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Message-ID: <612ebe4548da_6b87208fa@john-XPS-13-9370.notmuch>
Date: Tue, 31 Aug 2021 16:41:57 -0700
From: John Fastabend <john.fastabend@...il.com>
To: Lorenzo Bianconi <lorenzo@...nel.org>, bpf@...r.kernel.org,
netdev@...r.kernel.org
Cc: lorenzo.bianconi@...hat.com, davem@...emloft.net, kuba@...nel.org,
ast@...nel.org, daniel@...earbox.net, shayagr@...zon.com,
john.fastabend@...il.com, dsahern@...nel.org, brouer@...hat.com,
echaudro@...hat.com, jasowang@...hat.com,
alexander.duyck@...il.com, saeed@...nel.org,
maciej.fijalkowski@...el.com, magnus.karlsson@...el.com,
tirthendu.sarkar@...el.com, toke@...hat.com
Subject: RE: [PATCH v12 bpf-next 06/18] net: marvell: rely on
xdp_update_skb_shared_info utility routine
Lorenzo Bianconi wrote:
> Rely on xdp_update_skb_shared_info routine in order to avoid
> resetting frags array in skb_shared_info structure building
> the skb in mvneta_swbm_build_skb(). Frags array is expected to
> be initialized by the receiving driver building the xdp_buff
> and here we just need to update memory metadata.
>
> Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
> ---
Acked-by: John Fastabend <john.fastabend@...il.com>
> drivers/net/ethernet/marvell/mvneta.c | 35 +++++++++++++++------------
> 1 file changed, 20 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
> index cbf614d6b993..b996eb49d813 100644
> --- a/drivers/net/ethernet/marvell/mvneta.c
> +++ b/drivers/net/ethernet/marvell/mvneta.c
> @@ -2304,11 +2304,19 @@ mvneta_swbm_add_rx_fragment(struct mvneta_port *pp,
> skb_frag_size_set(frag, data_len);
> __skb_frag_set_page(frag, page);
>
> - if (!xdp_buff_is_mb(xdp))
> + if (!xdp_buff_is_mb(xdp)) {
> + sinfo->xdp_frags_size = *size;
> xdp_buff_set_mb(xdp);
> + }
> + if (page_is_pfmemalloc(page))
> + xdp_buff_set_frag_pfmemalloc(xdp);
> } else {
> page_pool_put_full_page(rxq->page_pool, page, true);
> }
> +
> + /* last fragment */
> + if (len == *size)
> + sinfo->xdp_frags_tsize = sinfo->nr_frags * PAGE_SIZE;
> *size -= len;
> }
>
> @@ -2316,13 +2324,18 @@ static struct sk_buff *
> mvneta_swbm_build_skb(struct mvneta_port *pp, struct page_pool *pool,
> struct xdp_buff *xdp, u32 desc_status)
> {
> - struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);
> + unsigned int size, truesize;
> struct sk_buff *skb;
> u8 num_frags;
> - int i;
>
> - if (unlikely(xdp_buff_is_mb(xdp)))
> + if (unlikely(xdp_buff_is_mb(xdp))) {
Just curious does the mvneta hardware support header split? If we
get to that point then we can drop the unlikely.
> + struct skb_shared_info *sinfo;
> +
> + sinfo = xdp_get_shared_info_from_buff(xdp);
> + truesize = sinfo->xdp_frags_tsize;
> + size = sinfo->xdp_frags_size;
> num_frags = sinfo->nr_frags;
> + }
>
> skb = build_skb(xdp->data_hard_start, PAGE_SIZE);
> if (!skb)
> @@ -2334,18 +2347,10 @@ mvneta_swbm_build_skb(struct mvneta_port *pp, struct page_pool *pool,
> skb_put(skb, xdp->data_end - xdp->data);
> skb->ip_summed = mvneta_rx_csum(pp, desc_status);
>
> - if (likely(!xdp_buff_is_mb(xdp)))
> - goto out;
> -
> - for (i = 0; i < num_frags; i++) {
> - skb_frag_t *frag = &sinfo->frags[i];
> -
> - skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
> - skb_frag_page(frag), skb_frag_off(frag),
> - skb_frag_size(frag), PAGE_SIZE);
> - }
> + if (unlikely(xdp_buff_is_mb(xdp)))
> + xdp_update_skb_shared_info(skb, num_frags, size, truesize,
> + xdp_buff_is_frag_pfmemalloc(xdp));
>
> -out:
> return skb;
> }
>
> --
> 2.31.1
>
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