linux-kernel - [tip:core/locking] futex: Use freezable blocking call

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Date:	Tue, 25 Jun 2013 14:15:51 -0700
From:	tip-bot for Colin Cross <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	dvhart@...ux.intel.com, rdunlap@...radead.org,
	viro@...iv.linux.org.uk, ccross@...roid.com, tj@...nel.org,
	tglx@...utronix.de, oleg@...hat.com, rjw@...k.pl
Subject: [tip:core/locking] futex: Use freezable blocking call

Commit-ID:  88c8004fd3a5fdd2378069de86b90b21110d33a4
Gitweb:     http://git.kernel.org/tip/88c8004fd3a5fdd2378069de86b90b21110d33a4
Author:     Colin Cross <ccross@...roid.com>
AuthorDate: Wed, 1 May 2013 18:35:05 -0700
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Tue, 25 Jun 2013 23:11:19 +0200

futex: Use freezable blocking call

Avoid waking up every thread sleeping in a futex_wait call during
suspend and resume by calling a freezable blocking call.  Previous
patches modified the freezer to avoid sending wakeups to threads
that are blocked in freezable blocking calls.

This call was selected to be converted to a freezable call because
it doesn't hold any locks or release any resources when interrupted
that might be needed by another freezing task or a kernel driver
during suspend, and is a common site where idle userspace tasks are
blocked.

Signed-off-by: Colin Cross <ccross@...roid.com>
Cc: Rafael J. Wysocki <rjw@...k.pl>
Cc: arve@...roid.com
Cc: Tejun Heo <tj@...nel.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Darren Hart <dvhart@...ux.intel.com>
Cc: Randy Dunlap <rdunlap@...radead.org>
Cc: Al Viro <viro@...iv.linux.org.uk>
Link: http://lkml.kernel.org/r/1367458508-9133-8-git-send-email-ccross@android.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 kernel/futex.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 49dacfb..c3a1a55 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -62,6 +62,7 @@
 #include <linux/ptrace.h>
 #include <linux/sched/rt.h>
 #include <linux/hugetlb.h>
+#include <linux/freezer.h>
 
 #include <asm/futex.h>
 
@@ -1808,7 +1809,7 @@ static void futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q *q,
 		 * is no timeout, or if it has yet to expire.
 		 */
 		if (!timeout || timeout->task)
-			schedule();
+			freezable_schedule();
 	}
 	__set_current_state(TASK_RUNNING);
 }
--
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