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5e016cbf6c
tmp_suning_uos_patched/net/ipv4
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Guenter Roeck 5e016cbf6c ipv4: Don't drop redirected route cache entry unless PTMU actually expired 
TCP sessions over IPv4 can get stuck if routers between endpoints
do not fragment packets but implement PMTU instead, and we are using
those routers because of an ICMP redirect.

Setup is as follows

       MTU1    MTU2   MTU1
    A--------B------C------D

with MTU1 > MTU2. A and D are endpoints, B and C are routers. B and C
implement PMTU and drop packets larger than MTU2 (for example because
DF is set on all packets). TCP sessions are initiated between A and D.
There is packet loss between A and D, causing frequent TCP
retransmits.

After the number of retransmits on a TCP session reaches tcp_retries1,
tcp calls dst_negative_advice() prior to each retransmit. This results
in route cache entries for the peer to be deleted in
ipv4_negative_advice() if the Path MTU is set.

If the outstanding data on an affected TCP session is larger than
MTU2, packets sent from the endpoints will be dropped by B or C, and
ICMP NEEDFRAG will be returned. A and D receive NEEDFRAG messages and
update PMTU.

Before the next retransmit, tcp will again call dst_negative_advice(),
causing the route cache entry (with correct PMTU) to be deleted. The
retransmitted packet will be larger than MTU2, causing it to be
dropped again.

This sequence repeats until the TCP session aborts or is terminated.

