diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig.debug | 10 | ||||
| -rw-r--r-- | lib/Makefile | 1 | ||||
| -rw-r--r-- | lib/kernel_lock.c | 1 | ||||
| -rw-r--r-- | lib/semaphore-sleepers.c | 176 |
4 files changed, 1 insertions, 187 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index eef557dc46c..80db357b0a4 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -265,16 +265,6 @@ config DEBUG_MUTEXES This feature allows mutex semantics violations to be detected and reported. -config DEBUG_SEMAPHORE - bool "Semaphore debugging" - depends on DEBUG_KERNEL - depends on ALPHA || FRV - default n - help - If you say Y here then semaphore processing will issue lots of - verbose debugging messages. If you suspect a semaphore problem or a - kernel hacker asks for this option then say Y. Otherwise say N. - config DEBUG_LOCK_ALLOC bool "Lock debugging: detect incorrect freeing of live locks" depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT diff --git a/lib/Makefile b/lib/Makefile index 23de261a4c8..28dba90d502 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -29,7 +29,6 @@ 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-$(CONFIG_SEMAPHORE_SLEEPERS) += semaphore-sleepers.o lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.o obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o obj-$(CONFIG_LOCK_KERNEL) += kernel_lock.o diff --git a/lib/kernel_lock.c b/lib/kernel_lock.c index 812dbf00844..fbc11a336bc 100644 --- a/lib/kernel_lock.c +++ b/lib/kernel_lock.c @@ -8,6 +8,7 @@ #include <linux/smp_lock.h> #include <linux/module.h> #include <linux/kallsyms.h> +#include <asm/semaphore.h> /* * The 'big kernel semaphore' diff --git a/lib/semaphore-sleepers.c b/lib/semaphore-sleepers.c deleted file mode 100644 index 0198782cdac..00000000000 --- a/lib/semaphore-sleepers.c +++ /dev/null @@ -1,176 +0,0 @@ -/* - * i386 and x86-64 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/sched.h> -#include <linux/err.h> -#include <linux/init.h> -#include <asm/semaphore.h> - -/* - * Semaphores are implemented using a two-way counter: - * The "count" variable is decremented for each process - * that tries to acquire the semaphore, while the "sleeping" - * variable is a count of such acquires. - * - * Notably, the inline "up()" and "down()" functions can - * efficiently test if they need to do any extra work (up - * needs to do something only if count was negative before - * the increment operation. - * - * "sleeping" and the contention routine ordering is protected - * by the spinlock in the semaphore's waitqueue head. - * - * Note that these functions are only called when there is - * contention on the lock, and as such all this is the - * "non-critical" part of the whole semaphore business. The - * critical part is the inline stuff in <asm/semaphore.h> - * where we want to avoid any extra jumps and calls. - */ - -/* - * Logic: - * - only on a boundary condition do we need to care. When we go - * from a negative count to a non-negative, we wake people up. - * - when we go from a non-negative count to a negative do we - * (a) synchronize with the "sleeper" count and (b) make sure - * that we're on the wakeup list before we synchronize so that - * we cannot lose wakeup events. - */ - -void __up(struct semaphore *sem) -{ - wake_up(&sem->wait); -} - -void __sched __down(struct semaphore *sem) -{ - struct task_struct *tsk = current; - DECLARE_WAITQUEUE(wait, tsk); - unsigned long flags; - - tsk->state = TASK_UNINTERRUPTIBLE; - spin_lock_irqsave(&sem->wait.lock, flags); - add_wait_queue_exclusive_locked(&sem->wait, &wait); - - sem->sleepers++; - for (;;) { - int sleepers = sem->sleepers; - - /* - * Add "everybody else" into it. They aren't - * playing, because we own the spinlock in - * the wait_queue_head. - */ - if (!atomic_add_negative(sleepers - 1, &sem->count)) { - sem->sleepers = 0; - break; - } - sem->sleepers = 1; /* us - see -1 above */ - spin_unlock_irqrestore(&sem->wait.lock, flags); - - schedule(); - - spin_lock_irqsave(&sem->wait.lock, flags); - tsk->state = TASK_UNINTERRUPTIBLE; - } - remove_wait_queue_locked(&sem->wait, &wait); - wake_up_locked(&sem->wait); - spin_unlock_irqrestore(&sem->wait.lock, flags); - tsk->state = TASK_RUNNING; -} - -int __sched __down_interruptible(struct semaphore *sem) -{ - int retval = 0; - struct task_struct *tsk = current; - DECLARE_WAITQUEUE(wait, tsk); - unsigned long flags; - - tsk->state = TASK_INTERRUPTIBLE; - spin_lock_irqsave(&sem->wait.lock, flags); - add_wait_queue_exclusive_locked(&sem->wait, &wait); - - sem->sleepers++; - for (;;) { - int sleepers = sem->sleepers; - - /* - * With signals pending, this turns into - * the trylock failure case - we won't be - * sleeping, and we* can't get the lock as - * it has contention. Just correct the count - * and exit. - */ - if (signal_pending(current)) { - retval = -EINTR; - sem->sleepers = 0; - atomic_add(sleepers, &sem->count); - break; - } - - /* - * Add "everybody else" into it. They aren't - * playing, because we own the spinlock in - * wait_queue_head. The "-1" is because we're - * still hoping to get the semaphore. - */ - if (!atomic_add_negative(sleepers - 1, &sem->count)) { - sem->sleepers = 0; - break; - } - sem->sleepers = 1; /* us - see -1 above */ - spin_unlock_irqrestore(&sem->wait.lock, flags); - - schedule(); - - spin_lock_irqsave(&sem->wait.lock, flags); - tsk->state = TASK_INTERRUPTIBLE; - } - remove_wait_queue_locked(&sem->wait, &wait); - wake_up_locked(&sem->wait); - spin_unlock_irqrestore(&sem->wait.lock, flags); - - tsk->state = TASK_RUNNING; - return retval; -} - -/* - * Trylock failed - make sure we correct for - * having decremented the count. - * - * We could have done the trylock with a - * single "cmpxchg" without failure cases, - * but then it wouldn't work on a 386. - */ -int __down_trylock(struct semaphore *sem) -{ - int sleepers; - unsigned long flags; - - spin_lock_irqsave(&sem->wait.lock, flags); - sleepers = sem->sleepers + 1; - sem->sleepers = 0; - - /* - * Add "everybody else" and us into it. They aren't - * playing, because we own the spinlock in the - * wait_queue_head. - */ - if (!atomic_add_negative(sleepers, &sem->count)) { - wake_up_locked(&sem->wait); - } - - spin_unlock_irqrestore(&sem->wait.lock, flags); - return 1; -} |