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.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/kernel/futex.c b/kernel/futex.c
index b26dcfc02c9489b3ca00bfd076f2208bb4964366..d710fae8abbe933b97267b69ff2e27864d1291a4 100644 (file)
--- 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);
 }