net/mlx5e: Rx, Fixup skb checksum for packets with tail padding

When an ethernet frame with ip payload is padded, the padding octets are
not covered by the hardware checksum.

Prior to the cited commit, skb checksum was forced to be CHECKSUM_NONE
when padding is detected. After it, the kernel will try to trim the
padding bytes and subtract their checksum from skb->csum.

In this patch we fixup skb->csum for any ip packet with tail padding of
any size, if any padding found.
FCS case is just one special case of this general purpose patch, hence,
it is removed.

Fixes: 7943627623eb ("net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends"),
Cc: Eric Dumazet <edumazet@google.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 91af48344743b5dfc672413fd607b05dc7f41896..0e254de23f3d7310e429fa1591a69d75a1f4ec3a 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -712,17 +712,6 @@ static inline void mlx5e_enable_ecn(struct mlx5e_rq *rq, struct sk_buff *skb)
        rq->stats->ecn_mark += !!rc;
 }
 
-static u32 mlx5e_get_fcs(const struct sk_buff *skb)
-{
-       const void *fcs_bytes;
-       u32 _fcs_bytes;
-
-       fcs_bytes = skb_header_pointer(skb, skb->len - ETH_FCS_LEN,
-                                      ETH_FCS_LEN, &_fcs_bytes);
-
-       return __get_unaligned_cpu32(fcs_bytes);
-}
-
 static u8 get_ip_proto(struct sk_buff *skb, int network_depth, __be16 proto)
 {
        void *ip_p = skb->data + network_depth;
@@ -733,6 +722,68 @@ static u8 get_ip_proto(struct sk_buff *skb, int network_depth, __be16 proto)
 
 #define short_frame(size) ((size) <= ETH_ZLEN + ETH_FCS_LEN)
 
+#define MAX_PADDING 8
+
+static void
+tail_padding_csum_slow(struct sk_buff *skb, int offset, int len,
+                      struct mlx5e_rq_stats *stats)
+{
+       stats->csum_complete_tail_slow++;
+       skb->csum = csum_block_add(skb->csum,
+                                  skb_checksum(skb, offset, len, 0),
+                                  offset);
+}
+
+static void
+tail_padding_csum(struct sk_buff *skb, int offset,
+                 struct mlx5e_rq_stats *stats)
+{
+       u8 tail_padding[MAX_PADDING];
+       int len = skb->len - offset;
+       void *tail;
+
+       if (unlikely(len > MAX_PADDING)) {
+               tail_padding_csum_slow(skb, offset, len, stats);
+               return;
+       }
+
+       tail = skb_header_pointer(skb, offset, len, tail_padding);
+       if (unlikely(!tail)) {
+               tail_padding_csum_slow(skb, offset, len, stats);
+               return;
+       }
+
+       stats->csum_complete_tail++;
+       skb->csum = csum_block_add(skb->csum, csum_partial(tail, len, 0), offset);
+}
+
+static void
+mlx5e_skb_padding_csum(struct sk_buff *skb, int network_depth, __be16 proto,
+                      struct mlx5e_rq_stats *stats)
+{
+       struct ipv6hdr *ip6;
+       struct iphdr   *ip4;
+       int pkt_len;
+
+       switch (proto) {
+       case htons(ETH_P_IP):
+               ip4 = (struct iphdr *)(skb->data + network_depth);
+               pkt_len = network_depth + ntohs(ip4->tot_len);
+               break;
+       case htons(ETH_P_IPV6):
+               ip6 = (struct ipv6hdr *)(skb->data + network_depth);
+               pkt_len = network_depth + sizeof(*ip6) + ntohs(ip6->payload_len);
+               break;
+       default:
+               return;
+       }
+
+       if (likely(pkt_len >= skb->len))
+               return;
+
+       tail_padding_csum(skb, pkt_len, stats);
+}
+
 static inline void mlx5e_handle_csum(struct net_device *netdev,
                                     struct mlx5_cqe64 *cqe,
                                     struct mlx5e_rq *rq,
@@ -781,10 +832,8 @@ static inline void mlx5e_handle_csum(struct net_device *netdev,
                        skb->csum = csum_partial(skb->data + ETH_HLEN,
                                                 network_depth - ETH_HLEN,
                                                 skb->csum);
-               if (unlikely(netdev->features & NETIF_F_RXFCS))
-                       skb->csum = csum_block_add(skb->csum,
-                                                  (__force __wsum)mlx5e_get_fcs(skb),
-                                                  skb->len - ETH_FCS_LEN);
+
+               mlx5e_skb_padding_csum(skb, network_depth, proto, stats);
                stats->csum_complete++;
                return;
        }

