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Message-ID: <20210617130948.GA20486@ranger.igk.intel.com>
Date: Thu, 17 Jun 2021 15:09:48 +0200
From: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc: netdev@...r.kernel.org, bpf@...r.kernel.org,
Jesse Brandeburg <jesse.brandeburg@...el.com>,
Tony Nguyen <anthony.l.nguyen@...el.com>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Giuseppe Cavallaro <peppe.cavallaro@...com>,
Alexandre Torgue <alexandre.torgue@...s.st.com>,
Jose Abreu <joabreu@...opsys.com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
Björn Töpel <bjorn@...nel.org>,
Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
Krzysztof Kazimierczak <krzysztof.kazimierczak@...el.com>,
Ong Boon Leong <boon.leong.ong@...el.com>,
intel-wired-lan@...ts.osuosl.org,
linux-stm32@...md-mailman.stormreply.com,
linux-arm-kernel@...ts.infradead.org, maximmi@...dia.com
Subject: Re: [PATCH net] xdp, net: fix for construct skb by xdp inside xsk zc
rx
On Tue, Jun 15, 2021 at 11:37:19AM +0800, Xuan Zhuo wrote:
> When each driver supports xsk rx, if the received buff returns XDP_PASS
> after run xdp prog, it must construct skb based on xdp. This patch
> extracts this logic into a public function xdp_construct_skb().
>
> There is a bug in the original logic. When constructing skb, we should
> copy the meta information to skb and then use __skb_pull() to correct
> the data.
>
> Fixes: 0a714186d3c0f ("i40e: add AF_XDP zero-copy Rx support")
> Fixes: 2d4238f556972 ("ice: Add support for AF_XDP")
> Fixes: bba2556efad66 ("net: stmmac: Enable RX via AF_XDP zero-copy")
> Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
> ---
>
> This patch depends on the previous patch:
> [PATCH net] ixgbe: xsk: fix for metasize when construct skb by xdp_buff
That doesn't make much sense if you ask me, I'd rather squash the patch
mentioned above to this one.
Also, I wanted to introduce such function to the kernel for a long time
but I always head in the back of my head mlx5's AF_XDP ZC implementation
which I'm not sure if it can adjust to something like Intel drivers are
doing.
Maxim? :)
>
> drivers/net/ethernet/intel/i40e/i40e_xsk.c | 16 +---------
> drivers/net/ethernet/intel/ice/ice_xsk.c | 12 +-------
> drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 14 +--------
> .../net/ethernet/stmicro/stmmac/stmmac_main.c | 23 +-------------
> include/net/xdp.h | 30 +++++++++++++++++++
> 5 files changed, 34 insertions(+), 61 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
> index 68f177a86403..81b0f44eedda 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
> @@ -246,23 +246,9 @@ bool i40e_alloc_rx_buffers_zc(struct i40e_ring *rx_ring, u16 count)
> static struct sk_buff *i40e_construct_skb_zc(struct i40e_ring *rx_ring,
> struct xdp_buff *xdp)
> {
> - unsigned int metasize = xdp->data - xdp->data_meta;
> - unsigned int datasize = xdp->data_end - xdp->data;
> struct sk_buff *skb;
>
> - /* allocate a skb to store the frags */
> - skb = __napi_alloc_skb(&rx_ring->q_vector->napi,
> - xdp->data_end - xdp->data_hard_start,
> - GFP_ATOMIC | __GFP_NOWARN);
> - if (unlikely(!skb))
> - goto out;
> -
> - skb_reserve(skb, xdp->data - xdp->data_hard_start);
> - memcpy(__skb_put(skb, datasize), xdp->data, datasize);
> - if (metasize)
> - skb_metadata_set(skb, metasize);
> -
> -out:
> + skb = xdp_construct_skb(xdp, &rx_ring->q_vector->napi);
> xsk_buff_free(xdp);
> return skb;
> }
> diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c
> index a1f89ea3c2bd..f95e1adcebda 100644
> --- a/drivers/net/ethernet/intel/ice/ice_xsk.c
> +++ b/drivers/net/ethernet/intel/ice/ice_xsk.c
> @@ -430,22 +430,12 @@ static void ice_bump_ntc(struct ice_ring *rx_ring)
> static struct sk_buff *
> ice_construct_skb_zc(struct ice_ring *rx_ring, struct ice_rx_buf *rx_buf)
> {
> - unsigned int metasize = rx_buf->xdp->data - rx_buf->xdp->data_meta;
> - unsigned int datasize = rx_buf->xdp->data_end - rx_buf->xdp->data;
> - unsigned int datasize_hard = rx_buf->xdp->data_end -
> - rx_buf->xdp->data_hard_start;
> struct sk_buff *skb;
>
> - skb = __napi_alloc_skb(&rx_ring->q_vector->napi, datasize_hard,
