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Subject[PATCH 1/3] watchdog: fix print-once on enable
Date
From: Ulrich Obergfell <uobergfe@redhat.com>

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>
---
kernel/watchdog.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index c3319bd1b0408..c985a21926545 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -511,6 +511,9 @@ 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;
return;
}
#else
--
1.9.3


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