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

BugLink: https://bugs.launchpad.net/bugs/1854842
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: 88078d98d1bb ("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>
(backported from commit 0aa1d18615c163f92935b806dcaff9157645233a)
[mruffell: file change mlx5e_update_sw_counters, context adjustments]
Signed-off-by: Matthew Ruffell <matthew.ruffell@canonical.com>
Acked-by: Connor Kuehl <connor.kuehl@canonical.com>
Acked-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index e39bb0ccb93dc006717e5242ef95ab06eb5f9514..b3c48515c91da0f12ab35083e7ae9f8b101021de 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -194,6 +194,8 @@ static void mlx5e_update_sw_counters(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;

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 323f2bd35bbe724c1ef0197db8da2b3ad68fa765..52f7dd0c02dd78909a816a00e9b2d840c01f60aa 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -661,17 +661,6 @@ 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;
@@ -682,6 +671,68 @@ 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,
@@ -729,10 +780,7 @@ 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, &rq->stats);
                rq->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 311d48b96e15a956b028d06c463f6103410b8f18..013a4feb1b35671995b3a2a5782f123a53b00c52 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
@@ -50,6 +50,8 @@ 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_tx) },
@@ -728,6 +730,8 @@ 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 66478c8c12ba21012166ebe5307c3c4ae0110e46..fe045e89c78b41a25efab35086ce83cf18fab732 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h
@@ -67,6 +67,8 @@ 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_tx;
@@ -151,6 +153,8 @@ 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;