, %p\n", - raw_smp_processor_id(), current->comm, - current->pid, lock); - dump_stack(); - } - } -} -#endif - -void do_raw_read_lock(rwlock_t *lock) -{ - RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); - arch_read_lock(&lock->raw_lock); -} - -int do_raw_read_trylock(rwlock_t *lock) -{ - int ret = arch_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 do_raw_read_unlock(rwlock_t *lock) -{ - RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); - arch_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; -} - -#if 0 /* This can cause lockups */ -static void __write_lock_debug(rwlock_t *lock) -{ - u64 i; - u64 loops = loops_per_jiffy * HZ; - int print_once = 1; - - for (;;) { - for (i = 0; i < loops; i++) { - if (arch_write_trylock(&lock->raw_lock)) - return; - __delay(1); - } - /* lockup suspected: */ - if (print_once) { - print_once = 0; - printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, " - "%s/%d, %p\n", - raw_smp_processor_id(), current->comm, - current->pid, lock); - dump_stack(); - } - } -} -#endif - -void do_raw_write_lock(rwlock_t *lock) -{ - debug_write_lock_before(lock); - arch_write_lock(&lock->raw_lock); - debug_write_lock_after(lock); -} - -int do_raw_write_trylock(rwlock_t *lock) -{ - int ret = arch_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 do_raw_write_unlock(rwlock_t *lock) -{ - debug_write_unlock(lock); - arch_write_unlock(&lock->raw_lock); -} |