Problem is fixed by removing redirected route cache entries in
ipv4_negative_advice() only if the PMTU is expired.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-03-21 20:55:13 -07:00
..
netfilter netfilter: xtables: restore indentation 2010-02-26 17:53:31 +01:00
af_inet.c percpu: add __percpu sparse annotations to net 2010-02-16 23:05:38 -08:00
ah4.c xfrm: SA lookups signature with mark 2010-02-22 16:20:22 -08:00
arp.c net neigh: Decouple per interface neighbour table controls from binary sysctls 2010-02-16 15:55:18 -08:00
cipso_ipv4.c ipv4: Define cipso_v4_delopt static 2009-10-07 14:45:58 -07:00
datagram.c inet: rename some inet_sock fields 2009-10-18 18:52:53 -07:00
devinet.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-02-25 23:22:42 -08:00
esp4.c xfrm: SA lookups signature with mark 2010-02-22 16:20:22 -08:00
fib_frontend.c net: spread __net_init, __net_exit 2010-01-17 19:16:02 -08:00
fib_hash.c ipv4: fib table algorithm performance improvement 2009-10-05 00:21:56 -07:00
fib_lookup.h ipv4: cleanup - remove two unused parameters from fib_semantic_match(). 2009-05-18 15:16:37 -07:00
fib_rules.c net: Allow fib_rule_unregister to batch 2009-12-03 12:22:55 -08:00
fib_semantics.c ipv4: obsolete config in kernel source (IP_ROUTE_PERVASIVE) 2010-02-04 14:58:46 -08:00
fib_trie.c net: suppress lockdep-RCU false positive in FIB trie. 2010-03-21 18:01:05 -07:00
icmp.c icmp: move icmp_err_convert[] to .rodata 2010-01-23 01:21:28 -08:00
igmp.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-02-14 22:30:54 -08:00
inet_connection_sock.c tcp: account SYN-ACK timeouts & retransmissions 2010-01-17 19:09:39 -08:00
inet_diag.c netlink: With opcode INET_DIAG_BC_S_LE dport was compared in inet_diag_bc_run() 2010-01-19 14:12:20 -08:00
inet_fragment.c inet fragments: fix sparse warning: context imbalance 2009-02-26 23:13:35 -08:00
inet_hashtables.c tcp: Fix a connect() race with timewait sockets 2009-12-08 20:17:51 -08:00
inet_lro.c net/ipv4: Move && and || to end of previous line 2009-11-23 10:41:23 -08:00
inet_timewait_sock.c [PATCH] tcp: documents timewait refcnt tricks 2009-12-08 20:19:53 -08:00
inetpeer.c inetpeer: Optimize inet_getid() 2009-11-13 20:46:58 -08:00
ip_forward.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
ip_fragment.c ipv4: ip_fragment: fix unbalanced rcu_read_unlock() 2010-02-02 11:46:50 -08:00
ip_gre.c gre: fix hard header destination address checking 2010-03-04 00:53:52 -08:00
ip_input.c net: use net_eq to compare nets 2009-11-25 15:14:13 -08:00
ip_options.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
ip_output.c ip: fix mc_loop checks for tunnels with multicast outer addresses 2010-01-06 20:37:01 -08:00
ip_sockglue.c tcp: Generalized TTL Security Mechanism 2010-01-11 16:28:01 -08:00
ipcomp.c xfrm: SA lookups signature with mark 2010-02-22 16:20:22 -08:00
ipconfig.c ipconfig: Handle devices which take some time to come up. 2010-03-12 00:00:17 -08:00
ipip.c tunnels: fix netns vs proto registration ordering 2010-02-16 14:55:25 -08:00
ipmr.c net: ipmr/ip6mr: fix potential out-of-bounds vif_table access 2010-03-19 22:47:22 -07:00
Kconfig nfs: new subdir Documentation/filesystems/nfs 2009-10-27 19:34:04 -04:00
Makefile IPVS: Move IPVS to net/netfilter/ipvs 2008-10-07 08:38:24 +11:00
netfilter.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2009-12-08 07:55:01 -08:00
proc.c tcp: Add SNMP counters for backlog and min_ttl drops 2010-03-08 10:45:27 -08:00
protocol.c net: constify struct net_protocol 2009-09-14 17:03:01 -07:00
raw.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2009-10-29 21:28:59 -07:00
route.c ipv4: Don't drop redirected route cache entry unless PTMU actually expired 2010-03-21 20:55:13 -07:00
syncookies.c net: Add rtnetlink init_rcvwnd to set the TCP initial receive window 2009-12-23 14:13:30 -08:00
sysctl_net_ipv4.c net: TCP thin dupack 2010-02-18 15:43:09 -08:00
tcp_bic.c tcp: add helper for AI algorithm 2009-03-02 03:00:15 -08:00
tcp_cong.c Networking: use CAP_NET_ADMIN when deciding to call request_module 2009-08-14 11:18:34 +10:00
tcp_cubic.c tcp: add helper for AI algorithm 2009-03-02 03:00:15 -08:00
tcp_diag.c tcp: diag: Dont report negative values for rx queue 2009-12-03 16:06:13 -08:00
tcp_highspeed.c
tcp_htcp.c net/ipv4: Move && and || to end of previous line 2009-11-23 10:41:23 -08:00
tcp_hybla.c tcp: Fix tcp_hybla zero congestion window growth with small rho and large cwnd. 2008-10-07 15:58:17 -07:00
tcp_illinois.c
tcp_input.c tcp: Fix tcp_mark_head_lost() with packets == 0 2010-03-19 22:47:22 -07:00
tcp_ipv4.c TCP: check min TTL on received ICMP packets 2010-03-19 21:00:42 -07:00
tcp_lp.c net/ipv4: Move && and || to end of previous line 2009-11-23 10:41:23 -08:00
tcp_minisocks.c net: backlog functions rename 2010-03-05 13:34:03 -08:00
tcp_output.c tcp: Fix tcp_make_synack() 2010-03-08 11:32:01 -08:00
tcp_probe.c tcp_probe: avoid modulus operation and wrap fix 2010-01-25 15:47:50 -08:00
tcp_scalable.c tcp: add helper for AI algorithm 2009-03-02 03:00:15 -08:00
tcp_timer.c Merge branch 'for-next' into for-linus 2010-03-08 16:55:37 +01:00
tcp_vegas.c tcp: tcp_vegas ssthresh bugfix 2009-05-25 22:44:59 -07:00
tcp_vegas.h
tcp_veno.c net/ipv4: Move && and || to end of previous line 2009-11-23 10:41:23 -08:00
tcp_westwood.c
tcp_yeah.c net/ipv4: Move && and || to end of previous line 2009-11-23 10:41:23 -08:00
tcp.c NET_DMA: free skbs periodically 2010-03-20 14:29:02 -07:00
tunnel4.c net: constify struct net_protocol 2009-09-14 17:03:01 -07:00
udp_impl.h net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
udp.c net: backlog functions rename 2010-03-05 13:34:03 -08:00
udplite.c net: spread __net_init, __net_exit 2010-01-17 19:16:02 -08:00
xfrm4_input.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
xfrm4_mode_beet.c ipsec: Interfamily IPSec BEET 2008-08-06 02:39:30 -07:00
xfrm4_mode_transport.c
xfrm4_mode_tunnel.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
xfrm4_output.c net: skb->dst accessors 2009-06-03 02:51:04 -07:00
xfrm4_policy.c ipsec: Fix bogus bundle flowi 2010-03-03 01:04:37 -08:00
xfrm4_state.c xfrm: remove useless forward declarations 2008-11-25 01:05:54 -08:00
xfrm4_tunnel.c