[PATCH] Remove global semaphore_lock for ia64, similar to i386 change for 2.5.25

arch/ia64/kernel/semaphore.c

@@ -15,8 +15,8 @@
  * test if they need to do any extra work (up needs to do something
  * only if count was negative before the increment operation.
  *
- * "sleepers" and the contention routine ordering is protected by the
- * semaphore spinlock.
+ * "sleeping" and the contention routine ordering is protected
+ * by the spinlock in the semaphore's waitqueue head.
  *
  * Note that these functions are only called when there is contention
  * on the lock, and as such all this is the "non-critical" part of the
@@ -44,40 +44,42 @@ __up (struct semaphore *sem)
 	wake_up(&sem->wait);
 }
 
-static spinlock_t semaphore_lock = SPIN_LOCK_UNLOCKED;
-
 void
 __down (struct semaphore *sem)
 {
 	struct task_struct *tsk = current;
 	DECLARE_WAITQUEUE(wait, tsk);
+	unsigned long flags;
+
 	tsk->state = TASK_UNINTERRUPTIBLE;
-	add_wait_queue_exclusive(&sem->wait, &wait);
+	spin_lock_irqsave(&sem->wait.lock, flags);
+	add_wait_queue_exclusive_locked(&sem->wait, &wait);
 
-	spin_lock_irq(&semaphore_lock);
 	sem->sleepers++;
 	for (;;) {
 		int sleepers = sem->sleepers;
 
 		/*
 		 * Add "everybody else" into it. They aren't
-		 * playing, because we own the spinlock.
+		 * playing, because we own the spinlock in
+		 * the wait_queue_head.
 		 */
 		if (!atomic_add_negative(sleepers - 1, &sem->count)) {
 			sem->sleepers = 0;
 			break;
 		}
 		sem->sleepers = 1;	/* us - see -1 above */
-		spin_unlock_irq(&semaphore_lock);
+		spin_unlock_irqrestore(&sem->wait.lock, flags);
 
 		schedule();
+
+		spin_lock_irqsave(&sem->wait.lock, flags);
 		tsk->state = TASK_UNINTERRUPTIBLE;
-		spin_lock_irq(&semaphore_lock);
 	}
-	spin_unlock_irq(&semaphore_lock);
-	remove_wait_queue(&sem->wait, &wait);
+	remove_wait_queue_locked(&sem->wait, &wait);
+	wake_up_locked(&sem->wait);
+	spin_unlock_irqrestore(&sem->wait.lock, flags);
 	tsk->state = TASK_RUNNING;
-	wake_up(&sem->wait);
 }
 
 int
@@ -86,10 +88,12 @@ __down_interruptible (struct semaphore * sem)
 	int retval = 0;
 	struct task_struct *tsk = current;
 	DECLARE_WAITQUEUE(wait, tsk);
+	unsigned long flags;
+
 	tsk->state = TASK_INTERRUPTIBLE;
-	add_wait_queue_exclusive(&sem->wait, &wait);
+	spin_lock_irqsave(&sem->wait.lock, flags);
+	add_wait_queue_exclusive_locked(&sem->wait, &wait);
 
-	spin_lock_irq(&semaphore_lock);
 	sem->sleepers ++;
 	for (;;) {
 		int sleepers = sem->sleepers;
@@ -110,25 +114,27 @@ __down_interruptible (struct semaphore * sem)
 
 		/*
 		 * Add "everybody else" into it. They aren't
-		 * playing, because we own the spinlock. The
-		 * "-1" is because we're still hoping to get
-		 * the lock.
+		 * playing, because we own the spinlock in
+		 * wait_queue_head. The "-1" is because we're
+		 * still hoping to get the semaphore.
 		 */
 		if (!atomic_add_negative(sleepers - 1, &sem->count)) {
 			sem->sleepers = 0;
 			break;
 		}
 		sem->sleepers = 1;	/* us - see -1 above */
-		spin_unlock_irq(&semaphore_lock);
+		spin_unlock_irqrestore(&sem->wait.lock, flags);
 
 		schedule();
+
+		spin_lock_irqsave(&sem->wait.lock, flags);
 		tsk->state = TASK_INTERRUPTIBLE;
-		spin_lock_irq(&semaphore_lock);
 	}
-	spin_unlock_irq(&semaphore_lock);
+	remove_wait_queue_locked(&sem->wait, &wait);
+	wake_up_locked(&sem->wait);
+	spin_unlock_irqrestore(&sem->wait.lock, flags);
+
 	tsk->state = TASK_RUNNING;
-	remove_wait_queue(&sem->wait, &wait);
-	wake_up(&sem->wait);
 	return retval;
 }
 
@@ -142,17 +148,19 @@ __down_trylock (struct semaphore *sem)
 	unsigned long flags;
 	int sleepers;
 
-	spin_lock_irqsave(&semaphore_lock, flags);
+	spin_lock_irqsave(&sem->wait.lock, flags);
 	sleepers = sem->sleepers + 1;
 	sem->sleepers = 0;
 
 	/*
 	 * Add "everybody else" and us into it. They aren't
-	 * playing, because we own the spinlock.
+	 * playing, because we own the spinlock in the
+	 * wait_queue_head.
 	 */
-	if (!atomic_add_negative(sleepers, &sem->count))
-		wake_up(&sem->wait);
+	if (!atomic_add_negative(sleepers, &sem->count)) {
+		wake_up_locked(&sem->wait);
+	}
 
-	spin_unlock_irqrestore(&semaphore_lock, flags);
+	spin_unlock_irqrestore(&sem->wait.lock, flags);
 	return 1;
 }