Re: [PATCH net-next 11/12] net: hns3: do not allocate linear data for fraglist skb

[tanhuazhong]

On 2019/10/17 1:18, Jakub Kicinski wrote:
> On Wed, 16 Oct 2019 15:17:10 +0800, Huazhong Tan wrote:
> > From: Yunsheng Lin <linyunsheng@xxxxxxxxxx>
> >
> > Currently, napi_alloc_skb() is used to allocate skb for fraglist
> > when the head skb is not enough to hold the remaining data, and
> > the remaining data is added to the frags part of the fraglist skb,
> > leaving the linear part unused.
> >
> > So this patch passes length of 0 to allocate fraglist skb with
> > zero size of linear data.
> >
> > Fixes: 81ae0e0491f3 ("net: hns3: Add skb chain when num of RX buf exceeds MAX_SKB_FRAGS")
> > Signed-off-by: Yunsheng Lin <linyunsheng@xxxxxxxxxx>
> > Signed-off-by: Huazhong Tan <tanhuazhong@xxxxxxxxxx>
>
> Is this really a fix? I just wastes memory, right?

It is a minor optimizations. This fix tag is a mistake.
Thanks.

> > diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
> > index 6172eb2..14111af 100644
> > --- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
> > +++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
> > @@ -2866,8 +2866,7 @@ static int hns3_add_frag(struct hns3_enet_ring *ring, struct hns3_desc *desc,
> >   			return -ENXIO;
> >   
> >   		if (unlikely(ring->frag_num >= MAX_SKB_FRAGS)) {
> > -			new_skb = napi_alloc_skb(&ring->tqp_vector->napi,
> > -						 HNS3_RX_HEAD_SIZE);
> > +			new_skb = napi_alloc_skb(&ring->tqp_vector->napi, 0);
> >   			if (unlikely(!new_skb)) {
> >   				hns3_rl_err(ring_to_netdev(ring),
> >   					    "alloc rx fraglist skb fail\n");
>
>
> .