> Date: Sat, 17 Oct 2020 16:16:01 +0200
> From: Sebastien Marie <[email protected]>
>
> On Wed, Oct 14, 2020 at 08:58:04PM +0200, Mark Kettenis wrote:
> > > Date: Thu, 1 Oct 2020 09:09:50 +0200
> > > From: Sebastien Marie <[email protected]>
> > >
> > > Hi,
> > >
> > > Currently, when a process is calling kthread_stop(), it sets a flag
> > > asking the thread to stop, and enters in sleep mode, but the code
> > > doing the stop doesn't wakeup the caller of kthread_stop().
> > >
> > > The thread should also be unparked as else it will not seen the
> > > KTHREAD_SHOULDSTOP flag. it follows what Linux is doing.
> > >
> > > While here, I added some comments in the locking logic for park/unpark
> > > and stop.
> > >
> > > Comments or OK ?
> >
> > I don't think adding all those comments makes a lot of sense. This
> > uses a fairly standard tsleep/wakeup pattern and the some of the
> > comments really state the obvious.
>
> it was the way I did to audit the code and understand what it did.
>
> > Can you do a diff that just adds
> > the missing wakeup() and kthread_unpark() call?
>
> here a new diff.
ok kettenis@
> diff 4efbe95c75086b3a7b0074651bfa04fd58990a98 /home/semarie/repos/openbsd/src
> blob - fd797effc74d6eb4a172c81be8feac0ed168ec5d
> file + sys/dev/pci/drm/drm_linux.c
> --- sys/dev/pci/drm/drm_linux.c
> +++ sys/dev/pci/drm/drm_linux.c
> @@ -207,6 +217,7 @@ kthread_func(void *arg)
>
> ret = thread->func(thread->data);
> thread->flags |= KTHREAD_STOPPED;
> + wakeup(thread);
> kthread_exit(ret);
> }
>
> @@ -298,8 +327,9 @@ kthread_stop(struct proc *p)
>
> while ((thread->flags & KTHREAD_STOPPED) == 0) {
> thread->flags |= KTHREAD_SHOULDSTOP;
> + kthread_unpark(p);
> wake_up_process(thread->proc);
> tsleep_nsec(thread, PPAUSE, "stop", INFSLP);
> }
> LIST_REMOVE(thread, next);
>
>
> Thanks.
> --
> Sebastien Marie
>
