Messages in this thread | | | Date | Wed, 20 Oct 2021 12:38:49 +0200 | From | Vincent Whitchurch <> | Subject | Re: [PATCH 2/2] i2c: virtio: fix completion handling |
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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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