}
__setup("nmi_watchdog=", setup_nmi_watchdog);
-#ifdef CONFIG_SYSCTL
-/*
- * proc handler for /proc/sys/kernel/nmi_watchdog
- */
-int nmi_watchdog_enabled;
-
-int proc_nmi_enabled(struct ctl_table *table, int write,
- void __user *buffer, size_t *length, loff_t *ppos)
-{
- int cpu;
-
- if (!write) {
- struct perf_event *event;
- for_each_online_cpu(cpu) {
- event = per_cpu(nmi_watchdog_ev, cpu);
- if (event->state > PERF_EVENT_STATE_OFF) {
- nmi_watchdog_enabled = 1;
- break;
- }
- }
- proc_dointvec(table, write, buffer, length, ppos);
- return 0;
- }
-
- if (per_cpu(nmi_watchdog_ev, smp_processor_id()) == NULL) {
- nmi_watchdog_enabled = 0;
- proc_dointvec(table, write, buffer, length, ppos);
- printk("NMI watchdog failed configuration, can not be enabled\n");
- return 0;
- }
-
- touch_all_nmi_watchdog();
- proc_dointvec(table, write, buffer, length, ppos);
- if (nmi_watchdog_enabled)
- for_each_online_cpu(cpu)
- perf_event_enable(per_cpu(nmi_watchdog_ev, cpu));
- else
- for_each_online_cpu(cpu)
- perf_event_disable(per_cpu(nmi_watchdog_ev, cpu));
- return 0;
-}
-
-#endif /* CONFIG_SYSCTL */
-
struct perf_event_attr wd_attr = {
.type = PERF_TYPE_HARDWARE,
.config = PERF_COUNT_HW_CPU_CYCLES,
return;
}
+static int enable_nmi_watchdog(int cpu)
+{
+ struct perf_event *event;
+
+ event = per_cpu(nmi_watchdog_ev, cpu);
+ if (event && event->state > PERF_EVENT_STATE_OFF)
+ return 0;
+
+ if (event == NULL) {
+ /* Try to register using hardware perf events first */
+ wd_attr.sample_period = hw_nmi_get_sample_period();
+ event = perf_event_create_kernel_counter(&wd_attr, cpu, -1, wd_overflow);
+ if (IS_ERR(event)) {
+ wd_attr.type = PERF_TYPE_SOFTWARE;
+ event = perf_event_create_kernel_counter(&wd_attr, cpu, -1, wd_overflow);
+ if (IS_ERR(event)) {
+ printk(KERN_ERR "nmi watchdog failed to create perf event on %i: %p\n", cpu, event);
+ return -1;
+ }
+ }
+ per_cpu(nmi_watchdog_ev, cpu) = event;
+ }
+ perf_event_enable(per_cpu(nmi_watchdog_ev, cpu));
+ return 0;
+}
+
+static void disable_nmi_watchdog(int cpu)
+{
+ struct perf_event *event;
+
+ event = per_cpu(nmi_watchdog_ev, cpu);
+ if (event) {
+ perf_event_disable(per_cpu(nmi_watchdog_ev, cpu));
+ per_cpu(nmi_watchdog_ev, cpu) = NULL;
+ perf_event_release_kernel(event);
+ }
+}
+
+#ifdef CONFIG_SYSCTL
+/*
+ * proc handler for /proc/sys/kernel/nmi_watchdog
+ */
+int nmi_watchdog_enabled;
+
+int proc_nmi_enabled(struct ctl_table *table, int write,
+ void __user *buffer, size_t *length, loff_t *ppos)
+{
+ int cpu;
+
+ if (!write) {
+ struct perf_event *event;
+ for_each_online_cpu(cpu) {
+ event = per_cpu(nmi_watchdog_ev, cpu);
+ if (event && event->state > PERF_EVENT_STATE_OFF) {
+ nmi_watchdog_enabled = 1;
+ break;
+ }
+ }
+ proc_dointvec(table, write, buffer, length, ppos);
+ return 0;
+ }
+
+ touch_all_nmi_watchdog();
+ proc_dointvec(table, write, buffer, length, ppos);
+ if (nmi_watchdog_enabled) {
+ for_each_online_cpu(cpu)
+ if (enable_nmi_watchdog(cpu)) {
+ printk("NMI watchdog failed configuration, "
+ " can not be enabled\n");
+ }
+ } else {
+ for_each_online_cpu(cpu)
+ disable_nmi_watchdog(cpu);
+ }
+ return 0;
+}
+
+#endif /* CONFIG_SYSCTL */
+
/*
* Create/destroy watchdog threads as CPUs come and go:
*/
cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
int hotcpu = (unsigned long)hcpu;
- struct perf_event *event;
switch (action) {
case CPU_UP_PREPARE:
break;
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
- /* originally wanted the below chunk to be in CPU_UP_PREPARE, but caps is unpriv for non-CPU0 */
- wd_attr.sample_period = hw_nmi_get_sample_period();
- event = perf_event_create_kernel_counter(&wd_attr, hotcpu, -1, wd_overflow);
- if (IS_ERR(event)) {
- wd_attr.type = PERF_TYPE_SOFTWARE;
- event = perf_event_create_kernel_counter(&wd_attr, hotcpu, -1, wd_overflow);
- if (IS_ERR(event)) {
- printk(KERN_ERR "nmi watchdog failed to create perf event on %i: %p\n", hotcpu, event);
- return NOTIFY_BAD;
- }
- }
- per_cpu(nmi_watchdog_ev, hotcpu) = event;
- perf_event_enable(per_cpu(nmi_watchdog_ev, hotcpu));
+ if (enable_nmi_watchdog(hotcpu))
+ return NOTIFY_BAD;
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
- perf_event_disable(per_cpu(nmi_watchdog_ev, hotcpu));
+ disable_nmi_watchdog(hotcpu);
case CPU_DEAD:
case CPU_DEAD_FROZEN:
- event = per_cpu(nmi_watchdog_ev, hotcpu);
- per_cpu(nmi_watchdog_ev, hotcpu) = NULL;
- perf_event_release_kernel(event);
break;
#endif /* CONFIG_HOTPLUG_CPU */
}