-
Eric Dumazet authored
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 8a29111c ("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 <edumazet@google.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by:
David S. Miller <davem@davemloft.net>
58025e46