semaphore: fix

[firefly-linux-kernel-4.4.55.git] / kernel / semaphore.c

diff --git a/kernel/semaphore.c b/kernel/semaphore.c
index 5c2942e768cdd44371ae305d5870abfe7428732c..5e41217239e89f3fa203f9f73e4476e0985ecd79 100644 (file)
--- 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);
 }