linux-toradex.git/net/ipv4/tcp_timer.c, branch v4.4.2

tcp: fix Fast Open snmp over-counting bug

2015-11-20T15:51:12+00:00

Fix incrementing TCPFastOpenActiveFailed snmp stats multiple times
when the handshake experiences multiple SYN timeouts.

Signed-off-by: Yuchung Cheng 
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

tcp: disable Fast Open on timeouts after handshake

2015-11-20T15:51:12+00:00

Some middle-boxes black-hole the data after the Fast Open handshake
(https://www.ietf.org/proceedings/94/slides/slides-94-tcpm-13.pdf).
The exact reason is unknown. The work-around is to disable Fast Open
temporarily after multiple recurring timeouts with few or no data
delivered in the established state.

Signed-off-by: Yuchung Cheng 
Signed-off-by: Eric Dumazet 
Reported-by: Christoph Paasch 
Signed-off-by: David S. Miller

tcp: change type of alive from int to bool

2015-10-12T12:15:03+00:00

The alive parameter of tcp_orphan_retries, indicates
whether the connection is assumed alive or not.
In the function and all places calling it is used as a boolean value.

Therefore this changes the type of alive to bool in the function
definition and all calling locations.

Since tcp_orphan_tries is a tcp_timer.c local function no change in
any other file or header is necessary.

Signed-off-by: Richard Sailer 
Signed-off-by: David S. Miller

tcp: do not export tcp_init_xmit_timers()

2015-07-10T04:44:38+00:00

After commit 900f65d361d3 ("tcp: move duplicate code from
tcp_v4_init_sock()/tcp_v6_init_sock()"), we no longer
need to export tcp_init_xmit_timers()

Signed-off-by: Eric Dumazet 
Cc: Neal Cardwell 
Acked-by: Neal Cardwell 
Signed-off-by: David S. Miller

tcp: introduce tcp_under_memory_pressure()

2015-05-18T02:45:48+00:00

Introduce an optimized version of sk_under_memory_pressure()
for TCP. Our intent is to use it in fast paths.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

tcp: add TCPWinProbe and TCPKeepAlive SNMP counters

2015-05-09T20:42:32+00:00

Diagnosing problems related to Window Probes has been hard because
we lack a counter.

TCPWinProbe counts the number of ACK packets a sender has to send
at regular intervals to make sure a reverse ACK packet opening back
a window had not been lost.

TCPKeepAlive counts the number of ACK packets sent to keep TCP
flows alive (SO_KEEPALIVE)

Signed-off-by: Eric Dumazet 
Signed-off-by: Yuchung Cheng 
Acked-by: Neal Cardwell 
Acked-by: Nandita Dukkipati 
Signed-off-by: David S. Miller

tcp: RFC7413 option support for Fast Open client

2015-04-07T22:36:39+00:00

Fast Open has been using an experimental option with a magic number
(RFC6994). This patch makes the client by default use the RFC7413
option (34) to get and send Fast Open cookies.  This patch makes
the client solicit cookies from a given server first with the
RFC7413 option. If that fails to elicit a cookie, then it tries
the RFC6994 experimental option. If that also fails, it uses the
RFC7413 option on all subsequent connect attempts.  If the server
returns a Fast Open cookie then the client caches the form of the
option that successfully elicited a cookie, and uses that form on
later connects when it presents that cookie.

The idea is to gradually obsolete the use of experimental options as
the servers and clients upgrade, while keeping the interoperability
meanwhile.

Signed-off-by: Daniel Lee 
Signed-off-by: Yuchung Cheng 
Signed-off-by: Neal Cardwell 
Signed-off-by: David S. Miller

inet: remove sk_listener parameter from syn_ack_timeout()

2015-03-23T20:52:25+00:00

It is not needed, and req->sk_listener points to the listener anyway.
request_sock argument can be const.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

inet: get rid of central tcp/dccp listener timer

2015-03-20T16:40:25+00:00

One of the major issue for TCP is the SYNACK rtx handling,
done by inet_csk_reqsk_queue_prune(), fired by the keepalive
timer of a TCP_LISTEN socket.

This function runs for awful long times, with socket lock held,
meaning that other cpus needing this lock have to spin for hundred of ms.

SYNACK are sent in huge bursts, likely to cause severe drops anyway.

This model was OK 15 years ago when memory was very tight.

We now can afford to have a timer per request sock.

Timer invocations no longer need to lock the listener,
and can be run from all cpus in parallel.

With following patch increasing somaxconn width to 32 bits,
I tested a listener with more than 4 million active request sockets,
and a steady SYNFLOOD of ~200,000 SYN per second.
Host was sending ~830,000 SYNACK per second.

This is ~100 times more what we could achieve before this patch.

Later, we will get rid of the listener hash and use ehash instead.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

ipv4: Create probe timer for tcp PMTU as per RFC4821

2015-03-06T19:57:42+00:00

As per RFC4821 7.3.  Selecting Probe Size, a probe timer should
be armed once probing has converged. Once this timer expired,
probing again to take advantage of any path PMTU change. The
recommended probing interval is 10 minutes per RFC1981. Probing
interval could be sysctled by sysctl_tcp_probe_interval.

Eric Dumazet suggested to implement pseudo timer based on 32bits
jiffies tcp_time_stamp instead of using classic timer for such
rare event.

Signed-off-by: Fan Du 
Signed-off-by: David S. Miller