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 <[email protected]> Signed-off-by: Don Zickus <[email protected]> Cc: Ingo Molnar <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
kyagi · Apr 14, 2015 · a0c9cbb · a0c9cbb
1 parent 84d56e6
commit a0c9cbb
Showing 1 changed file with 23 additions and 0 deletions.
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
@@ -678,6 +678,29 @@ 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
  */