[Intel-wired-lan] [PATCH net] xdp, net: fix for construct skb by xdp inside xsk zc rx
Xuan Zhuo
xuanzhuo at linux.alibaba.com
Thu Jun 17 14:18:09 UTC 2021
On Thu, 17 Jun 2021 15:09:48 +0200, Maciej Fijalkowski <maciej.fijalkowski at intel.com> wrote:
> 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 at linux.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.
I saw that the previous patch was put into net-queue, I don't know whether to
merge it into the current patch, so I posted this patch, I hope someone can tell
me how to deal with this situation.
>
> 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.
I have this question too.
Thanks
>
> 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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