flush_scheduled_tasks() question

[Manfred Spraul]

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Is is intentional that tummy_task is not initialized?
Ok, it won't crash because the current __run_task_queue() implementation
doesn't call tq->routine if it's NULL, but IMHO it's ugly.

Additionally I don't like the loop in flush_scheduled_tasks(), what
about replacing it with a locked semaphore (same idea as vfork)?

I've attched an untested patch.

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	Manfred
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--- context.c.orig	Sun Jan 28 17:02:35 2001
+++ context.c	Sun Jan 28 17:09:24 2001
@@ -22,7 +22,6 @@
 
 static DECLARE_TASK_QUEUE(tq_context);
 static DECLARE_WAIT_QUEUE_HEAD(context_task_wq);
-static DECLARE_WAIT_QUEUE_HEAD(context_task_done);
 static int keventd_running;
 static struct task_struct *keventd_task;
 
@@ -97,7 +96,6 @@
 		schedule();
 		remove_wait_queue(&context_task_wq, &wait);
 		run_task_queue(&tq_context);
-		wake_up(&context_task_done);
 		if (signal_pending(curtask)) {
 			while (waitpid(-1, (unsigned int *)0, __WALL|WNOHANG) > 0)
 				;
@@ -119,31 +117,24 @@
  * The caller should hold no spinlocks and should hold no semaphores which could
  * cause the scheduled tasks to block.
  */
-static struct tq_struct dummy_task;
 
-void flush_scheduled_tasks(void)
+static void up_semaphore(void* sem)
 {
-	int count;
-	DECLARE_WAITQUEUE(wait, current);
+	up((struct semaphore*)sem);
+}
 
-	/*
-	 * Do it twice. It's possible, albeit highly unlikely, that
-	 * the caller queued a task immediately before calling us,
-	 * and that the eventd thread was already past the run_task_queue()
-	 * but not yet into wake_up(), so it woke us up before completing
-	 * the caller's queued task or our new dummy task.
-	 */
-	add_wait_queue(&context_task_done, &wait);
-	for (count = 0; count < 2; count++) {
-		set_current_state(TASK_UNINTERRUPTIBLE);
+void flush_scheduled_tasks(void)
+{
+	DECLARE_MUTEX_LOCKED(sem);
+	struct tq_struct wakeup_task;
 
-		/* Queue a dummy task to make sure we get kicked */
-		schedule_task(&dummy_task);
+	wakeup_task.routine = up_semaphore;
+	wakeup_task.data = &sem;
+	/* Queue a dummy task to make sure we get kicked */
+	schedule_task(&dummy_task);
 
-		/* Wait for it to complete */
-		schedule();
-	}
-	remove_wait_queue(&context_task_done, &wait);
+	/* Wait for it to complete */
+	down(&sem);
 }
 	
 int start_context_thread(void)

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