linux-kernel - 答复: [PATCH][v2] watchdog/hardlockup: reassign last

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Date:   Fri, 22 Nov 2019 10:39:15 +0000
From:   "Li,Rongqing" <lirongqing@...du.com>
To:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "sergey.senozhatsky.work@...il.com" 
        <sergey.senozhatsky.work@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "Kan.liang@...el.com" <Kan.liang@...el.com>
Subject: 答复: [PATCH][v2] watchdog/hardlockup: reassign last_timestamp when enable nmi event

Ping

Thanks
-RongQing

> -----邮件原件-----
> 发件人: Li,Rongqing
> 发送时间: 2019年11月7日 18:54
> 收件人: Li,Rongqing <lirongqing@...du.com>; akpm@...ux-foundation.org;
> sergey.senozhatsky.work@...il.com; linux-kernel@...r.kernel.org;
> tglx@...utronix.de; Kan.liang@...el.com
> 主题: 答复: [PATCH][v2] watchdog/hardlockup: reassign last_timestamp when
> enable nmi event
> 
> Ping
> 
> Thanks
> 
> -Li
> 
> > -----邮件原件-----
> > 发件人: linux-kernel-owner@...r.kernel.org
> > [mailto:linux-kernel-owner@...r.kernel.org] 代表 Li RongQing
> > 发送时间: 2019年10月15日 14:34
> > 收件人: akpm@...ux-foundation.org; sergey.senozhatsky.work@...il.com;
> > linux-kernel@...r.kernel.org; tglx@...utronix.de; Kan.liang@...el.com
> > 主题: [PATCH][v2] watchdog/hardlockup: reassign last_timestamp when
> > enable nmi event
> >
> > 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 <lirongqing@...du.com>
> > Signed-off-by: Zhang Yu <zhangyu31@...du.com>
> > ---
> >
> > v1-->v2: make it be able to be compiled on no
> > v1-->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