kernel/git/stable/linux.git/include/net/tcp.h, branch linux-3.5.y

tcp: bool conversions

2012-05-17T18:59:59+00:00

bool conversions where possible. __inline__ -> inline space cleanups Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

tcp: Move rcvq sending to tcp_input.c

2012-05-11T03:24:35+00:00

It actually works on the input queue and will use its read mem routines, thus it's better to have in in the tcp_input.c file. Signed-off-by: Pavel Emelyanov Acked-by: Eric Dumazet Signed-off-by: David S. Miller

tcp: be more strict before accepting ECN negociation

2012-05-04T16:05:27+00:00

It appears some networks play bad games with the two bits reserved for ECN. This can trigger false congestion notifications and very slow transferts. Since RFC 3168 (6.1.1) forbids SYN packets to carry CT bits, we can disable TCP ECN negociation if it happens we receive mangled CT bits in the SYN packet. Signed-off-by: Eric Dumazet Cc: Perry Lorier Cc: Matt Mathis Cc: Yuchung Cheng Cc: Neal Cardwell Cc: Wilmer van der Gaast Cc: Ankur Jain Cc: Tom Herbert Cc: Dave Täht Acked-by: Neal Cardwell Signed-off-by: David S. Miller

net: implement tcp coalescing in tcp_queue_rcv()

2012-05-03T01:11:11+00:00

Extend tcp coalescing implementing it from tcp_queue_rcv(), the main receiver function when application is not blocked in recvmsg(). Function tcp_queue_rcv() is moved a bit to allow its call from tcp_data_queue() This gives good results especially if GRO could not kick, and if skb head is a fragment. Signed-off-by: Eric Dumazet Cc: Alexander Duyck Cc: Neal Cardwell Cc: Tom Herbert Signed-off-by: David S. Miller

tcp: early retransmit: delayed fast retransmit

2012-05-03T00:56:10+00:00

Implementing the advanced early retransmit (sysctl_tcp_early_retrans==2). Delays the fast retransmit by an interval of RTT/4. We borrow the RTO timer to implement the delay. If we receive another ACK or send a new packet, the timer is cancelled and restored to original RTO value offset by time elapsed. When the delayed-ER timer fires, we enter fast recovery and perform fast retransmit. Signed-off-by: Yuchung Cheng Acked-by: Neal Cardwell Signed-off-by: David S. Miller

tcp: early retransmit

2012-05-03T00:56:10+00:00

This patch implements RFC 5827 early retransmit (ER) for TCP. It reduces DUPACK threshold (dupthresh) if outstanding packets are less than 4 to recover losses by fast recovery instead of timeout. While the algorithm is simple, small but frequent network reordering makes this feature dangerous: the connection repeatedly enter false recovery and degrade performance. Therefore we implement a mitigation suggested in the appendix of the RFC that delays entering fast recovery by a small interval, i.e., RTT/4. Currently ER is conservative and is disabled for the rest of the connection after the first reordering event. A large scale web server experiment on the performance impact of ER is summarized in section 6 of the paper "Proportional Rate Reduction for TCP”, IMC 2011. http://conferences.sigcomm.org/imc/2011/docs/p155.pdf Note that Linux has a similar feature called THIN_DUPACK. The differences are THIN_DUPACK do not mitigate reorderings and is only used after slow start. Currently ER is disabled if THIN_DUPACK is enabled. I would be happy to merge THIN_DUPACK feature with ER if people think it's a good idea. ER is enabled by sysctl_tcp_early_retrans: 0: Disables ER 1: Reduce dupthresh to packets_out - 1 when outstanding packets < 4. 2: (Default) reduce dupthresh like mode 1. In addition, delay entering fast recovery by RTT/4. Note: mode 2 is implemented in the third part of this patch series. Signed-off-by: Yuchung Cheng Acked-by: Neal Cardwell Signed-off-by: David S. Miller

