path: root/drivers
diff options
authorSaeed Mahameed <saeedm@mellanox.com>2019-02-11 18:04:17 +0200
committerDavid S. Miller <davem@davemloft.net>2019-02-12 12:26:21 -0500
commit29dded89e80e3fff61efb34f07a8a3fba3ea146d (patch)
treea67697092fbeeb7572439be103a21e2edfea1ad3 /drivers
parent87454b6edc1b0143fdb3d9853285477e95af74a4 (diff)
net/mlx4_en: Force CHECKSUM_NONE for short ethernet frames
When an ethernet frame is padded to meet the minimum ethernet frame size, the padding octets are not covered by the hardware checksum. Fortunately the padding octets are usually zero's, which don't affect checksum. However, it is not guaranteed. For example, switches might choose to make other use of these octets. This repeatedly causes kernel hardware checksum fault. Prior to the cited commit below, skb checksum was forced to be CHECKSUM_NONE when padding is detected. After it, we need to keep skb->csum updated. However, fixing up CHECKSUM_COMPLETE requires to verify and parse IP headers, it does not worth the effort as the packets are so small that CHECKSUM_COMPLETE has no significant advantage. Future work: when reporting checksum complete is not an option for IP non-TCP/UDP packets, we can actually fallback to report checksum unnecessary, by looking at cqe IPOK bit. Fixes: 88078d98d1bb ("net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends") Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Saeed Mahameed <saeedm@mellanox.com> Signed-off-by: Tariq Toukan <tariqt@mellanox.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
1 files changed, 20 insertions, 2 deletions
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index 9a0881cb7f51..6c01314e87b0 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -617,6 +617,8 @@ static int get_fixed_ipv6_csum(__wsum hw_checksum, struct sk_buff *skb,
+#define short_frame(size) ((size) <= ETH_ZLEN + ETH_FCS_LEN)
/* We reach this function only after checking that any of
* the (IPv4 | IPv6) bits are set in cqe->status.
@@ -624,9 +626,20 @@ static int check_csum(struct mlx4_cqe *cqe, struct sk_buff *skb, void *va,
netdev_features_t dev_features)
__wsum hw_checksum = 0;
+ void *hdr;
+ /* CQE csum doesn't cover padding octets in short ethernet
+ * frames. And the pad field is appended prior to calculating
+ * and appending the FCS field.
+ *
+ * Detecting these padded frames requires to verify and parse
+ * IP headers, so we simply force all those small frames to skip
+ * checksum complete.
+ */
+ if (short_frame(skb->len))
+ return -EINVAL;
- void *hdr = (u8 *)va + sizeof(struct ethhdr);
+ hdr = (u8 *)va + sizeof(struct ethhdr);
hw_checksum = csum_unfold((__force __sum16)cqe->checksum);
if (cqe->vlan_my_qpn & cpu_to_be32(MLX4_CQE_CVLAN_PRESENT_MASK) &&
@@ -819,6 +832,11 @@ xdp_drop_no_cnt:
skb_record_rx_queue(skb, cq_ring);
if (likely(dev->features & NETIF_F_RXCSUM)) {
+ /* TODO: For IP non TCP/UDP packets when csum complete is
+ * not an option (not supported or any other reason) we can
+ * actually check cqe IPOK status bit and report
+ */
if ((cqe->status & cpu_to_be16(MLX4_CQE_STATUS_TCP |
(cqe->status & cpu_to_be16(MLX4_CQE_STATUS_IPOK)) &&