Virtualization - Oct 2021 - [PATCH 2/2] i2c: virtio: fix completion handling

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))
                        complete(&vi->completion);
        }

Since we already know which is the last one, we can also check at this
point if buffers for all other requests are received or not.

-- 
viresh

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 ?

>                          complete(&vi->completion);
>          }
>
> Since we already know which is the last one, we can also check at this
> point if buffers for all other requests are received or not.
>