linux/net
Gerrit Renker b1fcf55eea dccp: Refine the wait-for-ccid mechanism
This extends the existing wait-for-ccid routine so that it may be used with
different types of CCID, addressing the following problems:

 1) The queue-drain mechanism only works with rate-based CCIDs. If CCID-2 for
    example has a full TX queue and becomes network-limited just as the
    application wants to close, then waiting for CCID-2 to become unblocked
    could lead to an indefinite  delay (i.e., application "hangs").
 2) Since each TX CCID in turn uses a feedback mechanism, there may be changes
    in its sending policy while the queue is being drained. This can lead to
    further delays during which the application will not be able to terminate.
 3) The minimum wait time for CCID-3/4 can be expected to be the queue length
    times the current inter-packet delay. For example if tx_qlen=100 and a delay
    of 15 ms is used for each packet, then the application would have to wait
    for a minimum of 1.5 seconds before being allowed to exit.
 4) There is no way for the user/application to control this behaviour. It would
    be good to use the timeout argument of dccp_close() as an upper bound. Then
    the maximum time that an application is willing to wait for its CCIDs to can
    be set via the SO_LINGER option.

These problems are addressed by giving the CCID a grace period of up to the
`timeout' value.

The wait-for-ccid function is, as before, used when the application
 (a) has read all the data in its receive buffer and
 (b) if SO_LINGER was set with a non-zero linger time, or
 (c) the socket is either in the OPEN (active close) or in the PASSIVE_CLOSEREQ
     state (client application closes after receiving CloseReq).

In addition, there is a catch-all case of __skb_queue_purge() after waiting for
the CCID. This is necessary since the write queue may still have data when
 (a) the host has been passively-closed,
 (b) abnormal termination (unread data, zero linger time),
 (c) wait-for-ccid could not finish within the given time limit.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-10-28 10:27:01 -07:00
..
9p 9p: client code cleanup 2010-10-21 04:26:39 -07:00
802 net/802: add __rcu annotations 2010-10-25 13:09:44 -07:00
8021q vlan: rcu annotations 2010-10-25 13:09:43 -07:00
appletalk
atm Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2010-10-23 11:47:02 -07:00
ax25 Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2010-10-24 13:41:39 -07:00
bluetooth Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2010-10-23 11:47:02 -07:00
bridge bridge: Forward reserved group addresses if !STP 2010-10-21 04:25:48 -07:00
caif Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-10-06 19:39:31 -07:00
can can-raw: add msg_flags to distinguish local traffic 2010-10-21 04:27:03 -07:00
ceph ceph: fix num_pages_free accounting in pagelist 2010-10-20 15:38:23 -07:00
core fib_rules: __rcu annotates ctarget 2010-10-27 11:37:32 -07:00
dcb
dccp dccp: Refine the wait-for-ccid mechanism 2010-10-28 10:27:01 -07:00
decnet net dst: use a percpu_counter to track entries 2010-10-11 13:06:53 -07:00
dns_resolver DNS: If the DNS server returns an error, allow that to be cached [ver #2] 2010-08-11 17:11:28 +00:00
dsa phylib: available for any speed ethernet 2010-08-11 23:03:50 -07:00
econet net: return operator cleanup 2010-09-23 14:33:39 -07:00
ethernet net: return operator cleanup 2010-09-23 14:33:39 -07:00
ieee802154
ipv4 tunnels: Fix tunnels change rcu protection 2010-10-27 14:20:08 -07:00
ipv6 tunnels: Fix tunnels change rcu protection 2010-10-27 14:20:08 -07:00
ipx BKL: introduce CONFIG_BKL. 2010-10-21 15:44:13 +02:00
irda Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2010-10-24 13:41:39 -07:00
iucv
key net: return operator cleanup 2010-09-23 14:33:39 -07:00
l2tp l2tp: static functions should not be exported 2010-10-24 22:26:41 -07:00
lapb
llc net/llc: storing negative error codes in unsigned short 2010-09-16 22:38:23 -07:00
mac80211 mac80211: Fix ibss station got expired immediately 2010-10-25 14:45:56 -04:00
netfilter netfilter: fix module dependency issues with IPv6 defragmentation, ip6tables and xt_TPROXY 2010-10-25 13:58:36 -07:00
netlabel
netlink netlink: fix netlink_change_ngroups() 2010-10-24 16:25:39 -07:00
netrom
packet net: simplify flags for tx timestamping 2010-08-19 00:08:30 -07:00
phonet phonet: remove the unused variable pn 2010-10-20 01:55:54 -07:00
rds Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-10-21 08:43:05 -07:00
rfkill Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2010-10-23 11:47:02 -07:00
rose Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-09-27 01:03:03 -07:00
rxrpc Add a dummy printk function for the maintenance of unused printks 2010-08-12 09:51:35 -07:00
sched Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2010-10-23 11:47:02 -07:00
sctp Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2010-10-23 11:47:02 -07:00
sunrpc Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2010-10-24 13:41:39 -07:00
tipc Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-10-21 08:43:05 -07:00
unix AF_UNIX: Implement SO_TIMESTAMP and SO_TIMETAMPNS on Unix sockets 2010-10-05 14:54:36 -07:00
wanrouter fix printk typo 'faild' 2010-08-09 11:25:17 +02:00
wimax
wireless cfg80211: fix regression on processing country IEs 2010-10-25 14:43:14 -04:00
x25 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2010-10-23 11:47:02 -07:00
xfrm xfrm: make xfrm_bundle_ok local 2010-10-21 03:09:46 -07:00
compat.c
Kconfig ceph: factor out libceph from Ceph file system 2010-10-20 15:37:28 -07:00
Makefile ceph: factor out libceph from Ceph file system 2010-10-20 15:37:28 -07:00
nonet.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
socket.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2010-10-23 11:47:02 -07:00
sysctl_net.c
TUNABLE