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net: avoid skb_warn_bad_offload false positives on UFO

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skb_warn_bad_offload triggers a warning when an skb enters the GSO
stack at __skb_gso_segment that does not have CHECKSUM_PARTIAL
checksum offload set.

Commit b2504a5dbe ("net: reduce skb_warn_bad_offload() noise")
observed that SKB_GSO_DODGY producers can trigger the check and
that passing those packets through the GSO handlers will fix it
up. But, the software UFO handler will set ip_summed to
CHECKSUM_NONE.

When __skb_gso_segment is called from the receive path, this
triggers the warning again.

Make UFO set CHECKSUM_UNNECESSARY instead of CHECKSUM_NONE. On
Tx these two are equivalent. On Rx, this better matches the
skb state (checksum computed), as CHECKSUM_NONE here means no
checksum computed.

See also this thread for context:
http://patchwork.ozlabs.org/patch/799015/

Fixes: b2504a5dbe ("net: reduce skb_warn_bad_offload() noise")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Willem de Bruijn 2017-08-08 14:22:55 -04:00 committed by David S. Miller
parent bbae08e592
commit 8d63bee643
3 changed files with 3 additions and 3 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

2
net/core/dev.c
View file

@ -2739,7 +2739,7 @@ static inline bool skb_needs_check(struct sk_buff *skb, bool tx_path)
{ {
if (tx_path) if (tx_path)
return skb->ip_summed != CHECKSUM_PARTIAL && return skb->ip_summed != CHECKSUM_PARTIAL &&
skb->ip_summed != CHECKSUM_NONE; skb->ip_summed != CHECKSUM_UNNECESSARY;
return skb->ip_summed == CHECKSUM_NONE; return skb->ip_summed == CHECKSUM_NONE;
} }

2
net/ipv4/udp_offload.c
View file

@ -235,7 +235,7 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
if (uh->check == 0) if (uh->check == 0)
uh->check = CSUM_MANGLED_0; uh->check = CSUM_MANGLED_0;
skb->ip_summed = CHECKSUM_NONE; skb->ip_summed = CHECKSUM_UNNECESSARY;
/* If there is no outer header we can fake a checksum offload /* If there is no outer header we can fake a checksum offload
* due to the fact that we have already done the checksum in * due to the fact that we have already done the checksum in

2
net/ipv6/udp_offload.c
View file

@ -72,7 +72,7 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
if (uh->check == 0) if (uh->check == 0)
uh->check = CSUM_MANGLED_0; uh->check = CSUM_MANGLED_0;
skb->ip_summed = CHECKSUM_NONE; skb->ip_summed = CHECKSUM_UNNECESSARY;
/* If there is no outer header we can fake a checksum offload /* If there is no outer header we can fake a checksum offload
* due to the fact that we have already done the checksum in * due to the fact that we have already done the checksum in