Merge branch 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc

[sfrench/cifs-2.6.git] / arch / i386 / kernel / nmi.c

diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c
index eaafe233a5da83f4abbb2c17e670b8a46fa4edaa..1a6f8bb8881ce72fa99909914beb70141b4a519f 100644 (file)
--- 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)
  */
@@ -192,6 +195,8 @@ static __cpuinit inline int nmi_known_cpu(void)
        return 0;
 }
 
+static int endflag __initdata = 0;
+
 #ifdef CONFIG_SMP
 /* The performance counters used by NMI_LOCAL_APIC don't trigger when
  * the CPU is idle. To make sure the NMI watchdog really ticks on all
@@ -199,7 +204,6 @@ static __cpuinit inline int nmi_known_cpu(void)
  */
 static __init void nmi_cpu_busy(void *data)
 {
-       volatile int *endflag = data;
        local_irq_enable_in_hardirq();
        /* Intentionally don't use cpu_relax here. This is
           to make sure that the performance counter really ticks,
@@ -207,14 +211,13 @@ static __init void nmi_cpu_busy(void *data)
           pause instruction. On a real HT machine this is fine because
           all other CPUs are busy with "useless" delay loops and don't
           care if they get somewhat less cycles. */
-       while (*endflag == 0)
-               barrier();
+       while (endflag == 0)
+               mb();
 }
 #endif
 
 static int __init check_nmi_watchdog(void)
 {
-       volatile int endflag = 0;
        unsigned int *prev_nmi_count;
        int cpu;
 
@@ -307,13 +310,7 @@ static int __init setup_nmi_watchdog(char *str)
 
        if ((nmi >= NMI_INVALID) || (nmi < NMI_NONE))
                return 0;
-       /*
-        * If any other x86 CPU has a local APIC, then
-        * please test the NMI stuff there and send me the
-        * missing bits. Right now Intel P6/P4 and AMD K7 only.
-        */
-       if ((nmi == NMI_LOCAL_APIC) && (nmi_known_cpu() == 0))
-               return 0;  /* no lapic support */
+
        nmi_watchdog = nmi;
        return 1;
 }
@@ -867,14 +864,16 @@ 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 +906,16 @@ __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 +1042,19 @@ 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);