Messages in this thread | | | Date | Mon, 7 Aug 2023 15:54:04 +0200 | From | Petr Mladek <> | Subject | Re: [PATCH] watchdog/hardlockup: set watchdog_hardlockup_warned to true as early as possible |
| |
On Sun 2023-08-06 10:52:57, Liu Song wrote: > > 在 2023/8/6 01:17, Andrew Morton 写道: > > When resending, please tell us some more about the effects of the > > change. Presumably there are circumstances in which excess output is > > produced? If so, describe these circumstances and the observed > > effects. > > Hi, > > I haven't found duplicate warnings in the real environment. > > However, considering that when system occurs hard lockup is basically > abnormal, it > > seems more reasonable to set "watchdog_hardlockup_warned" to ture, rather > than > > waiting for all kinds of information to be printed.
I believe that this is not needed.
watchdog_hardlockup_check(cpu, regs) is called on a CPU periodically. There are two callers:
+ buddy detector checks the particular CPU when the solflockup's hrtimer callback is called. See watchdog_hardlockup_kick() in watchdog_timer_fn().
+ perf detector checks the particular CPU from a perf callback, see watchdog_overflow_callback().
Neither timer nor perf callbacks might be nested. They are naturally serialized on a given CPU. So, races are not possible in this case.
Best Regards, Petr
| |