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Commit 57a2fe90 authored by Paul E. McKenney's avatar Paul E. McKenney
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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: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent 628edaa5

kernel/torture.c

+5 −5
Original line number Original line Diff line number Diff line
@@ -439,9 +439,9 @@ static int torture_shutdown_notify(struct notifier_block *unused1, 
				   unsigned long unused2, void *unused3)

				   unsigned long unused2, void *unused3)

{

{

	mutex_lock(&fullstop_mutex);

	mutex_lock(&fullstop_mutex);

	if (fullstop == FULLSTOP_DONTSTOP) {

	if (ACCESS_ONCE(fullstop) == FULLSTOP_DONTSTOP) {

		VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");

		VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");

		fullstop = FULLSTOP_SHUTDOWN;

		ACCESS_ONCE(fullstop) = FULLSTOP_SHUTDOWN;

	} else {

	} else {

		pr_warn("Concurrent rmmod and shutdown illegal!\n");

		pr_warn("Concurrent rmmod and shutdown illegal!\n");

	}

	}
@@ -575,13 +575,13 @@ EXPORT_SYMBOL_GPL(torture_init_end); 
bool torture_cleanup(void)

bool torture_cleanup(void)

{

{

	mutex_lock(&fullstop_mutex);

	mutex_lock(&fullstop_mutex);

	if (fullstop == FULLSTOP_SHUTDOWN) {

	if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {

		pr_warn("Concurrent rmmod and shutdown illegal!\n");

		pr_warn("Concurrent rmmod and shutdown illegal!\n");

		mutex_unlock(&fullstop_mutex);

		mutex_unlock(&fullstop_mutex);

		schedule_timeout_uninterruptible(10);

		schedule_timeout_uninterruptible(10);

		return true;

		return true;

	}

	}

	fullstop = FULLSTOP_RMMOD;

	ACCESS_ONCE(fullstop) = FULLSTOP_RMMOD;

	mutex_unlock(&fullstop_mutex);

	mutex_unlock(&fullstop_mutex);

	unregister_reboot_notifier(&torture_shutdown_nb);

	unregister_reboot_notifier(&torture_shutdown_nb);

	torture_shuffle_cleanup();

	torture_shuffle_cleanup();
@@ -605,6 +605,6 @@ EXPORT_SYMBOL_GPL(torture_must_stop); 
 */

 */

bool torture_must_stop_irq(void)

bool torture_must_stop_irq(void)

{

{

	return fullstop != FULLSTOP_DONTSTOP;

	return ACCESS_ONCE(fullstop) != FULLSTOP_DONTSTOP;

}

}

EXPORT_SYMBOL_GPL(torture_must_stop_irq);
 
EXPORT_SYMBOL_GPL(torture_must_stop_irq);