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authorEric Dumazet <edumazet@google.com>2012-07-23 09:48:52 +0200
committerDavid S. Miller <davem@davemloft.net>2012-07-23 00:58:46 -0700
commit563d34d05786263893ba4a1042eb9b9374127cf5 (patch)
treee9ce502c1f32bea966c81d5597d0a29eb4b9d244 /include/linux
parentc3def943c7117d42caaed3478731ea7c3c87190e (diff)
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tcp: dont drop MTU reduction indications
ICMP messages generated in output path if frame length is bigger than mtu are actually lost because socket is owned by user (doing the xmit) One example is the ipgre_tunnel_xmit() calling icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); We had a similar case fixed in commit a34a101e1e6 (ipv6: disable GSO on sockets hitting dst_allfrag). Problem of such fix is that it relied on retransmit timers, so short tcp sessions paid a too big latency increase price. This patch uses the tcp_release_cb() infrastructure so that MTU reduction messages (ICMP messages) are not lost, and no extra delay is added in TCP transmits. Reported-by: Maciej Żenczykowski <maze@google.com> Diagnosed-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Nandita Dukkipati <nanditad@google.com> Cc: Tom Herbert <therbert@google.com> Cc: Tore Anderson <tore@fud.no> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/tcp.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 2761856987b2..eb125a4c30b3 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -493,6 +493,9 @@ struct tcp_sock {
u32 probe_seq_start;
u32 probe_seq_end;
} mtu_probe;
+ u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
+ * while socket was owned by user.
+ */
#ifdef CONFIG_TCP_MD5SIG
/* TCP AF-Specific parts; only used by MD5 Signature support so far */
@@ -518,6 +521,9 @@ enum tsq_flags {
TCP_TSQ_DEFERRED, /* tcp_tasklet_func() found socket was owned */
TCP_WRITE_TIMER_DEFERRED, /* tcp_write_timer() found socket was owned */
TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
+ TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call
+ * tcp_v{4|6}_mtu_reduced()
+ */
};
static inline struct tcp_sock *tcp_sk(const struct sock *sk)