path: root/kernel
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authorEric Dumazet <>2015-03-05 13:47:48 -0800
committerDavid S. Miller <>2015-03-06 21:50:55 -0500
commit58025e46ea2d39f1840d5b1be5edea3297cfd23f (patch)
treecf0593edf6cac7b70da9213139ae481a013381c2 /kernel
parentfeb27d155dfabcb8baabe10367f25fc2b1bcede1 (diff)
net: gro: remove obsolete code from skb_gro_receive()
Some drivers use copybreak to copy tiny frames into smaller skb, and this smaller skb might not have skb->head_frag set for various reasons. skb_gro_receive() currently doesn't allow to aggregate the smaller skb into the previous GRO packet if this GRO packet has at least 2 MSS in it. Following workload easily demonstrates the problem. netperf -t TCP_RR -H target -- -r 3000,3000 (tcpdump shows one GRO packet with 2 MSS, plus one additional packet of 104 bytes that should have been appended.) It turns out that we can remove code from skb_gro_receive(), because commit 8a29111c7ca6 ("net: gro: allow to build full sized skb") and its followups removed the assumption that a GRO packet with a frag_list had to have an empty head. Removing this code allows the aggregation of the last (incomplete) frame in some RPC workloads. Note that tcp_gro_receive() already takes care of forcing a flush if necessary, including this case. If we want to avoid using frag_list in the first place (in forwarding workloads for example, as the outgoing NIC is generally not able to cope with skbs having a frag_list), we need to address this separately. Signed-off-by: Eric Dumazet <> Cc: Herbert Xu <> Signed-off-by: David S. Miller <>
Diffstat (limited to 'kernel')
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