On 7/30/21 2:11 PM, Olivier Matz wrote:

On Wed, Jul 28, 2021 at 06:46:53PM +0300, Andrew Rybchenko wrote:

quoted

On 7/7/21 12:40 PM, Mohsin Kazmi wrote:

quoted

Preparation the headers for the hardware offload
misses the outer ipv4 checksum offload.
It results in bad checksum computed by hardware NIC.

This patch fixes the issue by setting the outer ipv4
checksum field to 0.

Fixes: 4fb7e803eb1a ("ethdev: add Tx preparation")
Cc: stable@dpdk.org

Signed-off-by: Mohsin Kazmi <redacted>
Acked-by: Qi Zhang <redacted>
---
v3:
     * Update the conditional test with PKT_TX_OUTER_IP_CKSUM.
     * Update the commit title with "Intel-specific".

v2:
     * Update the commit message with Fixes.

   lib/net/rte_net.h | 15 +++++++++++++--
   1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/lib/net/rte_net.h b/lib/net/rte_net.h
index 434435ffa2..3f4c8c58b9 100644
--- a/lib/net/rte_net.h
+++ b/lib/net/rte_net.h

@@ -125,11 +125,22 @@ rte_net_intel_cksum_flags_prepare(struct rte_mbuf *m, uint64_t ol_flags)
   	 * Mainly it is required to avoid fragmented headers check if
   	 * no offloads are requested.
   	 */
-	if (!(ol_flags & (PKT_TX_IP_CKSUM | PKT_TX_L4_MASK | PKT_TX_TCP_SEG)))
+	if (!(ol_flags & (PKT_TX_IP_CKSUM | PKT_TX_L4_MASK | PKT_TX_TCP_SEG |
+			  PKT_TX_OUTER_IP_CKSUM)))
   		return 0;
-	if (ol_flags & (PKT_TX_OUTER_IPV4 | PKT_TX_OUTER_IPV6))
+	if (ol_flags & (PKT_TX_OUTER_IPV4 | PKT_TX_OUTER_IPV6)) {
   		inner_l3_offset += m->outer_l2_len + m->outer_l3_len;
+		/*
+		 * prepare outer ipv4 header checksum by setting it to 0,
+		 * in order to be computed by hardware NICs.
+		 */
+		if (ol_flags & PKT_TX_OUTER_IP_CKSUM) {
+			ipv4_hdr = rte_pktmbuf_mtod_offset(m,
+					struct rte_ipv4_hdr *, m->outer_l2_len);
+			ipv4_hdr->hdr_checksum = 0;

Here we assume that the field is located in the first segment.
Unlikely but it still could be false. We must handle it properly.

This is specified in the API comment, so I think it has to be checked
by the caller.

If no, what's the point to spoil memory here if stricter check is
done few lines below.

quoted

quoted

+		}
+	}
   	/*
   	 * Check if headers are fragmented.