linux-sg2042/include
Thomas Graf f8d9605243 sctp: Enforce retransmission limit during shutdown
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 <tgraf@infradead.org>
Acked-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-07-07 14:08:44 -07:00
..
acpi Merge branches 'acpica', 'aml-custom', 'bugzilla-16548', 'bugzilla-20242', 'd3-cold', 'ec-asus' and 'thermal-fix' into release 2011-05-29 04:38:48 -04:00
asm-generic Merge branches 'gpio/merge' and 'spi/merge' of git://git.secretlab.ca/git/linux-2.6 2011-06-17 10:36:32 -07:00
crypto
drm drm/radeon: workaround a hw bug on some radeon chipsets with all-0 EDIDs. 2011-06-16 16:30:54 +10:00
keys
linux Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2011-07-07 13:22:26 -07:00
math-emu
media [media] m5mols: Use proper email address format 2011-06-11 09:46:00 -03:00
mtd
net sctp: Enforce retransmission limit during shutdown 2011-07-07 14:08:44 -07:00
pcmcia
rdma Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband 2011-05-26 12:13:57 -07:00
rxrpc
scsi [SCSI] libsas: Add option for SATA soft reset 2011-05-26 22:49:33 -05:00
sound ALSA: sb16 - Fix build errors on MIPS and others with 13bit ioctl size 2011-06-30 15:33:57 +02:00
target [SCSI] target: Convert REPORT_LUNs to use int_to_scsilun 2011-05-24 13:02:42 -04:00
trace Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2011-06-21 10:22:35 -07:00
video Merge branches 'common/fbdev' and 'common/fbdev-meram' of master.kernel.org:/pub/scm/linux/kernel/git/lethal/sh-2.6 2011-05-24 15:49:57 +09:00
xen Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/djm/tmem 2011-05-26 10:50:56 -07:00
Kbuild