From df577149594cefacd62740e86de080c6336d699e Mon Sep 17 00:00:00 2001 From: Ulrich Obergfell Date: Mon, 11 Aug 2014 10:49:25 -0400 Subject: [PATCH] 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 Signed-off-by: Andrew Jones Signed-off-by: Don Zickus 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 --- kernel/watchdog.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 4c2e11ce5425..df5494edf694 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -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; }