[PATCH 3/4] watchdog: disable watchdog when thresh is zero

[Mandeep Singh Baines <msb@chromium.org>]

This restores the previous behavior of softlock_thresh.

Currently, setting watchdog_thresh to zero causes the watchdog
kthreads to consume a lot of CPU.

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
---
 kernel/watchdog.c |   15 ++++++++++++++-
 1 files changed, 14 insertions(+), 1 deletions(-)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index cf0e09f..50c2f62 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -526,7 +526,20 @@ int proc_dowatchdog_thresh(struct ctl_table *table, int write,
 			     void __user *buffer,
 			     size_t *lenp, loff_t *ppos)
 {
-	return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+	int ret;
+
+	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+	if (ret || !write)
+		goto out;
+
+	if (softlockup_thresh)
+		watchdog_enable_all_cpus();
+	else
+		watchdog_disable_all_cpus();
+
+out:
+	return ret;
+
 }
 #endif /* CONFIG_SYSCTL */
 
-- 
1.7.3.1