From 26073428b040223201cc8f52f2a3232149ea8a4f Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Fri, 11 Jan 2013 11:23:51 +0100
Subject: completion: Use simple wait queues

Completions have no long lasting callbacks and therefor do not need
the complex waitqueue variant. Use simple waitqueues which reduces the
contention on the waitqueue lock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/completion.h b/include/linux/completion.h
index 3cd574d..eb2d4ac 100644
--- a/include/linux/completion.h
+++ b/include/linux/completion.h
@@ -8,7 +8,7 @@
  * See kernel/sched/core.c for details.
  */
 
-#include <linux/wait.h>
+#include <linux/wait-simple.h>
 
 /*
  * struct completion - structure used to maintain state for a "completion"
@@ -24,11 +24,11 @@
  */
 struct completion {
 	unsigned int done;
-	wait_queue_head_t wait;
+	struct swait_head wait;
 };
 
 #define COMPLETION_INITIALIZER(work) \
-	{ 0, __WAIT_QUEUE_HEAD_INITIALIZER((work).wait) }
+	{ 0, SWAIT_HEAD_INITIALIZER((work).wait) }
 
 #define COMPLETION_INITIALIZER_ONSTACK(work) \
 	({ init_completion(&work); work; })
@@ -73,7 +73,7 @@ struct completion {
 static inline void init_completion(struct completion *x)
 {
 	x->done = 0;
-	init_waitqueue_head(&x->wait);
+	init_swait_head(&x->wait);
 }
 
 extern void wait_for_completion(struct completion *);
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index 06f28be..d115f62 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -26,6 +26,7 @@
 
 #include <linux/errno.h>
 #include <linux/rbtree.h>
+#include <linux/wait.h>
 
 struct vm_area_struct;
 struct mm_struct;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5ef3a68..c8ce254 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2424,7 +2424,10 @@ void migrate_disable(void)
 	}
 
 #ifdef CONFIG_SCHED_DEBUG
-	WARN_ON_ONCE(p->migrate_disable_atomic);
+	if (unlikely(p->migrate_disable_atomic)) {
+		tracing_off();
+		WARN_ON_ONCE(1);
+	}
 #endif
 
 	if (p->migrate_disable) {
@@ -2455,7 +2458,10 @@ void migrate_enable(void)
 	}
 
 #ifdef CONFIG_SCHED_DEBUG
-	WARN_ON_ONCE(p->migrate_disable_atomic);
+	if (unlikely(p->migrate_disable_atomic)) {
+		tracing_off();
+		WARN_ON_ONCE(1);
+	}
 #endif
 	WARN_ON_ONCE(p->migrate_disable <= 0);
 
@@ -2913,10 +2919,10 @@ void complete(struct completion *x)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&x->wait.lock, flags);
+	raw_spin_lock_irqsave(&x->wait.lock, flags);
 	x->done++;
-	__wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL);
-	spin_unlock_irqrestore(&x->wait.lock, flags);
+	__swait_wake_locked(&x->wait, TASK_NORMAL, 1);
+	raw_spin_unlock_irqrestore(&x->wait.lock, flags);
 }
 EXPORT_SYMBOL(complete);
 
@@ -2933,10 +2939,10 @@ void complete_all(struct completion *x)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&x->wait.lock, flags);
+	raw_spin_lock_irqsave(&x->wait.lock, flags);
 	x->done += UINT_MAX/2;
-	__wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL);
-	spin_unlock_irqrestore(&x->wait.lock, flags);
+	__swait_wake_locked(&x->wait, TASK_NORMAL, 0);
+	raw_spin_unlock_irqrestore(&x->wait.lock, flags);
 }
 EXPORT_SYMBOL(complete_all);
 
@@ -2945,20 +2951,20 @@ do_wait_for_common(struct completion *x,
 		   long (*action)(long), long timeout, int state)
 {
 	if (!x->done) {
-		DECLARE_WAITQUEUE(wait, current);
+		DEFINE_SWAITER(wait);
 
-		__add_wait_queue_tail_exclusive(&x->wait, &wait);
+		swait_prepare_locked(&x->wait, &wait);
 		do {
 			if (signal_pending_state(state, current)) {
 				timeout = -ERESTARTSYS;
 				break;
 			}
 			__set_current_state(state);
-			spin_unlock_irq(&x->wait.lock);
+			raw_spin_unlock_irq(&x->wait.lock);
 			timeout = action(timeout);
-			spin_lock_irq(&x->wait.lock);
+			raw_spin_lock_irq(&x->wait.lock);
 		} while (!x->done && timeout);
-		__remove_wait_queue(&x->wait, &wait);
+		swait_finish_locked(&x->wait, &wait);
 		if (!x->done)
 			return timeout;
 	}
@@ -2972,9 +2978,9 @@ __wait_for_common(struct completion *x,
 {
 	might_sleep();
 
-	spin_lock_irq(&x->wait.lock);
+	raw_spin_lock_irq(&x->wait.lock);
 	timeout = do_wait_for_common(x, action, timeout, state);
-	spin_unlock_irq(&x->wait.lock);
+	raw_spin_unlock_irq(&x->wait.lock);
 	return timeout;
 }
 
@@ -3150,12 +3156,12 @@ bool try_wait_for_completion(struct completion *x)
 	unsigned long flags;
 	int ret = 1;
 
-	spin_lock_irqsave(&x->wait.lock, flags);
+	raw_spin_lock_irqsave(&x->wait.lock, flags);
 	if (!x->done)
 		ret = 0;
 	else
 		x->done--;
-	spin_unlock_irqrestore(&x->wait.lock, flags);
+	raw_spin_unlock_irqrestore(&x->wait.lock, flags);
 	return ret;
 }
 EXPORT_SYMBOL(try_wait_for_completion);
@@ -3173,10 +3179,10 @@ bool completion_done(struct completion *x)
 	unsigned long flags;
 	int ret = 1;
 
-	spin_lock_irqsave(&x->wait.lock, flags);
+	raw_spin_lock_irqsave(&x->wait.lock, flags);
 	if (!x->done)
 		ret = 0;
-	spin_unlock_irqrestore(&x->wait.lock, flags);
+	raw_spin_unlock_irqrestore(&x->wait.lock, flags);
 	return ret;
 }
 EXPORT_SYMBOL(completion_done);
-- 
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