[dpdk-stable] patch 'net/tap: fix Rx checksum flags on TCP packets' has been queued to stable release 20.11.3

[luca.boccassi at gmail.com]

Hi,

FYI, your patch has been queued to stable release 20.11.3

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 07/14/21. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/bluca/dpdk-stable

This queued commit can be viewed at:
https://github.com/bluca/dpdk-stable/commit/f4a79bb95234970d33823921e19d6f25de3df95b

Thanks.

Luca Boccassi

---
>From f4a79bb95234970d33823921e19d6f25de3df95b Mon Sep 17 00:00:00 2001
From: Olivier Matz <olivier.matz at 6wind.com>
Date: Wed, 30 Jun 2021 15:51:56 +0200
Subject: [PATCH] net/tap: fix Rx checksum flags on TCP packets

[ upstream commit 375474b4d9a89456bd0d8baa4b610d3157ee262c ]

Since commit d5df2ae0428a ("net: fix unneeded replacement of TCP
checksum 0"), the functions rte_ipv4_udptcp_cksum() or
rte_ipv6_udptcp_cksum() can return either 0x0000 or 0xffff when used to
verify a packet containing a valid checksum.

This new behavior broke the checksum verification in tap driver for TCP
packets: these packets are marked with PKT_RX_L4_CKSUM_BAD.

Fix this by checking the 2 possible values. A next commit will introduce
a checksum verification helper to simplify this a bit.

Fixes: d5df2ae0428a ("net: fix unneeded replacement of TCP checksum 0")

Signed-off-by: Olivier Matz <olivier.matz at 6wind.com>
Acked-by: Andrew Rybchenko <andrew.rybchenko at oktetlabs.ru>
---
 drivers/net/tap/rte_eth_tap.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
index cf42809461..691566b263 100644
--- a/drivers/net/tap/rte_eth_tap.c
+++ b/drivers/net/tap/rte_eth_tap.c
@@ -350,6 +350,8 @@ tap_verify_csum(struct rte_mbuf *mbuf)
 		return;
 	}
 	if (l4 == RTE_PTYPE_L4_UDP || l4 == RTE_PTYPE_L4_TCP) {
+		int cksum_ok;
+
 		l4_hdr = rte_pktmbuf_mtod_offset(mbuf, void *, l2_len + l3_len);
 		/* Don't verify checksum for multi-segment packets. */
 		if (mbuf->nb_segs > 1)
@@ -367,13 +369,13 @@ tap_verify_csum(struct rte_mbuf *mbuf)
 					return;
 				}
 			}
-			cksum = ~rte_ipv4_udptcp_cksum(l3_hdr, l4_hdr);
+			cksum = rte_ipv4_udptcp_cksum(l3_hdr, l4_hdr);
 		} else { /* l3 == RTE_PTYPE_L3_IPV6, checked above */
-			cksum = ~rte_ipv6_udptcp_cksum(l3_hdr, l4_hdr);
+			cksum = rte_ipv6_udptcp_cksum(l3_hdr, l4_hdr);
 		}
-		mbuf->ol_flags |= cksum ?
-			PKT_RX_L4_CKSUM_BAD :
-			PKT_RX_L4_CKSUM_GOOD;
+		cksum_ok = (cksum == 0) || (cksum == 0xffff);
+		mbuf->ol_flags |= cksum_ok ?
+			PKT_RX_L4_CKSUM_GOOD : PKT_RX_L4_CKSUM_BAD;
 	}
 }
 
-- 
2.30.2

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2021-07-12 13:41:40.200299951 +0100
+++ 0068-net-tap-fix-Rx-checksum-flags-on-TCP-packets.patch	2021-07-12 13:41:36.566124194 +0100
@@ -1 +1 @@
-From 375474b4d9a89456bd0d8baa4b610d3157ee262c Mon Sep 17 00:00:00 2001
+From f4a79bb95234970d33823921e19d6f25de3df95b Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit 375474b4d9a89456bd0d8baa4b610d3157ee262c ]
+
@@ -18 +19,0 @@
-Cc: stable at dpdk.org
@@ -27 +28 @@
-index 5513cfd2d7..5429f611c1 100644
+index cf42809461..691566b263 100644