Re: [PATCH next] vhost_task: after freeing vhost_task it should not be accessed in vhost_task_fn

Michael S. Tsirkin
2024-05-01T06:01:31Z

On Wed, May 01, 2024 at 08:15:44AM +0800, Hillf Danton wrote:
> On Tue, Apr 30, 2024 at 11:23:04AM -0500, Mike Christie wrote:
> > On 4/30/24 8:05 AM, Edward Adam Davis wrote:
> > > static int vhost_task_fn(void *data)
> > > {
> > > struct vhost_task *vtsk = data;
> > > @@ -51,7 +51,7 @@ static int vhost_task_fn(void *data)
> > > schedule();
> > > }
> > >
> > > - mutex_lock(&vtsk->exit_mutex);
> > > + mutex_lock(&exit_mutex);
> > > /*
> > > * If a vhost_task_stop and SIGKILL race, we can ignore the SIGKILL.
> > > * When the vhost layer has called vhost_task_stop it's already stopped
> > > @@ -62,7 +62,7 @@ static int vhost_task_fn(void *data)
> > > vtsk->handle_sigkill(vtsk->data);
> > > }
> > > complete(&vtsk->exited);
> > > - mutex_unlock(&vtsk->exit_mutex);
> > > + mutex_unlock(&exit_mutex);
> > >
> >
> > Edward, thanks for the patch. I think though I just needed to swap the
> > order of the calls above.
> >
> > Instead of:
> >
> > complete(&vtsk->exited);
> > mutex_unlock(&vtsk->exit_mutex);
> >
> > it should have been:
> >
> > mutex_unlock(&vtsk->exit_mutex);
> > complete(&vtsk->exited);
>
> JFYI Edward did it [1]
>
> [1] https://lore.kernel.org/lkml/tencent_546DA49414E876EEBECF2C78D26D242EE50A@qq.com/

and then it failed testing.

> >
> > If my analysis is correct, then Michael do you want me to resubmit a
> > patch on top of your vhost branch or resubmit the entire patchset?