> > > > while (!virtqueue_get_buf(vi->cvq, &tmp) &&
> > > > - !virtqueue_is_broken(vi->cvq))
> > > > + !virtqueue_is_broken(vi->cvq)) {
> > > > + if (timeout)
> > > > + timeout--;
> > > This is not really a timeout, just a loop counter. 200 iterations could
> > > be a very short time on reasonable H/W. I guess this avoid the soft
> > > lockup, but possibly (likely?) breaks the functionality when we need to
> > > loop for some non negligible time.
> > >
> > > I fear we need a more complex solution, as mentioned by Micheal in the
> > > thread you quoted.
> >
> > Got it. I also look forward to the more complex solution to this problem.
>
> Can we add a device capability (new feature bit) such as ctrq_wait_timeout
> to get a reasonable timeout？
The usual solution to this is include/linux/iopoll.h. If you can sleep
read_poll_timeout() otherwise read_poll_timeout_atomic().
Andrew
