Commit df577149 authored Aug 11, 2014 by Ulrich Obergfell Committed by Ingo Molnar Aug 18, 2014

watchdog: Fix print-once on enable



This patch avoids printing the message 'enabled on all CPUs,
...' multiple times. For example, the issue can occur in the
following scenario:

1) watchdog_nmi_enable() fails to enable PMU counters and sets
   cpu0_err.

2) 'echo [0|1] > /proc/sys/kernel/nmi_watchdog' is executed to
   disable and re-enable the watchdog mechanism 'on the fly'.

3) If watchdog_nmi_enable() succeeds to enable PMU counters,
   each CPU will print the message because step1 left behind a
   non-zero cpu0_err.

   if (!IS_ERR(event)) {
       if (cpu == 0 || cpu0_err)
           pr_info("enabled on all CPUs, ...")

The patch avoids this by clearing cpu0_err in watchdog_nmi_disable().

Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: pbonzini@redhat.com
Link: http://lkml.kernel.org/r/1407768567-171794-4-git-send-email-dzickus@redhat.com


[ Applied small cleanups. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent f530504a

kernel/watchdog.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -506,7 +506,10 @@ static void watchdog_nmi_disable(unsigned int cpu)
		/* should be in cleanup, but blocks oprofile */
		perf_event_release_kernel(event);
		}
		return;
		if (cpu == 0) {
		/* watchdog_nmi_enable() expects this to be zero initially. */
		cpu0_err = 0;
		}
		}
		#else
		static int watchdog_nmi_enable(unsigned int cpu) { return 0; }

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