[PATCH -rt 2/4] x86: return true for NMI handled

[Hiroshi Shimamoto]

From: Hiroshi Shimamoto <h-shimamoto@xxxxxxxxxxxxx>

NMI for show_regs causes unknown NMI when nmi_watchdog is local APIC mode.
Because lapic_wd_event() will fail due to still running perfctr.
If NMI is for show_regs, nmi_watchdog_tick() should return 1.

On x86_32, call irq_show_regs_callback() is moved to top of the
nmi_watchdog_tick() same as x86_64.

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@xxxxxxxxxxxxx>
---
 arch/x86/kernel/nmi_32.c |   10 +++++-----
 arch/x86/kernel/nmi_64.c |    9 +++++----
 include/linux/sched.h    |    2 +-
 3 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/nmi_32.c b/arch/x86/kernel/nmi_32.c
index da9deb3..d1f92ca 100644
--- a/arch/x86/kernel/nmi_32.c
+++ b/arch/x86/kernel/nmi_32.c
@@ -350,10 +350,10 @@ void nmi_show_all_regs(void)
 
 static DEFINE_RAW_SPINLOCK(nmi_print_lock);
 
-notrace void irq_show_regs_callback(int cpu, struct pt_regs *regs)
+notrace int irq_show_regs_callback(int cpu, struct pt_regs *regs)
 {
 	if (!nmi_show_regs[cpu])
-		return;
+		return 0;
 
 	nmi_show_regs[cpu] = 0;
 	spin_lock(&nmi_print_lock);
@@ -362,6 +362,7 @@ notrace void irq_show_regs_callback(int cpu, struct pt_regs *regs)
 		per_cpu(irq_stat, cpu).apic_timer_irqs);
 	show_regs(regs);
 	spin_unlock(&nmi_print_lock);
+	return 1;
 }
 
 notrace __kprobes int
@@ -376,8 +377,9 @@ nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)
 	unsigned int sum;
 	int touched = 0;
 	int cpu = smp_processor_id();
-	int rc=0;
+	int rc;
 
+	rc = irq_show_regs_callback(cpu, regs);
 	__profile_tick(CPU_PROFILING, regs);
 
 	/* check for other users first */
@@ -404,8 +406,6 @@ nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)
 	sum = per_cpu(irq_stat, cpu).apic_timer_irqs +
 		per_cpu(irq_stat, cpu).irq0_irqs;
 
-	irq_show_regs_callback(cpu, regs);
-
 	/* if the apic timer isn't firing, this cpu isn't doing much */
 	/* if the none of the timers isn't firing, this cpu isn't doing much */
 	if (!touched && last_irq_sums[cpu] == sum) {
diff --git a/arch/x86/kernel/nmi_64.c b/arch/x86/kernel/nmi_64.c
index 5d3073c..afc0317 100644
--- a/arch/x86/kernel/nmi_64.c
+++ b/arch/x86/kernel/nmi_64.c
@@ -340,10 +340,10 @@ void nmi_show_all_regs(void)
 
 static DEFINE_RAW_SPINLOCK(nmi_print_lock);
 
-notrace void irq_show_regs_callback(int cpu, struct pt_regs *regs)
+notrace int irq_show_regs_callback(int cpu, struct pt_regs *regs)
 {
 	if (!nmi_show_regs[cpu])
-		return;
+		return 0;
 
 	nmi_show_regs[cpu] = 0;
 	spin_lock(&nmi_print_lock);
@@ -351,6 +351,7 @@ notrace void irq_show_regs_callback(int cpu, struct pt_regs *regs)
 	printk(KERN_WARNING "apic_timer_irqs: %d\n", read_pda(apic_timer_irqs));
 	show_regs(regs);
 	spin_unlock(&nmi_print_lock);
+	return 1;
 }
 
 notrace int __kprobes
@@ -359,9 +360,9 @@ nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)
 	int sum;
 	int touched = 0;
 	int cpu = smp_processor_id();
-	int rc = 0;
+	int rc;
 
-	irq_show_regs_callback(cpu, regs);
+	rc = irq_show_regs_callback(cpu, regs);
 	__profile_tick(CPU_PROFILING, regs);
 
 	/* check for other users first */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4176f87..a37200a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -292,7 +292,7 @@ static inline void show_state(void)
 }
 
 extern void show_regs(struct pt_regs *);
-extern void irq_show_regs_callback(int cpu, struct pt_regs *regs);
+extern int irq_show_regs_callback(int cpu, struct pt_regs *regs);
 
 /*
  * TASK is a pointer to the task whose backtrace we want to see (or NULL for current
-- 
1.5.4.1

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