linux-toradex.git/include/net/sctp/command.h, branch v4.9.16

sctp: handle association restarts when the socket is closed.

2014-10-06T04:21:45+00:00

Currently association restarts do not take into consideration the
state of the socket.  When a restart happens, the current assocation
simply transitions into established state.  This creates a condition
where a remote system, through a the restart procedure, may create a
local association that is no way reachable by user.  The conditions
to trigger this are as follows:
  1) Remote does not acknoledge some data causing data to remain
     outstanding.
  2) Local application calls close() on the socket.  Since data
     is still outstanding, the association is placed in SHUTDOWN_PENDING
     state.  However, the socket is closed.
  3) The remote tries to create a new association, triggering a restart
     on the local system.  The association moves from SHUTDOWN_PENDING
     to ESTABLISHED.  At this point, it is no longer reachable by
     any socket on the local system.

This patch addresses the above situation by moving the newly ESTABLISHED
association into SHUTDOWN-SENT state and bundling a SHUTDOWN after
the COOKIE-ACK chunk.  This way, the restarted associate immidiately
enters the shutdown procedure and forces the termination of the
unreachable association.

Reported-by: David Laight 
Signed-off-by: Vlad Yasevich 
Signed-off-by: David S. Miller

net: sctp: Use pointers (not array indexes) to access sctp_cmd_seq_t.cmds[].

2014-07-08T21:39:00+00:00

Using pointers into sctp_cmd_seq_t.cmds[] lets the compiler generate much
better code.
Use the last entry first to optimise the overflow check.

Signed-off-by: David Laight 
Signed-off-by: David S. Miller

net: sctp: Optimise the way 'sctp_arg_t' values are initialised.

2014-07-08T21:39:00+00:00

Even if memset() is inlined (as on x86) using it to zero the union
generates a memory word write of zero, followed by a write of the
smaller field, and then a read of the word.
As well as being a lot of instructions the sequence is unlikely to
be optimised by the store-load forward hardware so will be slow.

Instead allocate a field of the union that is the same size as the
entire union and write a zero value to it. The compiler will then
generate the required value in a register.

Zeroing the union shouldn't be necessary, but this patch series isn't
intended to have a behavioural change.

Signed-off-by: David Laight 
Signed-off-by: David S. Miller

net: sctp: Inline the functions from command.c

2014-07-08T21:38:48+00:00

sctp_init_cmd_seq() and sctp_next_cmd() are only called from one place.
The call sequence for sctp_add_cmd_sf() is likely to be longer than
the inlined code.
With sctp_add_cmd_sf() inlined the compiler can optimise repeated calls.

Signed-off-by: David Laight 
Signed-off-by: David S. Miller

include/net/: Fix FSF address in file headers

2013-12-06T17:37:56+00:00

Several files refer to an old address for the Free Software Foundation
in the file header comment.  Resolve by replacing the address with
the URL  so that we do not have to keep
updating the header comments anytime the address changes.

Signed-off-by: Jeff Kirsher 
Signed-off-by: David S. Miller

net: sctp: trivial: update bug report in header comment

2013-08-09T18:33:02+00:00

With the restructuring of the lksctp.org site, we only allow bug
reports through the SCTP mailing list linux-sctp@vger.kernel.org,
not via SF, as SF is only used for web hosting and nothing more.
While at it, also remove the obvious statement that bugs will be
fixed and incooperated into the kernel.

Signed-off-by: Daniel Borkmann 
Acked-by: Vlad Yasevich 
Signed-off-by: David S. Miller

sctp: Clean up type-punning in sctp_cmd_t union

2012-11-03T18:54:55+00:00

Lots of points in the sctp_cmd_interpreter function treat the sctp_cmd_t arg as
a void pointer, even though they are written as various other types.  Theres no
need for this as doing so just leads to possible type-punning issues that could
cause crashes, and if we remain type-consistent we can actually just remove the
void * member of the union entirely.

Change Notes:

v2)
	* Dropped chunk that modified SCTP_NULL to create a marker pattern
	 should anyone try to use a SCTP_NULL() assigned sctp_arg_t, Assigning
	 to .zero provides the same effect and should be faster, per Vlad Y.

v3)
	* Reverted part of V2, opting to use memset instead of .zero, so that
	 the entire union is initalized thus avoiding the i164 speculative load
	 problems previously encountered, per Dave M..  Also rewrote
	 SCTP_[NO]FORCE so as to use common infrastructure a little more

Signed-off-by: Neil Horman 
CC: "David S. Miller" 
CC: linux-sctp@vger.kernel.org
Signed-off-by: David S. Miller

sctp: deal with multiple COOKIE_ECHO chunks

2011-09-16T21:17:22+00:00

Attempt to reduce the number of IP packets emitted in response to single
SCTP packet (2e3216cd) introduced a complication - if a packet contains
two COOKIE_ECHO chunks and nothing else then SCTP state machine corks the
socket while processing first COOKIE_ECHO and then loses the association
and forgets to uncork the socket. To deal with the issue add new SCTP
command which can be used to set association explictly. Use this new
command when processing second COOKIE_ECHO chunk to restore the context
for SCTP state machine.

Signed-off-by: Max Matveev 
Signed-off-by: David S. Miller

sctp: Enforce retransmission limit during shutdown

2011-07-07T21:08:44+00:00

When initiating a graceful shutdown while having data chunks
on the retransmission queue with a peer which is in zero
window mode the shutdown is never completed because the
retransmission error count is reset periodically by the
following two rules:

 - Do not timeout association while doing zero window probe.
 - Reset overall error count when a heartbeat request has
   been acknowledged.

The graceful shutdown will wait for all outstanding TSN to
be acknowledged before sending the SHUTDOWN request. This
never happens due to the peer's zero window not acknowledging
the continuously retransmitted data chunks. Although the
error counter is incremented for each failed retransmission,
the receiving of the SACK announcing the zero window clears
the error count again immediately. Also heartbeat requests
continue to be sent periodically. The peer acknowledges these
requests causing the error counter to be reset as well.

This patch changes behaviour to only reset the overall error
counter for the above rules while not in shutdown. After
reaching the maximum number of retransmission attempts, the
T5 shutdown guard timer is scheduled to give the receiver
some additional time to recover. The timer is stopped as soon
as the receiver acknowledges any data.

The issue can be easily reproduced by establishing a sctp
association over the loopback device, constantly queueing
data at the sender while not reading any at the receiver.
Wait for the window to reach zero, then initiate a shutdown
by killing both processes simultaneously. The association
will never be freed and the chunks on the retransmission
queue will be retransmitted indefinitely.

Signed-off-by: Thomas Graf 
Acked-by: Vlad Yasevich 
Signed-off-by: David S. Miller

sctp: stop pending timers and purge queues when peer restart asoc

2011-05-31T22:29:17+00:00

If the peer restart the asoc, we should not only fail any unsent/unacked
data, but also stop the T3-rtx, SACK, T4-rto timers, and teardown ASCONF
queues.

Signed-off-by: Wei Yongjun 
Signed-off-by: David S. Miller