Messages in this thread | | | Date | Sun, 29 May 2022 01:29:32 -0300 | From | Geraldo Nascimento <> | Subject | Re: [PATCH] workqueue: missing NOT while checking if Workqueue is offline |
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On Sat, May 28, 2022 at 10:25:55PM -0300, Geraldo Nascimento wrote: > On Sat, May 28, 2022 at 05:07:08PM -0300, Geraldo Nascimento wrote: > > Greetings, > > > > Hi, again, >
And again, Hi!
Doing my due dilligence, it seems.
> > This is a one-character patch but very important as the kernel workqueue > > __cancel_work_timer will cancel active work
It won't cancel important work, seems it's just a WARN_ON but it's very annoying. My understanding was the NOT was needed to call __flush_work() before kthreads are spawned. During early boot, as the comment says, before workqueue_init() fires.
There's a bug report at https://gitlab.freedesktop.org/drm/amd/-/issues/1898 and Felix Kuehling is right that this bug is only triggered when you try to use amdkfd ( and the Kconfigs that implies) without HSA_AMD_SVM configured.
It makes sense to me that NOT operator is missing however, since in the warning I was coming from _cancel_work_timer() to __flush_work(), something that should not be done?
I would like very much to hear the opinion of the maintainers!
Thanks, Geraldo Nascimento
>> without the NOT operator > > added. > > > > During early boot wq_online is false so with the NOT added it will evaluate > > to true. Conversely, after boot is done, workqueue > > I meant wq_online. After boot, wq_online will evaluate to true, current > code might as well have an if (true) there. I hurried up the patch > because if I'm right this is a major show stopper to drivers that make > use of cancel_work_timer(). I hit it through amdgpu in conjuction with amdkfd. > > > is now true and we want > > it to evaluate to false because otherwise it will cancel important work. > > > > Signed-off-by: Geraldo Nascimento <geraldogabriel@gmail.com> > > > > --- workqueue.c 2022-05-28 16:54:12.024176123 -0300 > > +++ workqueue.c 2022-05-28 16:54:37.698176135 -0300 > > @@ -3158,7 +3158,7 @@ static bool __cancel_work_timer(struct w > > * This allows canceling during early boot. We know that @work > > * isn't executing. > > */ > > - if (wq_online) > > + if (!wq_online) > > __flush_work(work, true); > > > > clear_work_data(work);
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