linux-kernel - [PATCH v2 2/9] watchdog: introduce the proc_watchdog

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Message-Id: <1413565588-4144-3-git-send-email-uobergfe@redhat.com>
Date:	Fri, 17 Oct 2014 19:06:21 +0200
From:	Ulrich Obergfell <uobergfe@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	dzickus@...hat.com, uobergfe@...hat.com
Subject: [PATCH v2 2/9] watchdog: introduce the proc_watchdog_update() function

This series introduces a separate handler for each watchdog parameter
in /proc/sys/kernel. The separate handlers need a common function that
they can call to update the run state of the lockup detectors, or to
have the lockup detectors use a new sample period.

Signed-off-by: Ulrich Obergfell <uobergfe@...hat.com>
---
 kernel/watchdog.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index f8da756..da16a50 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -679,6 +679,29 @@ static void watchdog_disable_all_cpus(void)
 }
 
 /*
+ * Update the run state of the lockup detectors.
+ */
+static int proc_watchdog_update(void)
+{
+	int err = 0;
+
+	/*
+	 * Watchdog threads won't be started if they are already active.
+	 * The 'watchdog_running' variable in watchdog_*_all_cpus() takes
+	 * care of this. If those threads are already active, the sample
+	 * period will be updated and the lockup detectors will be enabled
+	 * or disabled 'on the fly'.
+	 */
+	if (watchdog_enabled && watchdog_thresh)
+		err = watchdog_enable_all_cpus(true);
+	else
+		watchdog_disable_all_cpus();
+
+	return err;
+
+}
+
+/*
  * proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh
  */
 
-- 
1.7.11.7

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