Messages in this thread | | | Date | Thu, 16 Sep 2021 10:36:10 +0200 | From | Petr Mladek <> | Subject | Re: [PATCH 3/5] kernel/watchdog: adapt the watchdog_hld interface for async model |
| |
On Thu 2021-09-16 10:29:05, Petr Mladek wrote: > On Wed 2021-09-15 11:51:01, Pingfan Liu wrote: > > When lockup_detector_init()->watchdog_nmi_probe(), PMU may be not ready > > yet. E.g. on arm64, PMU is not ready until > > device_initcall(armv8_pmu_driver_init). And it is deeply integrated > > with the driver model and cpuhp. Hence it is hard to push this > > initialization before smp_init(). > > > > But it is easy to take an opposite approach by enabling watchdog_hld to > > get the capability of PMU async. > > This is another cryptic description. I have probably got it after > looking at the 5th patch (was not Cc :-( > > > The async model is achieved by introducing an extra parameter notifier > > of watchdog_nmi_probe(). > > I would say that the code is horrible and looks too complex. > > What about simply calling watchdog_nmi_probe() and > lockup_detector_setup() once again when watchdog_nmi_probe() > failed in lockup_detector_init()? > > Or do not call lockup_detector_init() at all in > kernel_init_freeable() when PMU is not ready yet.
BTW: It is an overkill to create your own kthread just to run some code just once. And you implemeted it a wrong way. The kthread must wait in a loop until someone else stop it and read the exit code.
The easiest solution is to queue a work into system_wq for this.
I was not Cc for the 5th patch, so I write it here.
Best Regards, Petr
| |