Commit 178b9f7a authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarDon 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: default avatarIngo Molnar <mingo@kernel.org>
parent 09154985

include/linux/nmi.h

+6 −2
Original line number Diff line number Diff line
@@ -93,13 +93,17 @@ 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)

static inline int hardlockup_detector_perf_init(void) { return -ENODEV; }

static inline void arch_touch_nmi_watchdog(void) {}

# else

static inline int hardlockup_detector_perf_init(void) { return 0; }

# endif

#endif

kernel/watchdog_hld.c

+37 −0
Original line number Diff line number Diff line
@@ -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;

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE