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authorMatthew Wilcox <matthew@wil.cx>2008-03-07 21:55:58 -0500
committerMatthew Wilcox <willy@linux.intel.com>2008-04-17 10:42:34 -0400
commit64ac24e738823161693bf791f87adc802cf529ff (patch)
tree19c0b0cf314d4394ca580c05b86cdf874ce0a167 /include/asm-sh
parente48b3deee475134585eed03e7afebe4bf9e0dba9 (diff)
downloadop-kernel-dev-64ac24e738823161693bf791f87adc802cf529ff.zip
op-kernel-dev-64ac24e738823161693bf791f87adc802cf529ff.tar.gz
Generic semaphore implementation
Semaphores are no longer performance-critical, so a generic C implementation is better for maintainability, debuggability and extensibility. Thanks to Peter Zijlstra for fixing the lockdep warning. Thanks to Harvey Harrison for pointing out that the unlikely() was unnecessary. Signed-off-by: Matthew Wilcox <willy@linux.intel.com> Acked-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/asm-sh')
-rw-r--r--include/asm-sh/semaphore-helper.h89
-rw-r--r--include/asm-sh/semaphore.h116
2 files changed, 1 insertions, 204 deletions
diff --git a/include/asm-sh/semaphore-helper.h b/include/asm-sh/semaphore-helper.h
deleted file mode 100644
index bd8230c..0000000
--- a/include/asm-sh/semaphore-helper.h
+++ /dev/null
@@ -1,89 +0,0 @@
-#ifndef __ASM_SH_SEMAPHORE_HELPER_H
-#define __ASM_SH_SEMAPHORE_HELPER_H
-
-/*
- * SMP- and interrupt-safe semaphores helper functions.
- *
- * (C) Copyright 1996 Linus Torvalds
- * (C) Copyright 1999 Andrea Arcangeli
- */
-
-/*
- * These two _must_ execute atomically wrt each other.
- *
- * This is trivially done with load_locked/store_cond,
- * which we have. Let the rest of the losers suck eggs.
- */
-static __inline__ void wake_one_more(struct semaphore * sem)
-{
- atomic_inc((atomic_t *)&sem->sleepers);
-}
-
-static __inline__ int waking_non_zero(struct semaphore *sem)
-{
- unsigned long flags;
- int ret = 0;
-
- spin_lock_irqsave(&semaphore_wake_lock, flags);
- if (sem->sleepers > 0) {
- sem->sleepers--;
- ret = 1;
- }
- spin_unlock_irqrestore(&semaphore_wake_lock, flags);
- return ret;
-}
-
-/*
- * waking_non_zero_interruptible:
- * 1 got the lock
- * 0 go to sleep
- * -EINTR interrupted
- *
- * We must undo the sem->count down_interruptible() increment while we are
- * protected by the spinlock in order to make atomic this atomic_inc() with the
- * atomic_read() in wake_one_more(), otherwise we can race. -arca
- */
-static __inline__ int waking_non_zero_interruptible(struct semaphore *sem,
- struct task_struct *tsk)
-{
- unsigned long flags;
- int ret = 0;
-
- spin_lock_irqsave(&semaphore_wake_lock, flags);
- if (sem->sleepers > 0) {
- sem->sleepers--;
- ret = 1;
- } else if (signal_pending(tsk)) {
- atomic_inc(&sem->count);
- ret = -EINTR;
- }
- spin_unlock_irqrestore(&semaphore_wake_lock, flags);
- return ret;
-}
-
-/*
- * waking_non_zero_trylock:
- * 1 failed to lock
- * 0 got the lock
- *
- * We must undo the sem->count down_trylock() increment while we are
- * protected by the spinlock in order to make atomic this atomic_inc() with the
- * atomic_read() in wake_one_more(), otherwise we can race. -arca
- */
-static __inline__ int waking_non_zero_trylock(struct semaphore *sem)
-{
- unsigned long flags;
- int ret = 1;
-
- spin_lock_irqsave(&semaphore_wake_lock, flags);
- if (sem->sleepers <= 0)
- atomic_inc(&sem->count);
- else {
- sem->sleepers--;
- ret = 0;
- }
- spin_unlock_irqrestore(&semaphore_wake_lock, flags);
- return ret;
-}
-
-#endif /* __ASM_SH_SEMAPHORE_HELPER_H */
diff --git a/include/asm-sh/semaphore.h b/include/asm-sh/semaphore.h
index 9e5a37c..d9b2034 100644
--- a/include/asm-sh/semaphore.h
+++ b/include/asm-sh/semaphore.h
@@ -1,115 +1 @@
-#ifndef __ASM_SH_SEMAPHORE_H
-#define __ASM_SH_SEMAPHORE_H
-
-#include <linux/linkage.h>
-
-#ifdef __KERNEL__
-/*
- * SMP- and interrupt-safe semaphores.
