Re: [RFC PATCH net-next 01/12] vhost_net: introduce helper to initialize tx iov iter

Jason Wang
2018-05-22T12:26:48Z

On 2018年05月22日 00:24, Jesse Brandeburg wrote:
> Hi Jason, a few nits.
>
> On Mon, 21 May 2018 17:04:22 +0800 Jason wrote:
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>> drivers/vhost/net.c | 34 +++++++++++++++++++++++-----------
>> 1 file changed, 23 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
>> index c4b49fc..15d191a 100644
>> --- a/drivers/vhost/net.c
>> +++ b/drivers/vhost/net.c
>> @@ -459,6 +459,26 @@ static bool vhost_exceeds_maxpend(struct vhost_net *net)
>> min_t(unsigned int, VHOST_MAX_PEND, vq->num >> 2);
>> }
>>
>> +static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,
>> + size_t hdr_size, int out)
>> +{
>> + /* Skip header. TODO: support TSO. */
>> + size_t len = iov_length(vq->iov, out);
>> +
>> + iov_iter_init(iter, WRITE, vq->iov, out, len);
>> + iov_iter_advance(iter, hdr_size);
>> + /* Sanity check */
>> + if (!iov_iter_count(iter)) {
>> + vq_err(vq, "Unexpected header len for TX: "
>> + "%zd expected %zd\n",
>> + len, hdr_size);
> ok, it was like this before, but please unwrap the string in " ", there
> should be no line breaks in string declarations and they are allowed to
> go over 80 characters.

Ok.

>
>> + return -EFAULT;
>> + }
>> + len = iov_iter_count(iter);
>> +
>> + return len;
>> +}
>> +
>> /* Expects to be always run from workqueue - which acts as
>> * read-size critical section for our kind of RCU. */
>> static void handle_tx(struct vhost_net *net)
>> @@ -521,18 +541,10 @@ static void handle_tx(struct vhost_net *net)
>> "out %d, int %d\n", out, in);
>> break;
>> }
>> - /* Skip header. TODO: support TSO. */
>> - len = iov_length(vq->iov, out);
>> - iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
>> - iov_iter_advance(&msg.msg_iter, hdr_size);
>> - /* Sanity check */
>> - if (!msg_data_left(&msg)) {
>> - vq_err(vq, "Unexpected header len for TX: "
>> - "%zd expected %zd\n",
>> - len, hdr_size);
>> +
>> + len = init_iov_iter(vq, &msg.msg_iter, hdr_size, out);
>> + if (len < 0)
> len is declared as size_t, which is unsigned, and can never be
> negative. I'm pretty sure this is a bug.

Yes, let me fix it in next version.

Thanks

>
>
>> break;
>> - }
>> - len = msg_data_left(&msg);
>>
>> zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
>> && !vhost_exceeds_maxpend(net)