On Thu, Aug 03, 2017 at 03:17:59PM +0000, Wang, Wei W wrote:
> On Thursday, August 3, 2017 10:23 PM, Michael S. Tsirkin wrote:
> > On Thu, Aug 03, 2017 at 02:38:17PM +0800, Wei Wang wrote:
> > > +static void send_one_sg(struct virtio_balloon *vb, struct virtqueue *vq,
> > > + void *addr, uint32_t size)
> > > +{
> > > + struct scatterlist sg;
> > > + unsigned int len;
> > > +
> > > + sg_init_one(&sg, addr, size);
> > > + while (unlikely(virtqueue_add_inbuf(vq, &sg, 1, vb, GFP_KERNEL)
> > > + == -ENOSPC)) {
> > > + /*
> > > + * It is uncommon to see the vq is full, because the sg is sent
> > > + * one by one and the device is able to handle it in time. But
> > > + * if that happens, we kick and wait for an entry is released.
> >
> > is released -> to get used.
> >
> > > + */
> > > + virtqueue_kick(vq);
> > > + while (!virtqueue_get_buf(vq, &len) &&
> > > + !virtqueue_is_broken(vq))
> > > + cpu_relax();
> >
> > Please rework to use wait_event in that case too.
>
> For the balloon page case here, it is fine to use wait_event. But for the free page
> case, I think it might not be suitable because the mm lock is being held.
>
> Best,
> Wei
You will have to find a way to drop the lock and restart from where you
stopped then.
--
MST
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