> - GFP_ATOMIC | __GFP_NOWARN);
> + skb = xdp_construct_skb(rx_buf->xdp, &rx_ring->q_vector->napi);
> if (unlikely(!skb))
> return NULL;
>
> - skb_reserve(skb, rx_buf->xdp->data - rx_buf->xdp->data_hard_start);
> - memcpy(__skb_put(skb, datasize), rx_buf->xdp->data, datasize);
> - if (metasize)
> - skb_metadata_set(skb, metasize);
> -
> xsk_buff_free(rx_buf->xdp);
> rx_buf->xdp = NULL;
> return skb;
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> index ee88107fa57a..123945832c96 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
> @@ -203,24 +203,12 @@ bool ixgbe_alloc_rx_buffers_zc(struct ixgbe_ring *rx_ring, u16 count)
> static struct sk_buff *ixgbe_construct_skb_zc(struct ixgbe_ring *rx_ring,
> struct ixgbe_rx_buffer *bi)
> {
> - unsigned int metasize = bi->xdp->data - bi->xdp->data_meta;
> - unsigned int datasize = bi->xdp->data_end - bi->xdp->data_meta;
> struct sk_buff *skb;
>
> - /* allocate a skb to store the frags */
> - skb = __napi_alloc_skb(&rx_ring->q_vector->napi,
> - bi->xdp->data_end - bi->xdp->data_hard_start,
> - GFP_ATOMIC | __GFP_NOWARN);
> + skb = xdp_construct_skb(bi->xdp, &rx_ring->q_vector->napi);
> if (unlikely(!skb))
> return NULL;
>
> - skb_reserve(skb, bi->xdp->data_meta - bi->xdp->data_hard_start);
> - memcpy(__skb_put(skb, datasize), bi->xdp->data_meta, datasize);
> - if (metasize) {
> - __skb_pull(skb, metasize);
> - skb_metadata_set(skb, metasize);
> - }
> -
> xsk_buff_free(bi->xdp);
> bi->xdp = NULL;
> return skb;
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index c87202cbd3d6..143ac1edb876 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -4729,27 +4729,6 @@ static void stmmac_finalize_xdp_rx(struct stmmac_priv *priv,
> xdp_do_flush();
> }
>
> -static struct sk_buff *stmmac_construct_skb_zc(struct stmmac_channel *ch,
> - struct xdp_buff *xdp)
> -{
> - unsigned int metasize = xdp->data - xdp->data_meta;
> - unsigned int datasize = xdp->data_end - xdp->data;
> - struct sk_buff *skb;
> -
> - skb = __napi_alloc_skb(&ch->rxtx_napi,
> - xdp->data_end - xdp->data_hard_start,
> - GFP_ATOMIC | __GFP_NOWARN);
> - if (unlikely(!skb))
> - return NULL;
> -
> - skb_reserve(skb, xdp->data - xdp->data_hard_start);
> - memcpy(__skb_put(skb, datasize), xdp->data, datasize);
> - if (metasize)
> - skb_metadata_set(skb, metasize);
> -
> - return skb;
> -}
> -
> static void stmmac_dispatch_skb_zc(struct stmmac_priv *priv, u32 queue,
> struct dma_desc *p, struct dma_desc *np,
> struct xdp_buff *xdp)
> @@ -4761,7 +4740,7 @@ static void stmmac_dispatch_skb_zc(struct stmmac_priv *priv, u32 queue,
> struct sk_buff *skb;
> u32 hash;
>
> - skb = stmmac_construct_skb_zc(ch, xdp);
> + skb = xdp_construct_skb(xdp, &ch->rxtx_napi);
> if (!skb) {
> priv->dev->stats.rx_dropped++;
> return;
> diff --git a/include/net/xdp.h b/include/net/xdp.h
> index a5bc214a49d9..561e21eaf718 100644
> --- a/include/net/xdp.h
> +++ b/include/net/xdp.h
> @@ -95,6 +95,36 @@ xdp_prepare_buff(struct xdp_buff *xdp, unsigned char *hard_start,
> xdp->data_meta = meta_valid ? data : data + 1;
> }
>
> +static __always_inline struct sk_buff *
> +xdp_construct_skb(struct xdp_buff *xdp, struct napi_struct *napi)
> +{
> + unsigned int metasize;
> + unsigned int datasize;
> + unsigned int headroom;
> + struct sk_buff *skb;
> + unsigned int len;
> +
> + /* this include metasize */
> + datasize = xdp->data_end - xdp->data_meta;
> + metasize = xdp->data - xdp->data_meta;
> + headroom = xdp->data_meta - xdp->data_hard_start;
> + len = xdp->data_end - xdp->data_hard_start;
> +
> + /* allocate a skb to store the frags */
> + skb = __napi_alloc_skb(napi, len, GFP_ATOMIC | __GFP_NOWARN);
> + if (unlikely(!skb))
> + return NULL;
> +
> + skb_reserve(skb, headroom);
> + memcpy(__skb_put(skb, datasize), xdp->data_meta, datasize);
> + if (metasize) {
> + __skb_pull(skb, metasize);
> + skb_metadata_set(skb, metasize);
> + }
> +
> + return skb;
> +}
> +
> /* Reserve memory area at end-of data area.
> *
> * This macro reserves tailroom in the XDP buffer by limiting the
> --
> 2.31.0
>
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