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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 <[email protected]> Acked-by: Ingo Molnar <[email protected]>
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Matthew Wilcox
Matthew Wilcox
parent
e48b3deee4
commit
64ac24e738
113 changed files with 314 additions and 7679 deletions
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#ifndef _H8300_SEMAPHORE_HELPER_H
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#define _H8300_SEMAPHORE_HELPER_H
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/*
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* SMP- and interrupt-safe semaphores helper functions.
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*
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* (C) Copyright 1996 Linus Torvalds
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*
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* based on
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* m68k version by Andreas Schwab
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*/
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#include <linux/errno.h>
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/*
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* These two _must_ execute atomically wrt each other.
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*/
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static inline void wake_one_more(struct semaphore * sem)
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{
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atomic_inc((atomic_t *)&sem->sleepers);
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}
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static inline int waking_non_zero(struct semaphore *sem)
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{
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int ret;
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unsigned long flags;
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spin_lock_irqsave(&semaphore_wake_lock, flags);
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ret = 0;
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if (sem->sleepers > 0) {
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sem->sleepers--;
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ret = 1;
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}
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spin_unlock_irqrestore(&semaphore_wake_lock, flags);
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return ret;
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}
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/*
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* waking_non_zero_interruptible:
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* 1 got the lock
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* 0 go to sleep
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* -EINTR interrupted
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*/
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static inline int waking_non_zero_interruptible(struct semaphore *sem,
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struct task_struct *tsk)
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{
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int ret;
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unsigned long flags;
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spin_lock_irqsave(&semaphore_wake_lock, flags);
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ret = 0;
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if (sem->sleepers > 0) {
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sem->sleepers--;
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ret = 1;
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} else if (signal_pending(tsk)) {
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atomic_inc(&sem->count);
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ret = -EINTR;
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}
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spin_unlock_irqrestore(&semaphore_wake_lock, flags);
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return ret;
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}
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/*
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* waking_non_zero_trylock:
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* 1 failed to lock
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* 0 got the lock
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*/
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static inline int waking_non_zero_trylock(struct semaphore *sem)
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{
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int ret;
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unsigned long flags;
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spin_lock_irqsave(&semaphore_wake_lock, flags);
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ret = 1;
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if (sem->sleepers <= 0)
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atomic_inc(&sem->count);
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else {
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sem->sleepers--;
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ret = 0;
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}
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spin_unlock_irqrestore(&semaphore_wake_lock, flags);
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return ret;
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}
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#endif
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@ -1,190 +1 @@
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#ifndef _H8300_SEMAPHORE_H
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#define _H8300_SEMAPHORE_H
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#define RW_LOCK_BIAS 0x01000000
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#ifndef __ASSEMBLY__
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#include <linux/linkage.h>
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#include <linux/wait.h>
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#include <linux/spinlock.h>
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#include <linux/rwsem.h>
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#include <asm/system.h>
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#include <asm/atomic.h>
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/*
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* Interrupt-safe semaphores..
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*
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* (C) Copyright 1996 Linus Torvalds
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*
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* H8/300 version by Yoshinori Sato
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*/
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struct semaphore {
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atomic_t count;
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int sleepers;
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wait_queue_head_t wait;
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};
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#define __SEMAPHORE_INITIALIZER(name, n) \
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{ \
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.count = ATOMIC_INIT(n), \
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.sleepers = 0, \
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.wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
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}
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#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
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struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
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#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
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static inline void sema_init (struct semaphore *sem, int val)
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{
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*sem = (struct semaphore)__SEMAPHORE_INITIALIZER(*sem, val);
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}
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static inline void init_MUTEX (struct semaphore *sem)
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{
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sema_init(sem, 1);
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}
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static inline void init_MUTEX_LOCKED (struct semaphore *sem)
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{
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sema_init(sem, 0);
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}
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asmlinkage void __down_failed(void /* special register calling convention */);
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asmlinkage int __down_failed_interruptible(void /* params in registers */);
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asmlinkage int __down_failed_trylock(void /* params in registers */);
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asmlinkage void __up_wakeup(void /* special register calling convention */);
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asmlinkage void __down(struct semaphore * sem);
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asmlinkage int __down_interruptible(struct semaphore * sem);
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asmlinkage int __down_trylock(struct semaphore * sem);
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asmlinkage void __up(struct semaphore * sem);
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extern spinlock_t semaphore_wake_lock;
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/*
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* This is ugly, but we want the default case to fall through.
