* Don Zickus <dzickus@xxxxxxxxxx> wrote:
> From: Ulrich Obergfell <uobergfe@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx>
> Signed-off-by: Don Zickus <dzickus@xxxxxxxxxx>
> ---
> kernel/watchdog.c | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/watchdog.c b/kernel/watchdog.c
> index 6d0a891..0838685 100644
> --- a/kernel/watchdog.c
> +++ b/kernel/watchdog.c
> @@ -522,6 +522,9 @@ static void watchdog_nmi_disable(unsigned int cpu)
> /* should be in cleanup, but blocks oprofile */
> perf_event_release_kernel(event);
> }
> + if (cpu == 0)
> + /* watchdog_nmi_enable() expects this to be zero initially. */
> + cpu0_err = 0;
Looks good except a small detail: two-line blocks need curly
braces too, even if it's just a single C statement. I've fixed
this up in the commit.
thanks,
Ingo
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