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Date: Tue, 05 May 2015 02:16:39 +0100
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC: akpm@...ux-foundation.org, "David S. Miller" <davem@...emloft.net>,
"Eric Dumazet" <edumazet@...gle.com>,
"Yuchung Cheng" <ycheng@...gle.com>,
"Denys Fedoryshchenko" <nuclearcat@...learcat.com>
Subject: [PATCH 3.2 206/221] tcp: make connect() mem charging friendly
3.2.69-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@...gle.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@...learcat.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Acked-by: Yuchung Cheng <ycheng@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
[bwh: Backported to 3.2:
- Drop the Fast Open changes
- Adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.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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