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* "down_failed" is a special asm handler that calls the C
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* routine that actually waits. See arch/m68k/lib/semaphore.S
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*/
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static inline void down(struct semaphore * sem)
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{
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register atomic_t *count asm("er0");
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might_sleep();
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count = &(sem->count);
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__asm__ __volatile__(
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"stc ccr,r3l\n\t"
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"orc #0x80,ccr\n\t"
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"mov.l %2, er1\n\t"
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"dec.l #1,er1\n\t"
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"mov.l er1,%0\n\t"
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"bpl 1f\n\t"
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"ldc r3l,ccr\n\t"
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"mov.l %1,er0\n\t"
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"jsr @___down\n\t"
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"bra 2f\n"
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"1:\n\t"
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"ldc r3l,ccr\n"
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"2:"
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: "=m"(*count)
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: "g"(sem),"m"(*count)
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: "cc", "er1", "er2", "er3");
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}
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static inline int down_interruptible(struct semaphore * sem)
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{
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register atomic_t *count asm("er0");
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might_sleep();
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count = &(sem->count);
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__asm__ __volatile__(
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"stc ccr,r1l\n\t"
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"orc #0x80,ccr\n\t"
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"mov.l %3, er2\n\t"
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"dec.l #1,er2\n\t"
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"mov.l er2,%1\n\t"
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"bpl 1f\n\t"
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"ldc r1l,ccr\n\t"
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"mov.l %2,er0\n\t"
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"jsr @___down_interruptible\n\t"
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"bra 2f\n"
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"1:\n\t"
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"ldc r1l,ccr\n\t"
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"sub.l %0,%0\n\t"
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"2:\n\t"
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: "=r" (count),"=m" (*count)
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: "g"(sem),"m"(*count)
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: "cc", "er1", "er2", "er3");
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return (int)count;
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}
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static inline int down_trylock(struct semaphore * sem)
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{
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register atomic_t *count asm("er0");
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count = &(sem->count);
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__asm__ __volatile__(
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"stc ccr,r3l\n\t"
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"orc #0x80,ccr\n\t"
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"mov.l %3,er2\n\t"
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"dec.l #1,er2\n\t"
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"mov.l er2,%0\n\t"
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"bpl 1f\n\t"
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"ldc r3l,ccr\n\t"
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"jmp @3f\n\t"
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LOCK_SECTION_START(".align 2\n\t")
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"3:\n\t"
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"mov.l %2,er0\n\t"
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"jsr @___down_trylock\n\t"
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"jmp @2f\n\t"
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LOCK_SECTION_END
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"1:\n\t"
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"ldc r3l,ccr\n\t"
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"sub.l %1,%1\n"
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"2:"
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: "=m" (*count),"=r"(count)
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: "g"(sem),"m"(*count)
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: "cc", "er1","er2", "er3");
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return (int)count;
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}
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/*
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* Note! This is subtle. We jump to wake people up only if
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* the semaphore was negative (== somebody was waiting on it).
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* The default case (no contention) will result in NO
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* jumps for both down() and up().
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*/
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static inline void up(struct semaphore * sem)
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{
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register atomic_t *count asm("er0");
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count = &(sem->count);
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__asm__ __volatile__(
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"stc ccr,r3l\n\t"
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"orc #0x80,ccr\n\t"
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"mov.l %2,er1\n\t"
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"inc.l #1,er1\n\t"
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"mov.l er1,%0\n\t"
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"ldc r3l,ccr\n\t"
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"sub.l er2,er2\n\t"
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"cmp.l er2,er1\n\t"
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"bgt 1f\n\t"
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"mov.l %1,er0\n\t"
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"jsr @___up\n"
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"1:"
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: "=m"(*count)
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: "g"(sem),"m"(*count)
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: "cc", "er1", "er2", "er3");
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}
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#endif /* __ASSEMBLY__ */
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#endif
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#include <linux/semaphore.h>
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