fix refrigerator() vs thaw_process() race

refrigerator() can miss a wakeup, "wait event" loop needs a proper memory
ordering.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/power/process.c b/kernel/power/process.c
index 6d566bf7085c0b4fd7803a14cbaabef07269198e..0eb5c420e8edfdba4fe04adea60608e0be6357be 100644 (file)
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -47,8 +47,10 @@ void refrigerator(void)
        recalc_sigpending(); /* We sent fake signal, clean it up */
        spin_unlock_irq(&current->sighand->siglock);
 
-       while (frozen(current)) {
-               current->state = TASK_UNINTERRUPTIBLE;
+       for (;;) {
+               set_current_state(TASK_UNINTERRUPTIBLE);
+               if (!frozen(current))
+                       break;
                schedule();
        }
        pr_debug("%s left refrigerator\n", current->comm);