net/tap: fix rx cksum flags on TCP packets

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")
Cc: stable@dpdk.org
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>

diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
index e7b185a..71282e8 100644 (file)
--- a/drivers/net/tap/rte_eth_tap.c
+++ b/drivers/net/tap/rte_eth_tap.c
@@ -346,6 +346,8 @@ 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)
@@ -363,13 +365,13 @@ 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;
        }
 }