- *
- * (C) Copyright 1996 Linus Torvalds
- *
- * SuperH verison by Niibe Yutaka
- * (Currently no asm implementation but generic C code...)
- */
-
-#include <linux/spinlock.h>
-#include <linux/rwsem.h>
-#include <linux/wait.h>
-
-#include <asm/system.h>
-#include <asm/atomic.h>
-
-struct semaphore {
- atomic_t count;
- int sleepers;
- wait_queue_head_t wait;
-};
-
-#define __SEMAPHORE_INITIALIZER(name, n) \
-{ \
- .count = ATOMIC_INIT(n), \
- .sleepers = 0, \
- .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
-}
-
-#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
- struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
-
-#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
-
-static inline void sema_init (struct semaphore *sem, int val)
-{
-/*
- * *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
- *
- * i'd rather use the more flexible initialization above, but sadly
- * GCC 2.7.2.3 emits a bogus warning. EGCS doesn't. Oh well.
- */
- atomic_set(&sem->count, val);
- sem->sleepers = 0;
- init_waitqueue_head(&sem->wait);
-}
-
-static inline void init_MUTEX (struct semaphore *sem)
-{
- sema_init(sem, 1);
-}
-
-static inline void init_MUTEX_LOCKED (struct semaphore *sem)
-{
- sema_init(sem, 0);
-}
-
-#if 0
-asmlinkage void __down_failed(void /* special register calling convention */);
-asmlinkage int __down_failed_interruptible(void /* params in registers */);
-asmlinkage int __down_failed_trylock(void /* params in registers */);
-asmlinkage void __up_wakeup(void /* special register calling convention */);
-#endif
-
-asmlinkage void __down(struct semaphore * sem);
-asmlinkage int __down_interruptible(struct semaphore * sem);
-asmlinkage int __down_trylock(struct semaphore * sem);
-asmlinkage void __up(struct semaphore * sem);
-
-extern spinlock_t semaphore_wake_lock;
-
-static inline void down(struct semaphore * sem)
-{
- might_sleep();
- if (atomic_dec_return(&sem->count) < 0)
- __down(sem);
-}
-
-static inline int down_interruptible(struct semaphore * sem)
-{
- int ret = 0;
-
- might_sleep();
- if (atomic_dec_return(&sem->count) < 0)
- ret = __down_interruptible(sem);
- return ret;
-}
-
-static inline int down_trylock(struct semaphore * sem)
-{
- int ret = 0;
-
- if (atomic_dec_return(&sem->count) < 0)
- ret = __down_trylock(sem);
- return ret;
-}
-
-/*
- * Note! This is subtle. We jump to wake people up only if
- * the semaphore was negative (== somebody was waiting on it).
- */
-static inline void up(struct semaphore * sem)
-{
- if (atomic_inc_return(&sem->count) <= 0)
- __up(sem);
-}
-
-#endif
-#endif /* __ASM_SH_SEMAPHORE_H */
+#include <linux/semaphore.h>
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