| From | Ben Hutchings <> | Date | Tue, 05 May 2015 02:16:39 +0100 | Subject | [PATCH 3.2 206/221] tcp: make connect() mem charging friendly |
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3.2.69-rc1 review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet <edumazet@google.com>
[ Upstream commit 355a901e6cf1b2b763ec85caa2a9f04fbcc4ab4a ]
While working on sk_forward_alloc problems reported by Denys Fedoryshchenko, we found that tcp connect() (and fastopen) do not call sk_wmem_schedule() for SYN packet (and/or SYN/DATA packet), so sk_forward_alloc is negative while connect is in progress.
We can fix this by calling regular sk_stream_alloc_skb() both for the SYN packet (in tcp_connect()) and the syn_data packet in tcp_send_syn_data()
Then, tcp_send_syn_data() can avoid copying syn_data as we simply can manipulate syn_data->cb[] to remove SYN flag (and increment seq)
Instead of open coding memcpy_fromiovecend(), simply use this helper.
This leaves in socket write queue clean fast clone skbs.
This was tested against our fastopen packetdrill tests.
Reported-by: Denys Fedoryshchenko <nuclearcat@nuclearcat.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.2: - Drop the Fast Open changes - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- net/ipv4/tcp_output.c | 62 ++++++++++++++++++++++----------------------------- 1 file changed, 27 insertions(+), 35 deletions(-)
--- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2628,13 +2628,10 @@ int tcp_connect(struct sock *sk) tcp_connect_init(sk); - buff = alloc_skb_fclone(MAX_TCP_HEADER + 15, sk->sk_allocation); - if (unlikely(buff == NULL)) + buff = sk_stream_alloc_skb(sk, 0, sk->sk_allocation); + if (unlikely(!buff)) return -ENOBUFS; - /* Reserve space for headers. */ - skb_reserve(buff, MAX_TCP_HEADER); - tp->snd_nxt = tp->write_seq; tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); TCP_ECN_send_syn(sk, buff);
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