linux-kernel - [PATCH 1/5] watchdog: fix error handling in proc_watchdog

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Date:	Mon, 28 Sep 2015 22:44:08 +0200
From:	Ulrich Obergfell <uobergfe@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	akpm@...ux-foundation.org, dzickus@...hat.com, atomlin@...hat.com,
	uobergfe@...hat.com
Subject: [PATCH 1/5] watchdog: fix error handling in proc_watchdog_thresh()

Restore the previous value of watchdog_thresh _and_ sample_period
if proc_watchdog_update() returns an error. The variables must be
consistent to avoid false positives of the lockup detectors.

Signed-off-by: Ulrich Obergfell <uobergfe@...hat.com>
---
 kernel/watchdog.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 64ed1c3..cd9a504 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -914,13 +914,14 @@ int proc_watchdog_thresh(struct ctl_table *table, int write,
 		goto out;
 
 	/*
-	 * Update the sample period.
-	 * Restore 'watchdog_thresh' on failure.
+	 * Update the sample period. Restore on failure.
 	 */
 	set_sample_period();
 	err = proc_watchdog_update();
-	if (err)
+	if (err) {
 		watchdog_thresh = old;
+		set_sample_period();
+	}
 out:
 	mutex_unlock(&watchdog_proc_mutex);
 	return err;
-- 
1.7.11.7

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