linux-kernel - [PATCH tip/core/rcu 31/55] rcutorture: Apply ACCESS

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 17 Feb 2014 14:12:35 -0800
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...nel.org, laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
	josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de,
	peterz@...radead.org, rostedt@...dmis.org, dhowells@...hat.com,
	edumazet@...gle.com, darren@...art.com, fweisbec@...il.com,
	oleg@...hat.com, sbw@....edu,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 31/55] rcutorture: Apply ACCESS_ONCE() to racy fullstop accesses

From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>

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@...ux.vnet.ibm.com>
---
 kernel/torture.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/torture.c b/kernel/torture.c
index 317b49d8ff79..82a8735472f0 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);
-- 
1.8.1.5

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/