[Intel-wired-lan] [PATCH net] xdp, net: fix for construct skb by xdp inside xsk zc rx

[Intel-wired-lan] [PATCH net] xdp, net: fix for construct skb by xdp inside xsk zc rx

[Xuan Zhuo]

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@linux.alibaba.com>
---

This patch depends on the previous patch:
    [PATCH net] ixgbe: xsk: fix for metasize when construct skb by xdp_buff

 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

[Intel-wired-lan] [PATCH net] xdp, net: fix for construct skb by xdp inside xsk zc rx

[Maciej Fijalkowski]

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@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.

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
> 

[Intel-wired-lan] [PATCH net] xdp, net: fix for construct skb by xdp inside xsk zc rx

[Xuan Zhuo]

On Thu, 17 Jun 2021 15:09:48 +0200, Maciej Fijalkowski <maciej.fijalkowski@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@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
> >

[Intel-wired-lan] [PATCH net] xdp, net: fix for construct skb by xdp inside xsk zc rx

[Nguyen, Anthony L]

On Thu, 2021-06-17 at 22:18 +0800, Xuan Zhuo wrote:
> 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@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.

The previous patch was to the Intel Wired LAN tree since it was just
ixgbe driver. I will drop this from Intel Wired LAN tree since it
hasn't been submitted to netdev and with these changes it makes more
sense as a single squashed patch.

> > 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
> > >