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authorThomas Gleixner <tglx@linutronix.de>2017-09-12 21:37:18 +0200
committerIngo Molnar <mingo@kernel.org>2017-09-14 11:41:08 +0200
commit178b9f7a36d2c74a38274b66dd89f53611298a19 (patch)
tree6ea60b3626a552baa282502b62cd19b4429889bf
parent091549858ed881e5f3054374af4f5b1cac681d50 (diff)
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watchdog/hardlockup/perf: Implement init time perf validation
The watchdog tries to create perf events even after it figured out that perf is not functional or the requested event is not supported. That's braindead as this can be done once at init time and if not supported the NMI watchdog can be turned off unconditonally. Implement the perf hardlockup detector functionality for that. This creates a new event create function, which will replace the unholy mess of the existing one in later patches. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Link: http://lkml.kernel.org/r/20170912194148.019090547@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--include/linux/nmi.h8
-rw-r--r--kernel/watchdog_hld.c37
2 files changed, 43 insertions, 2 deletions
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index eee255bc0fd6..72c62a809e92 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -93,14 +93,18 @@ extern void hardlockup_detector_perf_stop(void);
extern void hardlockup_detector_perf_restart(void);
extern void hardlockup_detector_perf_disable(void);
extern void hardlockup_detector_perf_cleanup(void);
+extern int hardlockup_detector_perf_init(void);
#else
static inline void hardlockup_detector_perf_stop(void) { }
static inline void hardlockup_detector_perf_restart(void) { }
static inline void hardlockup_detector_perf_disable(void) { }
static inline void hardlockup_detector_perf_cleanup(void) { }
-#if !defined(CONFIG_HAVE_NMI_WATCHDOG)
+# if !defined(CONFIG_HAVE_NMI_WATCHDOG)
+static inline int hardlockup_detector_perf_init(void) { return -ENODEV; }
static inline void arch_touch_nmi_watchdog(void) {}
-#endif
+# else
+static inline int hardlockup_detector_perf_init(void) { return 0; }
+# endif
#endif
void watchdog_nmi_reconfigure(bool run);
diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c
index 0aa191ee3d51..f7e752e6e9b4 100644
--- a/kernel/watchdog_hld.c
+++ b/kernel/watchdog_hld.c
@@ -238,6 +238,27 @@ out:
return 0;
}
+static int hardlockup_detector_event_create(void)
+{
+ unsigned int cpu = smp_processor_id();
+ struct perf_event_attr *wd_attr;
+ struct perf_event *evt;
+
+ wd_attr = &wd_hw_attr;
+ wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
+
+ /* Try to register using hardware perf events */
+ evt = perf_event_create_kernel_counter(wd_attr, cpu, NULL,
+ watchdog_overflow_callback, NULL);
+ if (IS_ERR(evt)) {
+ pr_info("Perf event create on CPU %d failed with %ld\n", cpu,
+ PTR_ERR(evt));
+ return PTR_ERR(evt);
+ }
+ this_cpu_write(watchdog_ev, evt);
+ return 0;
+}
+
/**
* hardlockup_detector_perf_disable - Disable the local event
*/
@@ -315,3 +336,19 @@ void __init hardlockup_detector_perf_restart(void)
perf_event_enable(event);
}
}
+
+/**
+ * hardlockup_detector_perf_init - Probe whether NMI event is available at all
+ */
+int __init hardlockup_detector_perf_init(void)
+{
+ int ret = hardlockup_detector_event_create();
+
+ if (ret) {
+ pr_info("Perf NMI watchdog permanetely disabled\n");
+ } else {
+ perf_event_release_kernel(this_cpu_read(watchdog_ev));
+ this_cpu_write(watchdog_ev, NULL);
+ }
+ return ret;
+}