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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: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Paul E. McKenney 2014-01-31 12:58:39 -08:00
parent 628edaa506
commit 57a2fe90fc
1 changed files with 5 additions and 5 deletions
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10
kernel/torture.c
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@ -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);