kernel/watchdog.c: disable nmi perf event in the error path of enabling watchdog

In corner cases where softlockup watchdog is not setup successfully, the
relevant nmi perf event for hardlockup watchdog could be disabled, then
the status of the underlying hardware remains unchanged.

Also, if the kthread doesn't start then the hrtimer won't run and the
hardlockup detector will falsely fire.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 140dce750450..14733d4d156b 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -430,9 +430,12 @@ static int watchdog_enable(int cpu)
                 p = kthread_create(watchdog, (void *)(unsigned long)cpu, "watchdog/%d", cpu);
                 if (IS_ERR(p)) {
                         printk(KERN_ERR "softlockup watchdog for %i failed\n", cpu);
-                        if (!err)
+                        if (!err) {
                                 /* if hardlockup hasn't already set this */
                                 err = PTR_ERR(p);
+                                /* and disable the perf event */
+                                watchdog_nmi_disable(cpu);
+                        }
                         goto out;
                 }
                 kthread_bind(p, cpu);