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Diffstat (limited to 'kernel/semaphore.c')
-rw-r--r--kernel/semaphore.c64
1 files changed, 34 insertions, 30 deletions
diff --git a/kernel/semaphore.c b/kernel/semaphore.c
index 5e41217239e8..5c2942e768cd 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);
}