linux-kernel - Re: [PATCH 2/2] i2c: virtio: fix completion handling

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Date:   Wed, 20 Oct 2021 16:54:57 +0800
From:   Jie Deng <jie.deng@...el.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>
Cc:     wsa@...nel.org, virtualization@...ts.linux-foundation.org,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel@...s.com
Subject: Re: [PATCH 2/2] i2c: virtio: fix completion handling


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.
>