ipv6: RTAX_FEATURE_ALLFRAG causes inefficient TCP segment sizing

2012-04-27T04:03:34+00:00

Quoting Tore Anderson from : https://bugzilla.kernel.org/show_bug.cgi?id=42572 When RTAX_FEATURE_ALLFRAG is set on a route, the effective TCP segment size does not take into account the size of the IPv6 Fragmentation header that needs to be included in outbound packets, causing every transmitted TCP segment to be fragmented across two IPv6 packets, the latter of which will only contain 8 bytes of actual payload. RTAX_FEATURE_ALLFRAG is typically set on a route in response to receving a ICMPv6 Packet Too Big message indicating a Path MTU of less than 1280 bytes. 1280 bytes is the minimum IPv6 MTU, however ICMPv6 PTBs with MTU < 1280 are still valid, in particular when an IPv6 packet is sent to an IPv4 destination through a stateless translator. Any ICMPv4 Need To Fragment packets originated from the IPv4 part of the path will be translated to ICMPv6 PTB which may then indicate an MTU of less than 1280. The Linux kernel refuses to reduce the effective MTU to anything below 1280 bytes, instead it sets it to exactly 1280 bytes, and RTAX_FEATURE_ALLFRAG is also set. However, the TCP segment size appears to be set to 1240 bytes (1280 Path MTU - 40 bytes of IPv6 header), instead of 1232 (additionally taking into account the 8 bytes required by the IPv6 Fragmentation extension header). This in turn results in rather inefficient transmission, as every transmitted TCP segment now is split in two fragments containing 1232+8 bytes of payload. After this patch, all the outgoing packets that includes a Fragmentation header all are "atomic" or "non-fragmented" fragments, i.e., they both have Offset=0 and More Fragments=0. With help from David S. Miller Reported-by: Tore Anderson Signed-off-by: Eric Dumazet Cc: Maciej Żenczykowski Cc: Tom Herbert Tested-by: Tore Anderson Signed-off-by: David S. Miller

tcp: move duplicate code from tcp_v4_init_sock()/tcp_v6_init_sock()

2012-04-21T20:36:42+00:00

This commit moves the (substantial) common code shared between tcp_v4_init_sock() and tcp_v6_init_sock() to a new address-family independent function, tcp_init_sock(). Centralizing this functionality should help avoid drift issues, e.g. where the IPv4 side is updated without a corresponding update to IPv6. There was already some drift: IPv4 initialized snd_cwnd to TCP_INIT_CWND, while the IPv6 side was still initializing snd_cwnd to 2 (in this case it should not matter, since snd_cwnd is also initialized in tcp_init_metrics(), but the general risks and maintenance overhead remain). When diffing the old and new code, note that new tcp_init_sock() function uses the order of steps from the tcp_v4_init_sock() implementation (the order is slightly different in tcp_v6_init_sock()). Signed-off-by: Neal Cardwell Acked-by: Eric Dumazet Signed-off-by: David S. Miller

tcp: Initial repair mode

2012-04-21T19:52:25+00:00

This includes (according the the previous description): * TCP_REPAIR sockoption This one just puts the socket in/out of the repair mode. Allowed for CAP_NET_ADMIN and for closed/establised sockets only. When repair mode is turned off and the socket happens to be in the established state the window probe is sent to the peer to 'unlock' the connection. * TCP_REPAIR_QUEUE sockoption This one sets the queue which we're about to repair. The 'no-queue' is set by default. * TCP_QUEUE_SEQ socoption Sets the write_seq/rcv_nxt of a selected repaired queue. Allowed for TCP_CLOSE-d sockets only. When the socket changes its state the other seq-s are changed by the kernel according to the protocol rules (most of the existing code is actually reused). * Ability to forcibly bind a socket to a port The sk->sk_reuse is set to SK_FORCE_REUSE. * Immediate connect modification The connect syscall initializes the connection, then directly jumps to the code which finalizes it. * Silent close modification The close just aborts the connection (similar to SO_LINGER with 0 time) but without sending any FIN/RST-s to peer. Signed-off-by: Pavel Emelyanov Signed-off-by: David S. Miller

tcp: Move code around

2012-04-21T19:52:25+00:00

This is just the preparation patch, which makes the needed for TCP repair code ready for use. Signed-off-by: Pavel Emelyanov Signed-off-by: David S. Miller