lkml.org 
[lkml]   [2021]   [Oct]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/2] i2c: virtio: fix completion handling
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?

\
 
 \ /
  Last update: 2021-10-20 12:39    [W:0.147 / U:0.052 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site