diff options
| -rw-r--r-- | kernel/semaphore.c | 64 |
1 files changed, 34 insertions, 30 deletions
diff --git a/kernel/semaphore.c b/kernel/semaphore.c index 5e41217..5c2942e 100644 --- a/kernel/semaphore.c +++ b/kernel/semaphore.c @@ -54,9 +54,10 @@ void down(struct semaphore *sem) unsigned long flags; spin_lock_irqsave(&sem->lock, flags); - if (unlikely(!sem->count)) + if (likely(sem->count > 0)) + sem->count--; + else __down(sem); - sem->count--; spin_unlock_irqrestore(&sem->lock, flags); } EXPORT_SYMBOL(down); @@ -76,10 +77,10 @@ int down_interruptible(struct semaphore *sem) int result = 0; spin_lock_irqsave(&sem->lock, flags); - if (unlikely(!sem->count)) - result = __down_interruptible(sem); - if (!result) + if (likely(sem->count > 0)) sem->count--; + else + result = __down_interruptible(sem); spin_unlock_irqrestore(&sem->lock, flags); return result; @@ -102,10 +103,10 @@ int down_killable(struct semaphore *sem) int result = 0; spin_lock_irqsave(&sem->lock, flags); - if (unlikely(!sem->count)) - result = __down_killable(sem); - if (!result) + if (likely(sem->count > 0)) sem->count--; + else + result = __down_killable(sem); spin_unlock_irqrestore(&sem->lock, flags); return result; @@ -156,10 +157,10 @@ int down_timeout(struct semaphore *sem, long jiffies) int result = 0; spin_lock_irqsave(&sem->lock, flags); - if (unlikely(!sem->count)) - result = __down_timeout(sem, jiffies); - if (!result) + if (likely(sem->count > 0)) sem->count--; + else + result = __down_timeout(sem, jiffies); spin_unlock_irqrestore(&sem->lock, flags); return result; @@ -178,8 +179,9 @@ void up(struct semaphore *sem) unsigned long flags; spin_lock_irqsave(&sem->lock, flags); - sem->count++; - if (unlikely(!list_empty(&sem->wait_list))) + if (likely(list_empty(&sem->wait_list))) + sem->count++; + else __up(sem); spin_unlock_irqrestore(&sem->lock, flags); } @@ -190,6 +192,7 @@ EXPORT_SYMBOL(up); struct semaphore_waiter { struct list_head list; struct task_struct *task; + int up; }; /* @@ -202,34 +205,33 @@ static inline int __sched __down_common(struct semaphore *sem, long state, { struct task_struct *task = current; struct semaphore_waiter waiter; - int ret = 0; - waiter.task = task; list_add_tail(&waiter.list, &sem->wait_list); + waiter.task = task; + waiter.up = 0; for (;;) { - if (state == TASK_INTERRUPTIBLE && signal_pending(task)) { - ret = -EINTR; - break; - } - if (state == TASK_KILLABLE && fatal_signal_pending(task)) { - ret = -EINTR; - break; - } - if (timeout <= 0) { - ret = -ETIME; - break; - } + if (state == TASK_INTERRUPTIBLE && signal_pending(task)) + goto interrupted; + if (state == TASK_KILLABLE && fatal_signal_pending(task)) + goto interrupted; + if (timeout <= 0) + goto timed_out; __set_task_state(task, state); spin_unlock_irq(&sem->lock); timeout = schedule_timeout(timeout); spin_lock_irq(&sem->lock); - if (sem->count > 0) - break; + if (waiter.up) + return 0; } + timed_out: + list_del(&waiter.list); + return -ETIME; + + interrupted: list_del(&waiter.list); - return ret; + return -EINTR; } static noinline void __sched __down(struct semaphore *sem) @@ -256,5 +258,7 @@ static noinline void __sched __up(struct semaphore *sem) { struct semaphore_waiter *waiter = list_first_entry(&sem->wait_list, struct semaphore_waiter, list); + list_del(&waiter->list); + waiter->up = 1; wake_up_process(waiter->task); } |
