diff options
Diffstat (limited to 'arch/i386/kernel/nmi.c')
-rw-r--r-- | arch/i386/kernel/nmi.c | 40 |
1 files changed, 37 insertions, 3 deletions
diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c index 0178457db72..d661703ac1c 100644 --- a/arch/i386/kernel/nmi.c +++ b/arch/i386/kernel/nmi.c @@ -15,7 +15,6 @@ #include <linux/config.h> #include <linux/mm.h> -#include <linux/irq.h> #include <linux/delay.h> #include <linux/bootmem.h> #include <linux/smp_lock.h> @@ -101,16 +100,44 @@ int nmi_active; (P4_CCCR_OVF_PMI0|P4_CCCR_THRESHOLD(15)|P4_CCCR_COMPLEMENT| \ P4_CCCR_COMPARE|P4_CCCR_REQUIRED|P4_CCCR_ESCR_SELECT(4)|P4_CCCR_ENABLE) +#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 + * CPUs during the test make them busy. + */ +static __init void nmi_cpu_busy(void *data) +{ + volatile int *endflag = data; + local_irq_enable(); + /* Intentionally don't use cpu_relax here. This is + to make sure that the performance counter really ticks, + even if there is a simulator or similar that catches the + 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(); +} +#endif + static int __init check_nmi_watchdog(void) { - unsigned int prev_nmi_count[NR_CPUS]; + volatile int endflag = 0; + unsigned int *prev_nmi_count; int cpu; if (nmi_watchdog == NMI_NONE) return 0; + prev_nmi_count = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL); + if (!prev_nmi_count) + return -1; + printk(KERN_INFO "Testing NMI watchdog ... "); + if (nmi_watchdog == NMI_LOCAL_APIC) + smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 0); + for (cpu = 0; cpu < NR_CPUS; cpu++) prev_nmi_count[cpu] = per_cpu(irq_stat, cpu).__nmi_count; local_irq_enable(); @@ -124,12 +151,18 @@ static int __init check_nmi_watchdog(void) continue; #endif if (nmi_count(cpu) - prev_nmi_count[cpu] <= 5) { - printk("CPU#%d: NMI appears to be stuck!\n", cpu); + endflag = 1; + printk("CPU#%d: NMI appears to be stuck (%d->%d)!\n", + cpu, + prev_nmi_count[cpu], + nmi_count(cpu)); nmi_active = 0; lapic_nmi_owner &= ~LAPIC_NMI_WATCHDOG; + kfree(prev_nmi_count); return -1; } } + endflag = 1; printk("OK.\n"); /* now that we know it works we can reduce NMI frequency to @@ -137,6 +170,7 @@ static int __init check_nmi_watchdog(void) if (nmi_watchdog == NMI_LOCAL_APIC) nmi_hz = 1; + kfree(prev_nmi_count); return 0; } /* This needs to happen later in boot so counters are working */ |