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| author | Michal Hocko <mhocko@suse.cz> | 2013-09-24 15:27:29 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-24 17:00:25 -0700 |
| commit | 359e6fab6600562073162348cd4c18c5958296d8 (patch) | |
| tree | a7cd07315603004dc2b00311df8cfa259b863feb /kernel | |
| parent | 4a10c2ac2f368583138b774ca41fac4207911983 (diff) | |
| download | lwn-359e6fab6600562073162348cd4c18c5958296d8.tar.gz lwn-359e6fab6600562073162348cd4c18c5958296d8.zip | |
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')
| -rw-r--r-- | kernel/watchdog.c | 7 |
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; set_sample_period(); /* @@ -544,7 +546,8 @@ int proc_dowatchdog(struct ctl_table *table, int write, watchdog_thresh = old_thresh; watchdog_user_enabled = old_enabled; } - +out: + mutex_unlock(&watchdog_proc_mutex); return err; } #endif /* CONFIG_SYSCTL */ |