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-rw-r--r--kernel/semaphore.c64
1 files changed, 30 insertions, 34 deletions
diff --git a/kernel/semaphore.c b/kernel/semaphore.c
index 5c2942e..5e41217 100644
--- a/kernel/semaphore.c
+++ b/kernel/semaphore.c
@@ -54,10 +54,9 @@ void down(struct semaphore *sem)
unsigned long flags;
spin_lock_irqsave(&sem->lock, flags);
- if (likely(sem->count > 0))
- sem->count--;
- else
+ if (unlikely(!sem->count))
__down(sem);
+ sem->count--;
spin_unlock_irqrestore(&sem->lock, flags);
}
EXPORT_SYMBOL(down);
@@ -77,10 +76,10 @@ int down_interruptible(struct semaphore *sem)
int result = 0;
spin_lock_irqsave(&sem->lock, flags);
- if (likely(sem->count > 0))
- sem->count--;
- else
+ if (unlikely(!sem->count))
result = __down_interruptible(sem);
+ if (!result)
+ sem->count--;
spin_unlock_irqrestore(&sem->lock, flags);
return result;
@@ -103,10 +102,10 @@ int down_killable(struct semaphore *sem)
int result = 0;
spin_lock_irqsave(&sem->lock, flags);
- if (likely(sem->count > 0))
- sem->count--;
- else
+ if (unlikely(!sem->count))
result = __down_killable(sem);
+ if (!result)
+ sem->count--;
spin_unlock_irqrestore(&sem->lock, flags);
return result;
@@ -157,10 +156,10 @@ int down_timeout(struct semaphore *sem, long jiffies)
int result = 0;
spin_lock_irqsave(&sem->lock, flags);
- if (likely(sem->count > 0))
- sem->count--;
- else
+ if (unlikely(!sem->count))
result = __down_timeout(sem, jiffies);
+ if (!result)
+ sem->count--;
spin_unlock_irqrestore(&sem->lock, flags);
return result;
@@ -179,9 +178,8 @@ void up(struct semaphore *sem)
unsigned long flags;
spin_lock_irqsave(&sem->lock, flags);
- if (likely(list_empty(&sem->wait_list)))
- sem->count++;
- else
+ sem->count++;
+ if (unlikely(!list_empty(&sem->wait_list)))
__up(sem);
spin_unlock_irqrestore(&sem->lock, flags);
}
@@ -192,7 +190,6 @@ EXPORT_SYMBOL(up);
struct semaphore_waiter {
struct list_head list;
struct task_struct *task;
- int up;
};
/*
@@ -205,33 +202,34 @@ static inline int __sched __down_common(struct semaphore *sem, long state,
{
struct task_struct *task = current;
struct semaphore_waiter waiter;
+ int ret = 0;
- list_add_tail(&waiter.list, &sem->wait_list);
waiter.task = task;
- waiter.up = 0;
+ list_add_tail(&waiter.list, &sem->wait_list);
for (;;) {
- 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;
+ 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;
+ }
__set_task_state(task, state);
spin_unlock_irq(&sem->lock);
timeout = schedule_timeout(timeout);
spin_lock_irq(&sem->lock);
- if (waiter.up)
- return 0;
+ if (sem->count > 0)
+ break;
}
- timed_out:
- list_del(&waiter.list);
- return -ETIME;
-
- interrupted:
list_del(&waiter.list);
- return -EINTR;
+ return ret;
}
static noinline void __sched __down(struct semaphore *sem)
@@ -258,7 +256,5 @@ 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);
}
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