From: Paul E. McKenney Date: Fri, 31 Jan 2014 20:58:39 +0000 (-0800) Subject: rcutorture: Apply ACCESS_ONCE() to racy fullstop accesses X-Git-Tag: submit/tizen/20160607.132125~4922^2~1^2^2~23 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=57a2fe90fcdaa812ac1aa6c91ba0e591c30f461a;p=sdk%2Femulator%2Femulator-kernel.git rcutorture: Apply ACCESS_ONCE() to racy fullstop accesses Because the fullstop variable can be accessed while it is being updated, this commit avoids any resulting compiler mischief through use of ACCESS_ONCE() for non-initialization accesses to this shared variable. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- diff --git a/kernel/torture.c b/kernel/torture.c index b30c2ee..1bafd02 100644 --- a/kernel/torture.c +++ b/kernel/torture.c @@ -439,9 +439,9 @@ static int torture_shutdown_notify(struct notifier_block *unused1, unsigned long unused2, void *unused3) { mutex_lock(&fullstop_mutex); - if (fullstop == FULLSTOP_DONTSTOP) { + if (ACCESS_ONCE(fullstop) == FULLSTOP_DONTSTOP) { VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected"); - fullstop = FULLSTOP_SHUTDOWN; + ACCESS_ONCE(fullstop) = FULLSTOP_SHUTDOWN; } else { pr_warn("Concurrent rmmod and shutdown illegal!\n"); } @@ -575,13 +575,13 @@ EXPORT_SYMBOL_GPL(torture_init_end); bool torture_cleanup(void) { mutex_lock(&fullstop_mutex); - if (fullstop == FULLSTOP_SHUTDOWN) { + if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) { pr_warn("Concurrent rmmod and shutdown illegal!\n"); mutex_unlock(&fullstop_mutex); schedule_timeout_uninterruptible(10); return true; } - fullstop = FULLSTOP_RMMOD; + ACCESS_ONCE(fullstop) = FULLSTOP_RMMOD; mutex_unlock(&fullstop_mutex); unregister_reboot_notifier(&torture_shutdown_nb); torture_shuffle_cleanup(); @@ -605,6 +605,6 @@ EXPORT_SYMBOL_GPL(torture_must_stop); */ bool torture_must_stop_irq(void) { - return fullstop != FULLSTOP_DONTSTOP; + return ACCESS_ONCE(fullstop) != FULLSTOP_DONTSTOP; } EXPORT_SYMBOL_GPL(torture_must_stop_irq);