diff options
| author | Yadu Kishore <kyk.segfault@gmail.com> | 2020-03-17 14:08:38 +0530 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-03-23 12:59:53 -0700 |
| commit | 1454c9fa91065847d77f619330c3f4cfb5328cd3 (patch) | |
| tree | 858891165da4f58adf1b95e57c91eb106abee6c2 /net/core | |
| parent | fe1f4fc10619ad874ed32554f842a121eed06076 (diff) | |
net: Make skb_segment not to compute checksum if network controller supports checksumming
Problem:
TCP checksum in the output path is not being offloaded during GSO
in the following case:
The network driver does not support scatter-gather but supports
checksum offload with NETIF_F_HW_CSUM.
Cause:
skb_segment calls skb_copy_and_csum_bits if the network driver
does not announce NETIF_F_SG. It does not check if the driver
supports NETIF_F_HW_CSUM.
So for devices which might want to offload checksum but do not support SG
there is currently no way to do so if GSO is enabled.
Solution:
In skb_segment check if the network controller does checksum and if so
call skb_copy_bits instead of skb_copy_and_csum_bits.
Testing:
Without the patch, ran iperf TCP traffic with NETIF_F_HW_CSUM enabled
in the network driver. Observed the TCP checksum offload is not happening
since the skbs received by the driver in the output path have
skb->ip_summed set to CHECKSUM_NONE.
With the patch ran iperf TCP traffic and observed that TCP checksum
is being offloaded with skb->ip_summed set to CHECKSUM_PARTIAL.
Also tested with the patch by disabling NETIF_F_HW_CSUM in the driver
to cover the newly introduced if-else code path in skb_segment.
Link: https://lore.kernel.org/netdev/CA+FuTSeYGYr3Umij+Mezk9CUcaxYwqEe5sPSuXF8jPE2yMFJAw@mail.gmail.com
Signed-off-by: Yadu Kishore <kyk.segfault@gmail.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/skbuff.c | 23 |
1 files changed, 15 insertions, 8 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index e1101a4f90a6..621b4479fee1 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3926,14 +3926,21 @@ normal: goto perform_csum_check; if (!sg) { - if (!nskb->remcsum_offload) - nskb->ip_summed = CHECKSUM_NONE; - SKB_GSO_CB(nskb)->csum = - skb_copy_and_csum_bits(head_skb, offset, - skb_put(nskb, len), - len, 0); - SKB_GSO_CB(nskb)->csum_start = - skb_headroom(nskb) + doffset; + if (!csum) { + if (!nskb->remcsum_offload) + nskb->ip_summed = CHECKSUM_NONE; + SKB_GSO_CB(nskb)->csum = + skb_copy_and_csum_bits(head_skb, offset, + skb_put(nskb, + len), + len, 0); + SKB_GSO_CB(nskb)->csum_start = + skb_headroom(nskb) + doffset; + } else { + skb_copy_bits(head_skb, offset, + skb_put(nskb, len), + len); + } continue; } |