[PATCH] bnx2x: fix checksum validation

[Eric Dumazet <eric.dumazet@gmail.com>]

From: Eric Dumazet <edumazet@google.com>

bnx2x driver incorrectly sets ip_summed to CHECKSUM_UNNECESSARY on
encapsulated segments. TCP stack happily accepts frames with bad
checksums, if they are inside a GRE or IPIP encapsulation.

Our understanding is that if no IP or L4 csum validation was done by the
hardware, we should leave ip_summed as is (CHECKSUM_NONE), since
hardware doesn't provide CHECKSUM_COMPLETE support in its cqe.

Then, if IP/L4 checksumming was done by the hardware, set
CHECKSUM_UNNECESSARY if no error was flagged.

Patch based on findings and analysis from Robert Evans

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Eilon Greenstein <eilong@broadcom.com>
Cc: Yaniv Rosner <yanivr@broadcom.com>
Cc: Merav Sicron <meravs@broadcom.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Robert Evans <evansr@google.com>
Cc: Willem de Bruijn <willemb@google.com>
---
 drivers/net/ethernet/broadcom/bnx2x/bnx2x.h     |   15 -------
 drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c |   27 ++++++++++----
 2 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h b/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
index e30e2a2..7de8241 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
@@ -747,21 +747,6 @@ struct bnx2x_fastpath {
 
 #define ETH_RX_ERROR_FALGS		ETH_FAST_PATH_RX_CQE_PHY_DECODE_ERR_FLG
 
-#define BNX2X_IP_CSUM_ERR(cqe) \
-			(!((cqe)->fast_path_cqe.status_flags & \
-			   ETH_FAST_PATH_RX_CQE_IP_XSUM_NO_VALIDATION_FLG) && \
-			 ((cqe)->fast_path_cqe.type_error_flags & \
-			  ETH_FAST_PATH_RX_CQE_IP_BAD_XSUM_FLG))
-
-#define BNX2X_L4_CSUM_ERR(cqe) \
-			(!((cqe)->fast_path_cqe.status_flags & \
-			   ETH_FAST_PATH_RX_CQE_L4_XSUM_NO_VALIDATION_FLG) && \
-			 ((cqe)->fast_path_cqe.type_error_flags & \
-			  ETH_FAST_PATH_RX_CQE_L4_BAD_XSUM_FLG))
-
-#define BNX2X_RX_CSUM_OK(cqe) \
-			(!(BNX2X_L4_CSUM_ERR(cqe) || BNX2X_IP_CSUM_ERR(cqe)))
-
 #define BNX2X_PRS_FLAG_OVERETH_IPV4(flags) \
 				(((le16_to_cpu(flags) & \
 				   PARSING_FLAGS_OVER_ETHERNET_PROTOCOL) >> \
diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
index ad0743b..cbc56f2 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
@@ -617,6 +617,25 @@ static int bnx2x_alloc_rx_data(struct bnx2x *bp,
 	return 0;
 }
 
+static void bnx2x_csum_validate(struct sk_buff *skb, union eth_rx_cqe *cqe,
+				struct bnx2x_fastpath *fp)
+{
+	/* Do nothing if no IP/L4 csum validation was done */
+
+	if (cqe->fast_path_cqe.status_flags &
+	    (ETH_FAST_PATH_RX_CQE_IP_XSUM_NO_VALIDATION_FLG |
+	     ETH_FAST_PATH_RX_CQE_L4_XSUM_NO_VALIDATION_FLG))
+		return;
+
+	/* If both IP/L4 validation were done, check if an error was found. */
+
+	if (cqe->fast_path_cqe.type_error_flags &
+	    (ETH_FAST_PATH_RX_CQE_IP_BAD_XSUM_FLG |
+	     ETH_FAST_PATH_RX_CQE_L4_BAD_XSUM_FLG))
+		fp->eth_q_stats.hw_csum_err++;
+	else
+		skb->ip_summed = CHECKSUM_UNNECESSARY;
+}
 
 int bnx2x_rx_int(struct bnx2x_fastpath *fp, int budget)
 {
@@ -806,13 +825,9 @@ reuse_rx:
 
 		skb_checksum_none_assert(skb);
 
-		if (bp->dev->features & NETIF_F_RXCSUM) {
+		if (bp->dev->features & NETIF_F_RXCSUM)
+			bnx2x_csum_validate(skb, cqe, fp);
 
-			if (likely(BNX2X_RX_CSUM_OK(cqe)))
-				skb->ip_summed = CHECKSUM_UNNECESSARY;
-			else
-				fp->eth_q_stats.hw_csum_err++;
-		}
 
 		skb_record_rx_queue(skb, fp->rx_queue);