linux-toradex.git/net/sctp/sm_statetable.c, branch v3.0.77

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: implement event notification SCTP_SENDER_DRY_EVENT

2011-04-21T17:35:44+00:00

This patch implement event notification SCTP_SENDER_DRY_EVENT.
SCTP Socket API Extensions:

  6.1.9. SCTP_SENDER_DRY_EVENT

  When the SCTP stack has no more user data to send or retransmit, this
  notification is given to the user. Also, at the time when a user app
  subscribes to this event, if there is no data to be sent or
  retransmit, the stack will immediately send up this notification.

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

sctp: remove completely unsed EMPTY state

2011-04-20T08:51:03+00:00

SCTP does not SCTP_STATE_EMPTY and we can never be in
that state.  Remove useless code.

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

net/sctp: Use pr_fmt and pr_

2010-08-26T21:11:48+00:00

Change SCTP_DEBUG_PRINTK and SCTP_DEBUG_PRINTK_IPADDR to
use do { print } while (0) guards.
Add SCTP_DEBUG_PRINTK_CONT to fix errors in log when
lines were continued.
Add #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
Add a missing newline in "Failed bind hash alloc"

Signed-off-by: Joe Perches 
Signed-off-by: David S. Miller

sctp: fix a typo in net/sctp/sm_statetable.c

2009-06-03T13:14:45+00:00

Just fix a typo in net/sctp/sm_statetable.c.

Signed-off-by: Wei Yongjun 
Signed-off-by: Vlad Yasevich

sctp: Fix to handle SHUTDOWN in SHUTDOWN_RECEIVED state

2008-10-23T08:01:18+00:00

Once an endpoint has reached the SHUTDOWN-RECEIVED state,
it MUST NOT send a SHUTDOWN in response to a ULP request.
The Cumulative TSN Ack of the received SHUTDOWN chunk
MUST be processed.

This patch fix to process Cumulative TSN Ack of the received
SHUTDOWN chunk in SHUTDOWN_RECEIVED state.

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

sctp: Fix to handle SHUTDOWN in SHUTDOWN-PENDING state

2008-10-23T08:00:49+00:00

If SHUTDOWN is received in SHUTDOWN-PENDING state, enpoint should enter
the SHUTDOWN-RECEIVED state and check the Cumulative TSN Ack field of
the SHUTDOWN chunk (RFC 4960 Section 9.2). If the SHUTDOWN chunk can
acknowledge all of the send DATA chunks, SHUTDOWN-ACK should be sent.

But now endpoint just silently discarded the SHUTDOWN chunk.

SHUTDOWN received in SHUTDOWN-PENDING state can happend when the last
SACK is lost by network, or the SHUTDOWN chunk can acknowledge all of
the received DATA chunks. The packet sequence(SACK lost) is like this:

Endpoint A                       Endpoint B       ULP
(ESTABLISHED)                    (ESTABLISHED)

               <-----------      DATA
                                             <--- shutdown
                                 Enter SHUTDOWN-PENDING state
  SACK         ----lost---->

  SHUTDOWN(*1) ------------>

               <-----------      SHUTDOWN-ACK

 (*1) silently discarded now.

This patch fix to handle SHUTDOWN in SHUTDOWN-PENDING state as the same
as ESTABLISHED state.

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

sctp: Fix to start T5-shutdown-guard timer while enter SHUTDOWN-SENT state

2008-10-01T15:34:16+00:00

RFC 4960: Section 9.2
The sender of the SHUTDOWN MAY also start an overall guard timer
'T5-shutdown-guard' to bound the overall time for the shutdown
sequence.  At the expiration of this timer, the sender SHOULD abort
the association by sending an ABORT chunk.  If the 'T5-shutdown-
guard' timer is used, it SHOULD be set to the recommended value of 5
times 'RTO.Max'.

The timer 'T5-shutdown-guard' is used to counter the overall time
for shutdown sequence, and it's start by the sender of the SHUTDOWN.
So timer 'T5-shutdown-guard' should be start when we send the first
SHUTDOWN chunk and enter the SHUTDOWN-SENT state, not start when we
receipt of the SHUTDOWN primitive and enter SHUTDOWN-PENDING state.

If 'T5-shutdown-guard' timer is start at SHUTDOWN-PENDING state, the
association may be ABORT while data is still transmitting.

Signed-off-by: Wei Yongjun 
Signed-off-by: Vlad Yasevich

[SCTP]: Stop claiming that this is a "reference implementation"

2008-02-05T15:59:07+00:00

I was notified by Randy Stewart that lksctp claims to be
"the reference implementation".  First of all, "the
refrence implementation" was the original implementation
of SCTP in usersapce written ty Randy and a few others.
Second, after looking at the definiton of 'reference implementation',
we don't really meet the requirements.

Signed-off-by: Vlad Yasevich

[SCTP]: ADD-IP updates the states where ASCONFs can be sent

2008-01-28T22:59:22+00:00

   C4)  Both ASCONF and ASCONF-ACK Chunks MUST NOT be sent in any SCTP
        state except ESTABLISHED, SHUTDOWN-PENDING, SHUTDOWN-RECEIVED,
        and SHUTDOWN-SENT.

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