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Date: Mon, 17 May 2010 18:06:05 -0400
From: Don Zickus <dzickus@...hat.com>
To: fweisbec@...il.com, mingo@...e.hu
Cc: a.p.zijlstra@...llo.nl, gorcunov@...il.com,
linux-kernel@...r.kernel.org, Don Zickus <dzickus@...hat.com>
Subject: [PATCH 2/3] [watchdog] separate hardlockup/softlockup enable paths
In preparation to support the backwards compatible option nmi_watchdog properly
from the kernel commandline, the enable/disable paths for the hardlockup and
softlockup code needed to separated more cleanly.
The code is re-arranged a bit to create a watchdog_softlockup_enable/disable
function to mimic the hardlockup counterpart. In addition, a softlockup callback
is created to make it easy to turn the softlockup code on/off with out interfering
with the hardlockup code.
The functionality should still be the same.
Signed-off-by: Don Zickus <dzickus@...hat.com>
---
kernel/watchdog.c | 92 ++++++++++++++++++++++++++++++++++++-----------------
1 files changed, 63 insertions(+), 29 deletions(-)
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 91b0b26..0a6bdb7 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -30,9 +30,12 @@
int watchdog_enabled;
int __read_mostly softlockup_thresh = 60;
+typedef void (*callback_t)(void);
+
static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
-static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
+static DEFINE_PER_CPU(struct task_struct *, watchdog_thread);
static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
+static DEFINE_PER_CPU(callback_t, softlockup_callback);
static DEFINE_PER_CPU(bool, softlockup_touch_sync);
static DEFINE_PER_CPU(bool, soft_watchdog_warn);
#ifdef CONFIG_HARDLOCKUP_DETECTOR
@@ -244,21 +247,14 @@ static void watchdog_interrupt_count(void)
static inline void watchdog_interrupt_count(void) { return; }
#endif /* CONFIG_HARDLOCKUP_DETECTOR */
-/* watchdog kicker functions */
-static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
+static void watchdog_softlockup_callback(void)
{
unsigned long touch_ts = __get_cpu_var(watchdog_touch_ts);
struct pt_regs *regs = get_irq_regs();
int duration;
- /* kick the hardlockup detector */
- watchdog_interrupt_count();
-
/* kick the softlockup detector */
- wake_up_process(__get_cpu_var(softlockup_watchdog));
-
- /* .. and repeat */
- hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period()));
+ wake_up_process(__get_cpu_var(watchdog_thread));
if (touch_ts == 0) {
if (unlikely(__get_cpu_var(softlockup_touch_sync))) {
@@ -270,7 +266,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
sched_clock_tick();
}
__touch_watchdog();
- return HRTIMER_RESTART;
+ return;
}
/* check for a softlockup
@@ -283,7 +279,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
if (unlikely(duration)) {
/* only warn once */
if (__get_cpu_var(soft_watchdog_warn) == true)
- return HRTIMER_RESTART;
+ return;
printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
smp_processor_id(), duration,
@@ -301,6 +297,24 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
} else
__get_cpu_var(soft_watchdog_warn) = false;
+ return;
+}
+
+/* watchdog kicker functions */
+static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
+{
+ callback_t cb = __get_cpu_var(softlockup_callback);
+
+ /* setup next timer */
+ hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period()));
+
+ /* kick the hardlockup detector */
+ watchdog_interrupt_count();
+
+ /* check the softlockup detector */
+ if (cb)
+ cb();
+
return HRTIMER_RESTART;
}
@@ -397,12 +411,27 @@ static int watchdog_nmi_enable(int cpu) { return 0; }
static void watchdog_nmi_disable(int cpu) { return; }
#endif /* CONFIG_HARDLOCKUP_DETECTOR */
+static int watchdog_softlockup_enable(int cpu)
+{
+ /* if any cpu succeeds, watchdog is considered enabled for the system */
+ per_cpu(softlockup_callback, cpu) = watchdog_softlockup_callback;
+ wake_up_process(per_cpu(watchdog_thread, cpu));
+
+ return 0;
+}
+
+static void watchdog_softlockup_disable(int cpu)
+{
+ per_cpu(softlockup_callback, cpu) = NULL;
+ return;
+}
+
/* prepare/enable/disable routines */
static int watchdog_prepare_cpu(int cpu)
{
struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
- WARN_ON(per_cpu(softlockup_watchdog, cpu));
+ WARN_ON(per_cpu(watchdog_thread, cpu));
hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hrtimer->function = watchdog_timer_fn;
@@ -411,11 +440,8 @@ static int watchdog_prepare_cpu(int cpu)
static int watchdog_enable(int cpu)
{
- struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
-
- /* enable the perf event */
- if (watchdog_nmi_enable(cpu) != 0)
- return -1;
+ struct task_struct *p = per_cpu(watchdog_thread, cpu);
+ int result;
/* create the watchdog thread */
if (!p) {
@@ -426,35 +452,43 @@ static int watchdog_enable(int cpu)
}
kthread_bind(p, cpu);
per_cpu(watchdog_touch_ts, cpu) = 0;
- per_cpu(softlockup_watchdog, cpu) = p;
- wake_up_process(p);
+ per_cpu(watchdog_thread, cpu) = p;
+
}
- return 0;
+ /* enable the hardlockup detector */
+ if (watchdog_nmi_enable(cpu) != 0)
+ result += 1;
+
+ /* enable the softlockup detector */
+ if (watchdog_softlockup_enable(cpu) != 0)
+ result += 1;
+
+ return result;
}
static void watchdog_disable(int cpu)
{
- struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
+ struct task_struct *p = per_cpu(watchdog_thread, cpu);
struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
+ /* disable the hardlockup detector */
+ watchdog_nmi_disable(cpu);
+
+ /* disable the softlockup detector */
+ watchdog_softlockup_disable(cpu);
+
/*
* cancel the timer first to stop incrementing the stats
* and waking up the kthread
*/
hrtimer_cancel(hrtimer);
- /* disable the perf event */
- watchdog_nmi_disable(cpu);
-
/* stop the watchdog thread */
if (p) {
- per_cpu(softlockup_watchdog, cpu) = NULL;
+ per_cpu(watchdog_thread, 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)
--
1.7.0.1
--
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