On Wed, Oct 20, 2021 at 11:17:21AM +0200, Viresh Kumar wrote:
> On 20-10-21, 16:54, Jie Deng wrote:
> >
> > On 2021/10/19 16:22, Viresh Kumar wrote:
> > > On 19-10-21, 09:46, Vincent Whitchurch wrote:
> > > > static void virtio_i2c_msg_done(struct virtqueue *vq)
> > > > {
> > > > - struct virtio_i2c *vi = vq->vdev->priv;
> > > > + struct virtio_i2c_req *req;
> > > > + unsigned int len;
> > > > - complete(&vi->completion);
> > > > + while ((req = virtqueue_get_buf(vq, &len)))
> > > > + complete(&req->completion);
> > > Instead of adding a completion for each request and using only the
> > > last one, maybe we can do this instead here:
> > >
> > > while ((req = virtqueue_get_buf(vq, &len))) {
> > > if (req->out_hdr.flags ==
> > > cpu_to_le32(VIRTIO_I2C_FLAGS_FAIL_NEXT))
> >
> >
> > Is this for the last one check ? For the last one, this bit should be
> > cleared, right ?
>
> Oops, you are right. This should be `!=` instead. Thanks.
I don't quite understand how that would be safe since
virtqueue_add_sgs() can fail after a few iterations and all queued
request buffers can have FAIL_NEXT set. In such a case, we would end up
waiting forever with your proposed change, wouldn't we?
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