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-rw-r--r--arch/i386/kernel/nmi.c42
1 files changed, 35 insertions, 7 deletions
diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c
index eaafe23..f5bc7e1 100644
--- a/arch/i386/kernel/nmi.c
+++ b/arch/i386/kernel/nmi.c
@@ -22,6 +22,7 @@
#include <linux/percpu.h>
#include <linux/dmi.h>
#include <linux/kprobes.h>
+#include <linux/cpumask.h>
#include <asm/smp.h>
#include <asm/nmi.h>
@@ -42,6 +43,8 @@ int nmi_watchdog_enabled;
static DEFINE_PER_CPU(unsigned long, perfctr_nmi_owner);
static DEFINE_PER_CPU(unsigned long, evntsel_nmi_owner[3]);
+static cpumask_t backtrace_mask = CPU_MASK_NONE;
+
/* this number is calculated from Intel's MSR_P4_CRU_ESCR5 register and it's
* offset from MSR_P4_BSU_ESCR0. It will be the max for all platforms (for now)
*/
@@ -867,14 +870,16 @@ static unsigned int
void touch_nmi_watchdog (void)
{
- int i;
+ if (nmi_watchdog > 0) {
+ unsigned cpu;
- /*
- * Just reset the alert counters, (other CPUs might be
- * spinning on locks we hold):
- */
- for_each_possible_cpu(i)
- alert_counter[i] = 0;
+ /*
+ * Just reset the alert counters, (other CPUs might be
+ * spinning on locks we hold):
+ */
+ for_each_present_cpu (cpu)
+ alert_counter[cpu] = 0;
+ }
/*
* Tickle the softlockup detector too:
@@ -907,6 +912,16 @@ __kprobes int nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)
touched = 1;
}
+ if (cpu_isset(cpu, backtrace_mask)) {
+ static DEFINE_SPINLOCK(lock); /* Serialise the printks */
+
+ spin_lock(&lock);
+ printk("NMI backtrace for cpu %d\n", cpu);
+ dump_stack();
+ spin_unlock(&lock);
+ cpu_clear(cpu, backtrace_mask);
+ }
+
sum = per_cpu(irq_stat, cpu).apic_timer_irqs;
/* if the apic timer isn't firing, this cpu isn't doing much */
@@ -1033,6 +1048,19 @@ int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
#endif
+void __trigger_all_cpu_backtrace(void)
+{
+ int i;
+
+ backtrace_mask = cpu_online_map;
+ /* Wait for up to 10 seconds for all CPUs to do the backtrace */
+ for (i = 0; i < 10 * 1000; i++) {
+ if (cpus_empty(backtrace_mask))
+ break;
+ mdelay(1);
+ }
+}
+
EXPORT_SYMBOL(nmi_active);
EXPORT_SYMBOL(nmi_watchdog);
EXPORT_SYMBOL(avail_to_resrv_perfctr_nmi);
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