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 (e.g. 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 <mho...@suse.cz>
---
kernel/watchdog.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 1241d8c..2d64c02 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 */
--
1.8.3.2
--
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