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
index 1a78e05cbba8168d919bfd45af3378becd3c9b68..b75aa8b8bf04eac8cac464c0c8550013154f6267 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
@@ -59,6 +59,8 @@ static const struct counter_desc sw_stats_desc[] = {
        { MLX5E_DECLARE_STAT(struct mlx5e_sw_stats, rx_csum_unnecessary) },
        { MLX5E_DECLARE_STAT(struct mlx5e_sw_stats, rx_csum_none) },
        { MLX5E_DECLARE_STAT(struct mlx5e_sw_stats, rx_csum_complete) },
+       { MLX5E_DECLARE_STAT(struct mlx5e_sw_stats, rx_csum_complete_tail) },
+       { MLX5E_DECLARE_STAT(struct mlx5e_sw_stats, rx_csum_complete_tail_slow) },
        { MLX5E_DECLARE_STAT(struct mlx5e_sw_stats, rx_csum_unnecessary_inner) },
        { MLX5E_DECLARE_STAT(struct mlx5e_sw_stats, rx_xdp_drop) },
        { MLX5E_DECLARE_STAT(struct mlx5e_sw_stats, rx_xdp_redirect) },
@@ -151,6 +153,8 @@ static void mlx5e_grp_sw_update_stats(struct mlx5e_priv *priv)
                s->rx_removed_vlan_packets += rq_stats->removed_vlan_packets;
                s->rx_csum_none += rq_stats->csum_none;
                s->rx_csum_complete += rq_stats->csum_complete;
+               s->rx_csum_complete_tail += rq_stats->csum_complete_tail;
+               s->rx_csum_complete_tail_slow += rq_stats->csum_complete_tail_slow;
                s->rx_csum_unnecessary += rq_stats->csum_unnecessary;
                s->rx_csum_unnecessary_inner += rq_stats->csum_unnecessary_inner;
                s->rx_xdp_drop     += rq_stats->xdp_drop;
@@ -1190,6 +1194,8 @@ static const struct counter_desc rq_stats_desc[] = {
        { MLX5E_DECLARE_RX_STAT(struct mlx5e_rq_stats, packets) },
        { MLX5E_DECLARE_RX_STAT(struct mlx5e_rq_stats, bytes) },
        { MLX5E_DECLARE_RX_STAT(struct mlx5e_rq_stats, csum_complete) },
+       { MLX5E_DECLARE_RX_STAT(struct mlx5e_rq_stats, csum_complete_tail) },
+       { MLX5E_DECLARE_RX_STAT(struct mlx5e_rq_stats, csum_complete_tail_slow) },
        { MLX5E_DECLARE_RX_STAT(struct mlx5e_rq_stats, csum_unnecessary) },
        { MLX5E_DECLARE_RX_STAT(struct mlx5e_rq_stats, csum_unnecessary_inner) },
        { MLX5E_DECLARE_RX_STAT(struct mlx5e_rq_stats, csum_none) },

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h
index 4640d4f986f8c6495bc5c94cf22217fb59a64b34..16c3b785f282b109e9b2bc54bd4c136095be9b3f 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h
@@ -71,6 +71,8 @@ struct mlx5e_sw_stats {
        u64 rx_csum_unnecessary;
        u64 rx_csum_none;
        u64 rx_csum_complete;
+       u64 rx_csum_complete_tail;
+       u64 rx_csum_complete_tail_slow;
        u64 rx_csum_unnecessary_inner;
        u64 rx_xdp_drop;
        u64 rx_xdp_redirect;
@@ -181,6 +183,8 @@ struct mlx5e_rq_stats {
        u64 packets;
        u64 bytes;
        u64 csum_complete;
+       u64 csum_complete_tail;
+       u64 csum_complete_tail_slow;
        u64 csum_unnecessary;
        u64 csum_unnecessary_inner;
        u64 csum_none;