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Commit ac65fd70 authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
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net/mlx5e: fix csum adjustments caused by RXFCS 



[ Upstream commit d48051c5b8376038c2b287c3b1bd55b8d391d567 ]

As shown by Dmitris, we need to use csum_block_add() instead of csum_add()
when adding the FCS contribution to skb csum.

Before 4.18 (more exactly commit 88078d98d1bb "net: pskb_trim_rcsum()
and CHECKSUM_COMPLETE are friends"), the whole skb csum was thrown away,
so RXFCS changes were ignored.

Then before commit d55bef5059dd ("net: fix pskb_trim_rcsum_slow() with
odd trim offset") both mlx5 and pskb_trim_rcsum_slow() bugs were canceling
each other.

Now we fixed pskb_trim_rcsum_slow() we need to fix mlx5.

Note that this patch also rewrites mlx5e_get_fcs() to :

- Use skb_header_pointer() instead of reinventing it.
- Use __get_unaligned_cpu32() to avoid possible non aligned accesses
  as Dmitris pointed out.

Fixes: 902a545904c7 ("net/mlx5e: When RXFCS is set, add FCS data into checksum calculation")
Reported-by: default avatarPaweł Staszewski <pstaszewski@itcare.pl>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Eran Ben Elisha <eranbe@mellanox.com>
Cc: Saeed Mahameed <saeedm@mellanox.com>
Cc: Dimitris Michailidis <dmichail@google.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Paweł Staszewski <pstaszewski@itcare.pl>
Reviewed-by: default avatarEran Ben Elisha <eranbe@mellanox.com>
Tested-By: default avatarMaria Pasechnik <mariap@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 855cb69f

drivers/net/ethernet/mellanox/mlx5/core/en_rx.c

+9 −36
Original line number Diff line number Diff line
@@ -635,43 +635,15 @@ static inline bool is_first_ethertype_ip(struct sk_buff *skb) 
	return (ethertype == htons(ETH_P_IP) || ethertype == htons(ETH_P_IPV6));

}



static __be32 mlx5e_get_fcs(struct sk_buff *skb)

static u32 mlx5e_get_fcs(const struct sk_buff *skb)

{

	int last_frag_sz, bytes_in_prev, nr_frags;

	u8 *fcs_p1, *fcs_p2;

	skb_frag_t *last_frag;

	__be32 fcs_bytes;

	const void *fcs_bytes;

	u32 _fcs_bytes;



	if (!skb_is_nonlinear(skb))

		return *(__be32 *)(skb->data + skb->len - ETH_FCS_LEN);

	fcs_bytes = skb_header_pointer(skb, skb->len - ETH_FCS_LEN,

				       ETH_FCS_LEN, &_fcs_bytes);



	nr_frags = skb_shinfo(skb)->nr_frags;

	last_frag = &skb_shinfo(skb)->frags[nr_frags - 1];

	last_frag_sz = skb_frag_size(last_frag);



	/* If all FCS data is in last frag */

	if (last_frag_sz >= ETH_FCS_LEN)

		return *(__be32 *)(skb_frag_address(last_frag) +

				   last_frag_sz - ETH_FCS_LEN);



	fcs_p2 = (u8 *)skb_frag_address(last_frag);

	bytes_in_prev = ETH_FCS_LEN - last_frag_sz;



	/* Find where the other part of the FCS is - Linear or another frag */

	if (nr_frags == 1) {

		fcs_p1 = skb_tail_pointer(skb);

	} else {

		skb_frag_t *prev_frag = &skb_shinfo(skb)->frags[nr_frags - 2];



		fcs_p1 = skb_frag_address(prev_frag) +

			    skb_frag_size(prev_frag);

	}

	fcs_p1 -= bytes_in_prev;



	memcpy(&fcs_bytes, fcs_p1, bytes_in_prev);

	memcpy(((u8 *)&fcs_bytes) + bytes_in_prev, fcs_p2, last_frag_sz);



	return fcs_bytes;

	return __get_unaligned_cpu32(fcs_bytes);

}



static inline void mlx5e_handle_csum(struct net_device *netdev,
@@ -693,8 +665,9 @@ static inline void mlx5e_handle_csum(struct net_device *netdev, 
		skb->ip_summed = CHECKSUM_COMPLETE;

		skb->csum = csum_unfold((__force __sum16)cqe->check_sum);

		if (unlikely(netdev->features & NETIF_F_RXFCS))

			skb->csum = csum_add(skb->csum,

					     (__force __wsum)mlx5e_get_fcs(skb));

			skb->csum = csum_block_add(skb->csum,

						   (__force __wsum)mlx5e_get_fcs(skb),

						   skb->len - ETH_FCS_LEN);

		rq->stats.csum_complete++;

		return;

	}