From: Sean Tranchetti <stranche@codeaurora.org>
To: davem@davemloft.net, netdev@vger.kernel.org
Cc: Sean Tranchetti <stranche@codeaurora.org>,
Paolo Abeni <pabeni@redhat.com>,
Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Subject: [PATCH net-next] udp: Avoid post-GRO UDP checksum recalculation
Date: Thu, 23 May 2019 13:36:17 -0600 [thread overview]
Message-ID: <1558640177-10984-1-git-send-email-stranche@codeaurora.org> (raw)
Currently, when resegmenting an unexpected UDP GRO packet, the full UDP
checksum will be calculated for every new SKB created by skb_segment()
because the netdev features passed in by udp_rcv_segment() lack any
information about checksum offload capabilities.
We have no need to perform this calculation again, as
1) The GRO implementation guarantees that any packets making it to the
udp_rcv_segment() function had correct checksums, and, more
importantly,
2) Upon the successful return of udp_rcv_segment(), we immediately pull
the UDP header off and either queue the segment to the socket or
hand it off to a new protocol handler. In either case, the checksum
is not needed.
Fixes: cf329aa42b66 ("udp: cope with UDP GRO packet misdirection")
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Signed-off-by: Sean Tranchetti <stranche@codeaurora.org>
---
include/net/udp.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/include/net/udp.h b/include/net/udp.h
index d8ce937..6164d5c 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -472,11 +472,15 @@ static inline struct sk_buff *udp_rcv_segment(struct sock *sk,
struct sk_buff *skb, bool ipv4)
{
struct sk_buff *segs;
+ netdev_features_t features = NETIF_F_SG;
+
+ /* Avoid csum recalculation in skb_segment() */
+ features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
/* the GSO CB lays after the UDP one, no need to save and restore any
* CB fragment
*/
- segs = __skb_gso_segment(skb, NETIF_F_SG, false);
+ segs = __skb_gso_segment(skb, features, false);
if (unlikely(IS_ERR_OR_NULL(segs))) {
int segs_nr = skb_shinfo(skb)->gso_segs;
--
1.9.1
next reply other threads:[~2019-05-23 19:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-23 19:36 Sean Tranchetti [this message]
2019-05-24 12:50 ` [PATCH net-next] udp: Avoid post-GRO UDP checksum recalculation Paolo Abeni
2019-05-25 17:53 ` David Miller
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