lockup_detector: Sync touch_*_watchdog back to old semantics

During my rewrite, the semantics of touch_nmi_watchdog and
touch_softlockup_watchdog changed enough to break some drivers
(mostly over preemptable regions).

These are cases where long delays on one CPU (due to
print_delay for example) can cause long delays on other
CPUs - so we must 'touch' the nmi_watchdog flag of those
other CPUs as well.

This change brings those touch_*_watchdog() functions back in line
with to how they used to work.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: peterz@infradead.org
Cc: fweisbec@gmail.com
LKML-Reference: <1283310009-22168-2-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 0d53c8e..7f9c3c5 100644 (file)
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -122,7 +122,7 @@ static void __touch_watchdog(void)
 
 void touch_softlockup_watchdog(void)
 {
-       __get_cpu_var(watchdog_touch_ts) = 0;
+       __raw_get_cpu_var(watchdog_touch_ts) = 0;
 }
 EXPORT_SYMBOL(touch_softlockup_watchdog);
 
@@ -142,7 +142,14 @@ void touch_all_softlockup_watchdogs(void)
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
 void touch_nmi_watchdog(void)
 {
-       __get_cpu_var(watchdog_nmi_touch) = true;
+       if (watchdog_enabled) {
+               unsigned cpu;
+
+               for_each_present_cpu(cpu) {
+                       if (per_cpu(watchdog_nmi_touch, cpu) != true)
+                               per_cpu(watchdog_nmi_touch, cpu) = true;
+               }
+       }
        touch_softlockup_watchdog();
 }
 EXPORT_SYMBOL(touch_nmi_watchdog);
@@ -433,6 +440,9 @@ static int watchdog_enable(int cpu)
                wake_up_process(p);
        }
 
+       /* if any cpu succeeds, watchdog is considered enabled for the system */
+       watchdog_enabled = 1;
+
        return 0;
 }
 
@@ -455,9 +465,6 @@ static void watchdog_disable(int cpu)
                per_cpu(softlockup_watchdog, cpu) = NULL;
                kthread_stop(p);
        }
-
-       /* if any cpu succeeds, watchdog is considered enabled for the system */
-       watchdog_enabled = 1;
 }
 
 static void watchdog_enable_all_cpus(void)