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net/mlx5e: fix csum adjustments caused by RXFCS

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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 88078d98d1 "net: pskb_trim_rcsum()
and CHECKSUM_COMPLETE are friends"), the whole skb csum was thrown away,
so RXFCS changes were ignored.

Then before commit d55bef5059 ("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: 902a545904 ("net/mlx5e: When RXFCS is set, add FCS data into checksum calculation")
Reported-by: Paweł Staszewski <pstaszewski@itcare.pl>
Signed-off-by: Eric 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: Eran Ben Elisha <eranbe@mellanox.com>
Tested-By: Maria Pasechnik <mariap@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2018-10-30 00:57:25 -07:00 committed by David S. Miller
parent ff002269a4
commit d48051c5b8
1 changed files with 9 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
View File

@ -713,43 +713,15 @@ static inline void mlx5e_enable_ecn(struct mlx5e_rq *rq, struct sk_buff *skb)
rq->stats->ecn_mark += !!rc;
}
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 u8 get_ip_proto(struct sk_buff *skb, __be16 proto)
@ -797,8 +769,9 @@ static inline void mlx5e_handle_csum(struct net_device *netdev,
network_depth - ETH_HLEN,
skb->csum);
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);
stats->csum_complete++;
return;
}