last_timestamp is not initialized and is zero after boot, or stop to forward when nmi watchdog is disabled; and false positives still is possible when restart NMI timer after stopping 120 seconds
so reassign last_timestamp always when enable nmi event Fixes: 7edaeb6841df ("kernel/watchdog: Prevent false positives with turbo modes") Signed-off-by: Li RongQing <lirongq...@baidu.com> Signed-off-by: Zhang Yu <zhangy...@baidu.com> --- v1-->v2: make it be able to be compiled on no CONFIG_HARDLOCKUP_CHECK_TIMESTAMP platform kernel/watchdog_hld.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c index 247bf0b1582c..f14d18280387 100644 --- a/kernel/watchdog_hld.c +++ b/kernel/watchdog_hld.c @@ -91,11 +91,24 @@ static bool watchdog_check_timestamp(void) __this_cpu_write(last_timestamp, now); return true; } + +static void watchdog_touch_timestamp(int cpu) +{ + + ktime_t now = ktime_get_mono_fast_ns(); + + per_cpu(last_timestamp, cpu) = now; +} #else static inline bool watchdog_check_timestamp(void) { return true; } + +static void watchdog_touch_timestamp(int cpu) +{ + +} #endif static struct perf_event_attr wd_hw_attr = { @@ -196,6 +209,7 @@ void hardlockup_detector_perf_enable(void) if (!atomic_fetch_inc(&watchdog_cpus)) pr_info("Enabled. Permanently consumes one hw-PMU counter.\n"); + watchdog_touch_timestamp(smp_processor_id()); perf_event_enable(this_cpu_read(watchdog_ev)); } @@ -274,8 +288,10 @@ void __init hardlockup_detector_perf_restart(void) for_each_online_cpu(cpu) { struct perf_event *event = per_cpu(watchdog_ev, cpu); - if (event) + if (event) { + watchdog_touch_timestamp(cpu); perf_event_enable(event); + } } } -- 2.16.2