Don,
On 10/17/2016 12:31 PM, Don Zickus wrote:
On Thu, Oct 13, 2016 at 01:38:01PM -0700, Babu Moger wrote:
Currently we do not have a way to enable/disable arch specific
watchdog handlers if it was implemented by any of the architectures.
This patch introduces new functions arch_watchdog_nmi_enable and
arch_watchdog_nmi_disable which can be used to enable/disable architecture
specific NMI watchdog handlers. These functions are defined as weak as
architectures can override their definitions to enable/disable nmi
watchdog behaviour.
Hi Babu,
This patch tested fine on my x86 box and I am ok with the changes.
I do have one small cosmetic request below for a failure path. Other than
that I will give my ack.
Yes. I am testing these changes. If everything goes as expected, I will
post v3 version
tomorrow. Thanks Babu
Cheers,
Don
Signed-off-by: Babu Moger <babu.moger@xxxxxxxxxx>
---
kernel/watchdog.c | 65 +++++++++++++++++++++++++++++++++++-----------------
1 files changed, 44 insertions(+), 21 deletions(-)
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 9acb29f..d1e84e6 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -46,7 +46,7 @@
static DEFINE_MUTEX(watchdog_proc_mutex);
-#ifdef CONFIG_HARDLOCKUP_DETECTOR
+#if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HAVE_NMI_WATCHDOG)
static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED;
#else
static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED;
@@ -585,15 +585,11 @@ static void watchdog(unsigned int cpu)
*/
static unsigned long cpu0_err;
-static int watchdog_nmi_enable(unsigned int cpu)
+static int arch_watchdog_nmi_enable(unsigned int cpu)
{
struct perf_event_attr *wd_attr;
struct perf_event *event = per_cpu(watchdog_ev, cpu);
- /* nothing to do if the hard lockup detector is disabled */
- if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
- goto out;
-
/* is it already setup and enabled? */
if (event && event->state > PERF_EVENT_STATE_OFF)
goto out;
@@ -619,18 +615,6 @@ static int watchdog_nmi_enable(unsigned int cpu)
goto out_save;
}
- /*
- * Disable the hard lockup detector if _any_ CPU fails to set up
- * set up the hardware perf event. The watchdog() function checks
- * the NMI_WATCHDOG_ENABLED bit periodically.
- *
- * The barriers are for syncing up watchdog_enabled across all the
- * cpus, as clear_bit() does not use barriers.
- */
- smp_mb__before_atomic();
- clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled);
- smp_mb__after_atomic();
-
/* skip displaying the same error again */
if (cpu > 0 && (PTR_ERR(event) == cpu0_err))
return PTR_ERR(event);
In the arch_watchdog_nmi_enable code is a pr_info on failure
pr_info("Shutting down hard lockup detector on all cpus\n");
that should be moved to below..
@@ -658,7 +642,7 @@ out:
return 0;
}
-static void watchdog_nmi_disable(unsigned int cpu)
+static void arch_watchdog_nmi_disable(unsigned int cpu)
{
struct perf_event *event = per_cpu(watchdog_ev, cpu);
@@ -676,8 +660,13 @@ static void watchdog_nmi_disable(unsigned int cpu)
}
#else
-static int watchdog_nmi_enable(unsigned int cpu) { return 0; }
-static void watchdog_nmi_disable(unsigned int cpu) { return; }
+/*
+ * These two functions are mostly architecture specific
+ * defining them as weak here.
+ */
+int __weak arch_watchdog_nmi_enable(unsigned int cpu) { return 0; }
+void __weak arch_watchdog_nmi_disable(unsigned int cpu) { return; }
+
#endif /* CONFIG_HARDLOCKUP_DETECTOR */
static struct smp_hotplug_thread watchdog_threads = {
@@ -781,6 +770,40 @@ void lockup_detector_resume(void)
put_online_cpus();
}
+void watchdog_nmi_disable(unsigned int cpu)
+{
+ arch_watchdog_nmi_disable(cpu);
+}
+
+int watchdog_nmi_enable(unsigned int cpu)
+{
+ int err;
+
+ /* nothing to do if the hard lockup detector is disabled */
+ if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
+ return 0;
+
+ err = arch_watchdog_nmi_enable(cpu);
+
+ if (err) {
+ /*
+ * Disable the hard lockup detector if _any_ CPU fails to set up
+ * set up the hardware perf event. The watchdog() function checks
+ * the NMI_WATCHDOG_ENABLED bit periodically.
+ *
+ * The barriers are for syncing up watchdog_enabled across all the
+ * cpus, as clear_bit() does not use barriers.
+ */
+ smp_mb__before_atomic();
+ clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled);
+ smp_mb__after_atomic();
moved to here:
pr_info("Shutting down hard lockup detector on all cpus\n");
This lets the failure message be displayed on all arches instead of just
x86. Though I guess sparc does not call theirs 'hard lockup detector'.
Hmm...
+
+ return err;
+ }
+
+ return 0;
+}
+
static int update_watchdog_all_cpus(void)
{
int ret;
--
1.7.1
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