Re: [patch] wait_for_completion(_interruptible)?(_timeout)?

[Mike Waychison]

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Mike Waychison wrote:
> Hi Thomas, Ingo,
> 
> I've tried using the wait_for_completion_interruptible from the patch
> posted to lkml (http://lkml.org/lkml/2004/10/20/461).
> 
> It appears that the timeout/sigpending paths don't call
> __remove_wait_queue, which is bad when somebody gets around to calling
> complete_all.
> 
> Fixed up patch attached.
> 

Ugh.  I must have been half asleep when I originally sent.  The attached
patch does the fix properly (without the two other typos in the two
_timeout variants).


- --
Mike Waychison
Sun Microsystems, Inc.
1 (650) 352-5299 voice
1 (416) 202-8336 voice

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Additional functions for the completion API.

wait_for_completion_interruptible()
wait_for_completion_timeout()
wait_for_completion_interruptible_timeout()

Those are neccecary to convert the users of the racy and 
obsolete sleep_on variants to the completion API

Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Mike Waychison <michael.waychison@xxxxxxx>

Index: linux-2.6.9-quilt/include/linux/completion.h
===================================================================
--- linux-2.6.9-quilt.orig/include/linux/completion.h	2004-11-23 20:47:36.000000000 -0800
+++ linux-2.6.9-quilt/include/linux/completion.h	2004-11-23 20:47:39.000000000 -0800
@@ -28,6 +28,12 @@ static inline void init_completion(struc
 }
 
 extern void FASTCALL(wait_for_completion(struct completion *));
+extern int FASTCALL(wait_for_completion_interruptible(struct completion *));
+extern unsigned long FASTCALL(wait_for_completion_timeout(struct completion *,
+							  unsigned long));
+extern unsigned long FASTCALL(wait_for_completion_timeout_interruptible
+			(struct completion *, unsigned long));
+
 extern void FASTCALL(complete(struct completion *));
 extern void FASTCALL(complete_all(struct completion *));
 
Index: linux-2.6.9-quilt/kernel/sched.c
===================================================================
--- linux-2.6.9-quilt.orig/kernel/sched.c	2004-11-23 20:47:36.000000000 -0800
+++ linux-2.6.9-quilt/kernel/sched.c	2004-11-24 07:36:45.400598432 -0800
@@ -2957,6 +2957,106 @@ void fastcall __sched wait_for_completio
 }
 EXPORT_SYMBOL(wait_for_completion);
 
+unsigned long fastcall __sched
+wait_for_completion_timeout(struct completion *x, unsigned long timeout)
+{
+	might_sleep();
+
+	spin_lock_irq(&x->wait.lock);
+	if (!x->done) {
+		DECLARE_WAITQUEUE(wait, current);
+
+		wait.flags |= WQ_FLAG_EXCLUSIVE;
+		__add_wait_queue_tail(&x->wait, &wait);
+		do {
+			__set_current_state(TASK_UNINTERRUPTIBLE);
+			spin_unlock_irq(&x->wait.lock);
+			timeout = schedule_timeout(timeout);
+			spin_lock_irq(&x->wait.lock);
+			if (!timeout) {
+				__remove_wait_queue(&x->wait, &wait);
+				goto out;
+			}
+		} while (!x->done);
+		__remove_wait_queue(&x->wait, &wait);
+	}
+	x->done--;
+out:
+	spin_unlock_irq(&x->wait.lock);
+	return timeout;
+}
+EXPORT_SYMBOL(wait_for_completion_timeout);
+
+int fastcall __sched wait_for_completion_interruptible(struct completion *x)
+{
+	int ret = 0;
+
+	might_sleep();
+
+	spin_lock_irq(&x->wait.lock);
+	if (!x->done) {
+		DECLARE_WAITQUEUE(wait, current);
+
+		wait.flags |= WQ_FLAG_EXCLUSIVE;
+		__add_wait_queue_tail(&x->wait, &wait);
+		do {
+			if (signal_pending(current)) {
+				ret = -ERESTARTSYS;
+				__remove_wait_queue(&x->wait, &wait);
+				goto out;
+			}
+			__set_current_state(TASK_INTERRUPTIBLE);
+			spin_unlock_irq(&x->wait.lock);
+			schedule();
+			spin_lock_irq(&x->wait.lock);
+		} while (!x->done);
+		__remove_wait_queue(&x->wait, &wait);
+	}
+	x->done--;
+out:
+	spin_unlock_irq(&x->wait.lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(wait_for_completion_interruptible);
+
+unsigned long fastcall __sched
+wait_for_completion_interruptible_timeout(struct completion *x,
+					  unsigned long timeout)
+{
+	might_sleep();
+
+	spin_lock_irq(&x->wait.lock);
+	if (!x->done) {
+		DECLARE_WAITQUEUE(wait, current);
+
+		wait.flags |= WQ_FLAG_EXCLUSIVE;
+		__add_wait_queue_tail(&x->wait, &wait);
+		do {
+			if (signal_pending(current)) {
+				timeout = -ERESTARTSYS;
+				__remove_wait_queue(&x->wait, &wait);
+				goto out_unlock;
+			}
+			__set_current_state(TASK_INTERRUPTIBLE);
+			spin_unlock_irq(&x->wait.lock);
+			timeout = schedule_timeout(timeout);
+			spin_lock_irq(&x->wait.lock);
+			if (!timeout) {
+				__remove_wait_queue(&x->wait, &wait);
+				goto out_unlock;
+			}
+		} while (!x->done);
+		__remove_wait_queue(&x->wait, &wait);
+	}
+	x->done--;
+out_unlock:
+	spin_unlock_irq(&x->wait.lock);
+	return timeout;
+}
+EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
+
+
 #define	SLEEP_ON_VAR					\
 	unsigned long flags;				\
 	wait_queue_t wait;				\