path: root/kernel
diff options
authorMichal Hocko <mhocko@suse.cz>2013-09-24 15:27:29 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-24 17:00:25 -0700
commit359e6fab6600562073162348cd4c18c5958296d8 (patch)
treea7cd07315603004dc2b00311df8cfa259b863feb /kernel
parentLinux 3.12-rc2 (diff)
watchdog: update watchdog attributes atomically
proc_dowatchdog doesn't synchronize multiple callers which might lead to confusion when two parallel callers might confuse watchdog_enable_all_cpus resp watchdog_disable_all_cpus (eg watchdog gets enabled even if watchdog_thresh was set to 0 already). This patch adds a local mutex which synchronizes callers to the sysctl handler. Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Don Zickus <dzickus@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 51c4f34d258e..ced7d0609931 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -520,13 +520,15 @@ int proc_dowatchdog(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
int err, old_thresh, old_enabled;
+ static DEFINE_MUTEX(watchdog_proc_mutex);
+ mutex_lock(&watchdog_proc_mutex);
old_thresh = ACCESS_ONCE(watchdog_thresh);
old_enabled = ACCESS_ONCE(watchdog_user_enabled);
err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
if (err || !write)
- return err;
+ goto out;
@@ -544,7 +546,8 @@ int proc_dowatchdog(struct ctl_table *table, int write,
watchdog_thresh = old_thresh;
watchdog_user_enabled = old_enabled;
+ mutex_unlock(&watchdog_proc_mutex);
return err;
#endif /* CONFIG_SYSCTL */