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 8a29111c7c
("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>
This commit is contained in:
parent
feb27d155d
commit
58025e46ea
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@ -3206,10 +3206,9 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
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struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
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unsigned int offset = skb_gro_offset(skb);
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unsigned int headlen = skb_headlen(skb);
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struct sk_buff *nskb, *lp, *p = *head;
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unsigned int len = skb_gro_len(skb);
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struct sk_buff *lp, *p = *head;
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unsigned int delta_truesize;
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unsigned int headroom;
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if (unlikely(p->len + len >= 65536))
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return -E2BIG;
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@ -3276,48 +3275,6 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
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NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
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goto done;
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}
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/* switch back to head shinfo */
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pinfo = skb_shinfo(p);
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if (pinfo->frag_list)
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goto merge;
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if (skb_gro_len(p) != pinfo->gso_size)
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return -E2BIG;
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headroom = skb_headroom(p);
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nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC);
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if (unlikely(!nskb))
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return -ENOMEM;
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__copy_skb_header(nskb, p);
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nskb->mac_len = p->mac_len;
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skb_reserve(nskb, headroom);
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__skb_put(nskb, skb_gro_offset(p));
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skb_set_mac_header(nskb, skb_mac_header(p) - p->data);
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skb_set_network_header(nskb, skb_network_offset(p));
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skb_set_transport_header(nskb, skb_transport_offset(p));
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__skb_pull(p, skb_gro_offset(p));
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memcpy(skb_mac_header(nskb), skb_mac_header(p),
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p->data - skb_mac_header(p));
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skb_shinfo(nskb)->frag_list = p;
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skb_shinfo(nskb)->gso_size = pinfo->gso_size;
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pinfo->gso_size = 0;
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__skb_header_release(p);
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NAPI_GRO_CB(nskb)->last = p;
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nskb->data_len += p->len;
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nskb->truesize += p->truesize;
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nskb->len += p->len;
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*head = nskb;
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nskb->next = p->next;
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p->next = NULL;
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p = nskb;
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merge:
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delta_truesize = skb->truesize;
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