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@redhat.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 9a1c78769a33c371f0648e6dc6edb330c5880744..dcc4990097a21a2cc100de376149b77c4d180e42 100644 (file)
--- 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
  */