Re: [PATCH net] net: thunderx: Fix TCP/UDP checksum offload for IPv6 pkts

On Wed, Nov 22, 2017 at 9:27 PM, Eric Dumazet [off-list ref] wrote:

On Wed, 2017-11-22 at 15:37 +0300, Aleksey Makarov wrote:

quoted

From: Sunil Goutham <redacted>

This fixes a previous patch which missed some changes
and due to which L3 checksum offload was getting enabled
for IPv6 pkts. And HW is dropping these pkts as it assumes
the pkt is IPv4 when IP csum offload is set in the SQ
descriptor.

Fixes: bbbb494fd005 ("net: thunderx: Enable TSO and checksum offloads
for ipv6")
Signed-off-by: Sunil Goutham <redacted>
Signed-off-by: Aleksey Makarov <redacted>
---
 drivers/net/ethernet/cavium/thunder/nicvf_queues.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c

b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
index d4496e9afcdf..184d5bdbe7e0 100644

--- a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
+++ b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c

@@ -1355,10 +1355,11 @@ nicvf_sq_add_hdr_subdesc(struct nicvf *nic,

struct snd_queue *sq, int qentry,

      /* Offload checksum calculation to HW */
      if (skb->ip_summed == CHECKSUM_PARTIAL) {
-             hdr->csum_l3 = 1; /* Enable IP csum calculation */
              hdr->l3_offset = skb_network_offset(skb);
              hdr->l4_offset = skb_transport_offset(skb);

+             /* Enable IP HDR csum calculation for V4 pkts */
+             hdr->csum_l3 = (ip.v4->version == 4) ? 1 : 0;

Have you tried to set hdr->csum_l3 to 0 regardless of version being 4
or 6 ?

This would remove the need for yet another conditional.

AFAIK, linux does not offload IPv4 header checksums to NIC, it is not
worth the trouble.

Looks like I misunderstood the IPSUM netdev feature flag.
Thanks, will check.

Sunil.

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