Re: [PATCH v2] dma-buf: handle testing kthreads creation failure

[Christian König]

Am 22.05.24 um 20:33 schrieb T.J. Mercier:
> On Wed, May 22, 2024 at 11:14 AM Fedor Pchelkin <pchelkin@xxxxxxxxx> wrote:
> > kthread creation may possibly fail inside race_signal_callback(). In
> > such a case stop the already started threads, put the already taken
> > references to them and return with error code.
> >
> > Found by Linux Verification Center (linuxtesting.org).
> >
> > Fixes: 2989f6451084 ("dma-buf: Add selftests for dma-fence")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Fedor Pchelkin <pchelkin@xxxxxxxxx>
> Reviewed-by: T.J. Mercier <tjmercier@xxxxxxxxxx>

Just FYI: I've picked this one up and pushed it to drm-misc-fixes.

Regards,
Christian.

> > ---
> > v2: use kthread_stop_put() to actually put the last reference as
> >      T.J. Mercier noticed;
> >      link to v1: https://lore.kernel.org/lkml/20240522122326.696928-1-pchelkin@xxxxxxxxx/
> >
> >   drivers/dma-buf/st-dma-fence.c | 6 ++++++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/dma-buf/st-dma-fence.c b/drivers/dma-buf/st-dma-fence.c
> > index b7c6f7ea9e0c..6a1bfcd0cc21 100644
> > --- a/drivers/dma-buf/st-dma-fence.c
> > +++ b/drivers/dma-buf/st-dma-fence.c
> > @@ -540,6 +540,12 @@ static int race_signal_callback(void *arg)
> >                          t[i].before = pass;
> >                          t[i].task = kthread_run(thread_signal_callback, &t[i],
> >                                                  "dma-fence:%d", i);
> > +                       if (IS_ERR(t[i].task)) {
> > +                               ret = PTR_ERR(t[i].task);
> > +                               while (--i >= 0)
> > +                                       kthread_stop_put(t[i].task);
> > +                               return ret;
> > +                       }
> >                          get_task_struct(t[i].task);
> >                  }
> >
> > --
> > 2.39.2