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From: Maciej Bielski <mba@semihalf.com>
To: dev@dpdk.org
Cc: Maciej Bielski <mba@semihalf.com>,
	Michal Krawczyk <mk@semihalf.com>,
	Marcin Wojtas <mw@semihalf.com>, Guy Tzalik <gtzalik@amazon.com>,
	Evgeny Schemeilin <evgenys@amazon.com>,
	Eduard Serra <eduser25@gmail.com>,
	igorc.mail@gmail.com, stable@dpdk.org
Subject: [dpdk-dev] [PATCH] net/ena: fix L4 cksum flags condition for TX
Date: Thu,  1 Aug 2019 13:45:36 +0200	[thread overview]
Message-ID: <20190801114536.318-1-mba@semihalf.com> (raw)

During an if-condition evaluation, a 2-bit flag evaluates to 'true' for
'0x1', '0x2' and '0x3'. Thus, from this perspective these flags are
indistinguishable. To make them distinct, respective bits must be
extracted with a mask and then checked for strict equality.

Specifically here, even if `PKT_TX_UDP_CKSUM` (value '0x3') was set, the
expression `mbuf->ol_flags & PKT_TX_TCP` (the second flag of value
'0x1') is evaluated first and the result is 'true'. In consequence, for
UDP packets the execution flow enters an incorrect branch.

Fixes: 56b8b9b7e5d2 (net/ena: convert to new Tx offloads API)
Cc: stable@dpdk.org

Signed-off-by: Maciej Bielski <mba@semihalf.com>
Reported-by: Eduard Serra <eduser25@gmail.com>
---
 drivers/net/ena/ena_ethdev.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ena/ena_ethdev.c b/drivers/net/ena/ena_ethdev.c
index f58334080..eb9d643f0 100644
--- a/drivers/net/ena/ena_ethdev.c
+++ b/drivers/net/ena/ena_ethdev.c
@@ -330,12 +330,13 @@ static inline void ena_tx_mbuf_prepare(struct rte_mbuf *mbuf,
 		}
 
 		/* check if L4 checksum is needed */
-		if ((mbuf->ol_flags & PKT_TX_TCP_CKSUM) &&
+		if (((mbuf->ol_flags & PKT_TX_L4_MASK) == PKT_TX_TCP_CKSUM) &&
 		    (queue_offloads & DEV_TX_OFFLOAD_TCP_CKSUM)) {
 			ena_tx_ctx->l4_proto = ENA_ETH_IO_L4_PROTO_TCP;
 			ena_tx_ctx->l4_csum_enable = true;
-		} else if ((mbuf->ol_flags & PKT_TX_UDP_CKSUM) &&
-			   (queue_offloads & DEV_TX_OFFLOAD_UDP_CKSUM)) {
+		} else if (((mbuf->ol_flags & PKT_TX_L4_MASK) ==
+				PKT_TX_UDP_CKSUM) &&
+				(queue_offloads & DEV_TX_OFFLOAD_UDP_CKSUM)) {
 			ena_tx_ctx->l4_proto = ENA_ETH_IO_L4_PROTO_UDP;
 			ena_tx_ctx->l4_csum_enable = true;
 		} else {
-- 
2.20.1


             reply	other threads:[~2019-08-01 11:45 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-01 11:45 Maciej Bielski [this message]
2019-08-01 12:08 ` Michał Krawczyk
2019-08-05 17:44   ` [dpdk-dev] [dpdk-stable] " Thomas Monjalon

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