From: Yicong Yang <yangyicong@hisilicon.com> Architecture's using perf events for hard lockup detection needs to convert the watchdog_thresh to the event's period, some architecture for example arm64 perform this conversion using the CPU's maximum frequency which will be acquired by cpufreq. However by the time the lockup detector's initialized the cpufreq driver may not be initialized, thus launch a watchdog with inaccurate period. Provide a function hardlockup_detector_perf_adjust_period() to allowing adjust the event period. Then architecture can update with more accurate period if cpufreq is initialized. Fixes: 94946f9eaac1 ("arm64: add hw_nmi_get_sample_period for preparation of lockup detector") Signed-off-by: Yicong Yang <yangyicong@hisilicon.com> Signed-off-by: Hongye Lin <linhongye@h-partners.com> Signed-off-by: Qi Xi <xiqi2@huawei.com> --- include/linux/nmi.h | 2 ++ kernel/watchdog_perf.c | 23 +++++++++++++++++++++++ 2 files changed, 25 insertions(+) diff --git a/include/linux/nmi.h b/include/linux/nmi.h index 43dd3a79fdf2..95805d31d28d 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -105,10 +105,12 @@ void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs); extern void hardlockup_detector_perf_stop(void); extern void hardlockup_detector_perf_restart(void); extern void hardlockup_detector_perf_cleanup(void); +extern void hardlockup_detector_perf_adjust_period(int cpu, u64 period); #else static inline void hardlockup_detector_perf_stop(void) { } static inline void hardlockup_detector_perf_restart(void) { } static inline void hardlockup_detector_perf_cleanup(void) { } +static inline void hardlockup_detector_perf_adjust_period(int cpu, u64 period) { } #endif void watchdog_hardlockup_stop(void); diff --git a/kernel/watchdog_perf.c b/kernel/watchdog_perf.c index 0052afe18b7f..989d30f80951 100644 --- a/kernel/watchdog_perf.c +++ b/kernel/watchdog_perf.c @@ -198,6 +198,29 @@ void hardlockup_detector_perf_cleanup(void) cpumask_clear(&dead_events_mask); } +/** + * hardlockup_detector_perf_adjust_period - Adjust the event period due + * to cpu frequency change + * @cpu: The CPU whose event period will be adjusted + * @period: The target period to be set + */ +void hardlockup_detector_perf_adjust_period(int cpu, u64 period) +{ + struct perf_event *event = per_cpu(watchdog_ev, cpu); + + if (!(watchdog_enabled & WATCHDOG_HARDLOCKUP_ENABLED)) + return; + + if (!event) + return; + + if (event->attr.sample_period == period) + return; + + if (perf_event_period(event, period)) + pr_err("failed to change period to %llu\n", period); +} + /** * hardlockup_detector_perf_stop - Globally stop watchdog events * -- 2.33.0