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

[Jason Wang]

On 2018å05æ22æ 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@xxxxxxxxxx>
> > ---
> >   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)