[dpdk-stable] [PATCH] vdpa/mlx5: fix configuration mutex cleanup

[David Marchand]

On Thu, Jan 7, 2021 at 7:09 PM Maxime Coquelin
<maxime.coquelin at redhat.com> wrote:
> On 1/6/21 7:43 AM, Matan Azrad wrote:
> > When the vDPA device is closed, the driver polling thread is canceled.
> > The polling thread locks the configuration mutex while it polls the CQs.
> >
> > When the cancellation happens, it may terminate the thread inside the
> > critical section what remains the configuration mutex locked.
> >
> > After device close, the driver may be configured again, in this case,
> > for example, when the first queue state is updated, the driver tries to
> > lock the mutex again and deadlock appears.
> >
> > Initialize the mutex after the polling thread cancellation.
> >
> > Fixes: 99abbd62c272 ("vdpa/mlx5: fix queue update synchronization")
> > Cc: stable at dpdk.org
> >
> > Signed-off-by: Matan Azrad <matan at nvidia.com>
> > Acked-by: Xueming Li <xuemingl at nvidia.com>
> > ---
> >  drivers/vdpa/mlx5/mlx5_vdpa.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/vdpa/mlx5/mlx5_vdpa.c b/drivers/vdpa/mlx5/mlx5_vdpa.c
> > index b64f364..0b2f1ab 100644
> > --- a/drivers/vdpa/mlx5/mlx5_vdpa.c
> > +++ b/drivers/vdpa/mlx5/mlx5_vdpa.c
> > @@ -295,6 +295,8 @@
> >       }
> >       priv->configured = 0;
> >       priv->vid = 0;
> > +     /* The mutex may stay locked after event thread cancel - initiate it. */
> > +     pthread_mutex_init(&priv->vq_config_lock, NULL);
> >       DRV_LOG(INFO, "vDPA device %d was closed.", vid);
> >       return ret;
> >  }
> >
>
> I wonder if it would be possible and cleaner to disable cancellation on
> the thread while the mutex is held?

+1

-- 
David Marchand