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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>
This commit is contained in:
Thomas Gleixner 2017-09-12 21:37:18 +02:00 committed by Ingo Molnar
parent 091549858e
commit 178b9f7a36
2 changed files with 43 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
include/linux/nmi.h
View File

@ -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);

37
kernel/watchdog_hld.c
View File

@ -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;
}