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x86: hpet: Fix HPET timer + NMI watchdog panic

PATCH In review Yan, Zheng 2 participants 2 messages Dec 29, 2010 – Jan 3, 2011

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x86 Hpet: x86
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Yan, Zheng

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#0 lore raw

PATCH 1/1 x86: hpet: Fix HPET timer + NMI watchdog panic

HPET doesn't use timer_interrupt() as interrupt handler now. So count of HPET interrupt isn't recorded in per_cpu(irq_stat, cpu).irq0_irqs. This confuses NMI watchdog when using HPET as tick device.

Signed-off-by Yan, Zheng <[email protected]>

---

arch/x86/include/asm/hardirq.h +3 -0
index 55e4de6..cca94f2 100644
@@ -12,6 +12,9 @@ typedef struct {
 	unsigned int apic_timer_irqs;	/* arch dependent */
 	unsigned int irq_spurious_count;
 #endif
+#ifdef CONFIG_HPET_TIMER
+	unsigned int hpet_timer_irqs;
+#endif
 	unsigned int x86_platform_ipis;	/* arch dependent */
 	unsigned int apic_perf_irqs;
 	unsigned int apic_irq_work_irqs;
arch/x86/kernel/apic/nmi.c +8 -1
index c90041c..cdb38d9 100644
@@ -80,8 +80,15 @@ static inline int mce_in_progress(void)
  */
 static inline unsigned int get_timer_irqs(int cpu)
 {
-	return per_cpu(irq_stat, cpu).apic_timer_irqs +
+	unsigned int irqs; 
+#ifdef CONFIG_HPET_TIMER
+	irqs = per_cpu(irq_stat, cpu).hpet_timer_irqs;
+#else
+	irqs = 0;
+#endif
+	irqs += per_cpu(irq_stat, cpu).apic_timer_irqs +
 		per_cpu(irq_stat, cpu).irq0_irqs;
+	return irqs;
 }
 
 #ifdef CONFIG_SMP
arch/x86/kernel/hpet.c +1 -0
index 4ff5968..b536474c 100644
@@ -517,6 +517,7 @@ static irqreturn_t hpet_interrupt_handler(int irq, void *data)
 	struct hpet_dev *dev = (struct hpet_dev *)data;
 	struct clock_event_device *hevt = &dev->evt;
 
+	inc_irq_stat(hpet_timer_irqs);
 	if (!hevt->event_handler) {
 		printk(KERN_INFO "Spurious HPET timer interrupt on HPET timer %d\n",
 				dev->num);
arch/x86/kernel/time.c +1 -1
index fb5cc5e1..2098c56 100644
@@ -56,7 +56,7 @@ unsigned long profile_pc(struct pt_regs *regs)
 EXPORT_SYMBOL(profile_pc);
 
 /*
- * Default timer interrupt handler for PIT/HPET
+ * Default timer interrupt handler for PIT
  */
 static irqreturn_t timer_interrupt(int irq, void *dev_id)
 {
#1 lore raw
Quoted 5 lines · Zheng

HPET doesn't use timer_interrupt() as interrupt handler now. So count of HPET interrupt isn't recorded in per_cpu(irq_stat, cpu).irq0_irqs. This confuses NMI watchdog when using HPET as tick device.

Signed-off-by Yan, Zheng <[email protected]>

Not sure if this patch is needed because x86/kerne/apic/nmi.c will most likely disappear in 2.6.38 (it is already in gone in linux-next). The new nmi watchdog doesn't rely on HPET stats but instead uses a more generic approach of a HRES timer.

Cheers,
Don

Quoted 68 lines

---

arch/x86/include/asm/hardirq.h +3 -0
index 55e4de6..cca94f2 100644
@@ -12,6 +12,9 @@ typedef struct {
 	unsigned int apic_timer_irqs;	/* arch dependent */
 	unsigned int irq_spurious_count;
 #endif
+#ifdef CONFIG_HPET_TIMER
+	unsigned int hpet_timer_irqs;
+#endif
 	unsigned int x86_platform_ipis;	/* arch dependent */
 	unsigned int apic_perf_irqs;
 	unsigned int apic_irq_work_irqs;
arch/x86/kernel/apic/nmi.c +8 -1
index c90041c..cdb38d9 100644
@@ -80,8 +80,15 @@ static inline int mce_in_progress(void)
  */
 static inline unsigned int get_timer_irqs(int cpu)
 {
-	return per_cpu(irq_stat, cpu).apic_timer_irqs +
+	unsigned int irqs; 
+#ifdef CONFIG_HPET_TIMER
+	irqs = per_cpu(irq_stat, cpu).hpet_timer_irqs;
+#else
+	irqs = 0;
+#endif
+	irqs += per_cpu(irq_stat, cpu).apic_timer_irqs +
 		per_cpu(irq_stat, cpu).irq0_irqs;
+	return irqs;
 }
 
 #ifdef CONFIG_SMP
arch/x86/kernel/hpet.c +1 -0
index 4ff5968..b536474c 100644
@@ -517,6 +517,7 @@ static irqreturn_t hpet_interrupt_handler(int irq, void *data)
 	struct hpet_dev *dev = (struct hpet_dev *)data;
 	struct clock_event_device *hevt = &dev->evt;
 
+	inc_irq_stat(hpet_timer_irqs);
 	if (!hevt->event_handler) {
 		printk(KERN_INFO "Spurious HPET timer interrupt on HPET timer %d\n",
 				dev->num);
arch/x86/kernel/time.c +1 -2
index fb5cc5e1..2098c56 100644
@@ -56,7 +56,7 @@ unsigned long profile_pc(struct pt_regs *regs)
 EXPORT_SYMBOL(profile_pc);
 
 /*
- * Default timer interrupt handler for PIT/HPET
+ * Default timer interrupt handler for PIT
  */
 static irqreturn_t timer_interrupt(int irq, void *dev_id)
 {
 
--

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