Re: [PATCH net 9/9] virtio-net: XDP support for small buffers

From: John Fastabend
Date: Tue Jan 03 2017 - 11:41:03 EST


On 17-01-02 10:16 PM, Jason Wang wrote:
>
>
> On 2017å01æ03æ 06:43, John Fastabend wrote:
>> On 16-12-23 06:37 AM, Jason Wang wrote:
>>> Commit f600b6905015 ("virtio_net: Add XDP support") leaves the case of
>>> small receive buffer untouched. This will confuse the user who want to
>>> set XDP but use small buffers. Other than forbid XDP in small buffer
>>> mode, let's make it work. XDP then can only work at skb->data since
>>> virtio-net create skbs during refill, this is sub optimal which could
>>> be optimized in the future.
>>>
>>> Cc: John Fastabend <john.r.fastabend@xxxxxxxxx>
>>> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
>>> ---
>>> drivers/net/virtio_net.c | 112 ++++++++++++++++++++++++++++++++++++-----------
>>> 1 file changed, 87 insertions(+), 25 deletions(-)
>>>
>> Hi Jason,
>>
>> I was doing some more testing on this what do you think about doing this
>> so that free_unused_bufs() handles the buffer free with dev_kfree_skb()
>> instead of put_page in small receive mode. Seems more correct to me.
>>
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 783e842..27ff76c 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -1898,6 +1898,10 @@ static void free_receive_page_frags(struct virtnet_info
>> *vi)
>>
>> static bool is_xdp_queue(struct virtnet_info *vi, int q)
>> {
>> + /* For small receive mode always use kfree_skb variants */
>> + if (!vi->mergeable_rx_bufs)
>> + return false;
>> +
>> if (q < (vi->curr_queue_pairs - vi->xdp_queue_pairs))
>> return false;
>> else if (q < vi->curr_queue_pairs)
>>
>>
>> patch is untested just spotted doing code review.
>>
>> Thanks,
>> John
>
> We probably need a better name for this function.
>
> Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
>

How about is_xdp_raw_buffer_queue()?

I'll submit a proper patch today.