Subject: [PATCH v3 13/16] futex: use freezable blocking call

From: Colin Cross <[email-masked]>
Date: Mon, 6 May 2013 16:50:18 -0700

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.

Acked-by: Tejun Heo <[email-masked]>
Acked-by: Thomas Gleixner <[email-masked]>
Acked-by: Darren Hart <[email-masked]>
Signed-off-by: Colin Cross <[email-masked]>
---
 kernel/futex.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index b26dcfc..d710fae 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -61,6 +61,7 @@
 #include <linux/nsproxy.h>
 #include <linux/ptrace.h>
 #include <linux/sched/rt.h>
+#include <linux/freezer.h>
 
 #include <asm/futex.h>
 
@@ -1807,7 +1808,7 @@ 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);
 }
-- 
1.8.2.1