From: Yadu Kishore <kyk.segfault@gmail.com>
To: davem@davemloft.net
Cc: David.Laight@aculab.com, eric.dumazet@gmail.com,
kyk.segfault@gmail.com, netdev@vger.kernel.org,
willemdebruijn.kernel@gmail.com
Subject: [PATCH v3] net: Make skb_segment not to compute checksum if network controller supports checksumming
Date: Tue, 17 Mar 2020 14:08:38 +0530 [thread overview]
Message-ID: <1584434318-27980-1-git-send-email-kyk.segfault@gmail.com> (raw)
In-Reply-To: <20200313.110542.570427563998639331.davem@davemloft.net>
> I think you can rebase and submit against net-next.
> If your patch isn't active in the networking development patchwork instance,
> it is not pending to be applied and you must resend it.
Rebasing the patch on net-next and resending it.
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>
---
net/core/skbuff.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index e1101a4..621b447 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3926,14 +3926,21 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
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;
}
--
2.7.4
next prev parent reply other threads:[~2020-03-17 8:39 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-04 5:55 TCP checksum not offloaded during GSO Yadu Kishore
2020-02-05 21:43 ` Willem de Bruijn
2020-02-21 5:13 ` [PATCH] net: Make skb_segment not to compute checksum if network controller supports checksumming Yadu Kishore
2020-02-23 2:41 ` Willem de Bruijn
2020-02-28 5:24 ` Yadu Kishore
2020-02-28 14:30 ` Willem de Bruijn
2020-02-28 20:01 ` David Miller
2020-03-02 6:51 ` [PATCH v2] " Yadu Kishore
2020-03-02 8:42 ` Yadu Kishore
2020-03-02 15:19 ` David Laight
2020-03-03 9:15 ` Yadu Kishore
2020-03-03 9:56 ` David Laight
2020-03-05 6:32 ` Yadu Kishore
2020-03-05 16:06 ` Willem de Bruijn
2020-03-05 17:00 ` David Laight
2020-03-05 17:19 ` Eric Dumazet
2020-03-06 17:12 ` David Laight
2020-03-13 6:36 ` Yadu Kishore
2020-03-13 13:57 ` Willem de Bruijn
2020-03-13 14:04 ` David Laight
2020-03-13 18:05 ` David Miller
2020-03-17 8:38 ` Yadu Kishore [this message]
2020-03-22 3:06 ` [PATCH v3] " David Miller
2020-03-22 14:40 ` Willem de Bruijn
2020-03-23 20:00 ` David Miller
2020-03-22 19:53 ` [PATCH v2] " Tom Herbert
2020-03-23 9:15 ` David Laight
2020-02-06 12:13 ` TCP checksum not offloaded during GSO David Laight
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