Commit 88c8004f authored May 01, 2013 by Colin Cross Committed by Thomas Gleixner Jun 25, 2013

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@android.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: arve@android.com
Cc: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Darren Hart <dvhart@linux.intel.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Link: http://lkml.kernel.org/r/1367458508-9133-8-git-send-email-ccross@android.com


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

parent 13d60f4b

kernel/futex.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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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