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linux/include/net
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David S. Miller f11e6659ce [IPV6]: Fix routing round-robin locking. 
As per RFC2461, section 6.3.6, item #2, when no routers on the
matching list are known to be reachable or probably reachable we
do round robin on those available routes so that we make sure
to probe as many of them as possible to detect when one becomes
reachable faster.

Each routing table has a rwlock protecting the tree and the linked
list of routes at each leaf.  The round robin code executes during
lookup and thus with the rwlock taken as a reader.  A small local
spinlock tries to provide protection but this does not work at all
for two reasons:

1) The round-robin list manipulation, as coded, goes like this (with
   read lock held):

	walk routes finding head and tail

	spin_lock();
	rotate list using head and tail
	spin_unlock();

   While one thread is rotating the list, another thread can
   end up with stale values of head and tail and then proceed
   to corrupt the list when it gets the lock.  This ends up causing
   the OOPS in fib6_add() later onthat many people have been hitting.

2) All the other code paths that run with the rwlock held as
   a reader do not expect the list to change on them, they
   expect it to remain completely fixed while they hold the
   lock in that way.

So, simply stated, it is impossible to implement this correctly using
a manipulation of the list without violating the rwlock locking
semantics.

Reimplement using a per-fib6_node round-robin pointer.  This way we
don't need to manipulate the list at all, and since the round-robin
pointer can only ever point to real existing entries we don't need
to perform any locking on the changing of the round-robin pointer
itself.  We only need to reset the round-robin pointer to NULL when
the entry it is pointing to is removed.

The idea is from Thomas Graf and it is very similar to how this
was implemented before the advanced router selection code when in.

Signed-off-by: David S. Miller <davem@davemloft.net>
2007-03-25 18:48:05 -07:00
..
bluetooth [PATCH] hci endianness annotations 2006-12-13 09:05:52 -08:00
irda [IRDA] net/irda/: proper prototypes 2007-02-26 11:42:43 -08:00
iucv [S390]: Add AF_IUCV socket support 2007-02-08 13:51:54 -08:00
netfilter [NETFILTER]: conntrack: fix {nf,ip}_ct_iterate_cleanup endless loops 2007-03-05 13:25:18 -08:00
sctp [SCTP]: Reset some transport and association variables on restart 2007-03-20 00:09:45 -07:00
tc_act [PKT_SCHED]: Kill pkt_act.h inlining. 2006-09-22 14:55:10 -07:00
tipc [TIPC]: endianness annotations 2006-12-02 21:21:08 -08:00
act_api.h [PKT_SCHED]: Kill pkt_act.h inlining. 2006-09-22 14:55:10 -07:00
addrconf.h [IPV6]: Misc endianness annotations. 2006-12-02 21:22:52 -08:00
af_unix.h [AF_UNIX]: Kernel memory leak fix for af_unix datagram getpeersec patch 2006-08-02 14:12:06 -07:00
ah.h [IPSEC]: Use HMAC template and hash interface 2006-09-21 11:46:18 +10:00
arp.h [IPV6]: Assorted trivial endianness annotations. 2006-12-02 21:22:50 -08:00
atmclip.h [ATM]: Annotations. 2006-12-02 21:22:55 -08:00
ax25.h [PATCH] mark struct file_operations const 1 2007-02-12 09:48:44 -08:00
checksum.h [NET]: Make mangling a checksum (0 -> 0xffff on the wire) explicit. 2006-12-02 21:23:39 -08:00
cipso_ipv4.h NetLabel: use the correct CIPSOv4 MLS label limits 2006-12-02 21:24:12 -08:00
compat.h Merge git://git.infradead.org/hdrcleanup-2.6 2006-06-20 15:10:08 -07:00
datalink.h [NET]: Kill skb->real_dev 2005-08-29 15:32:25 -07:00
dn_dev.h [DECnet]: Endian annotation and fixes for DECnet. 2006-03-20 22:42:39 -08:00
dn_fib.h [DECNET]: cleanups 2006-09-22 14:54:40 -07:00
dn_neigh.h [DECnet]: Endian annotation and fixes for DECnet. 2006-03-20 22:42:39 -08:00
dn_nsp.h [DECnet]: Endian annotation and fixes for DECnet. 2006-03-20 22:42:39 -08:00
dn_route.h [DECNET]: Convert decnet route to use the new dst_entry 'next' pointer 2007-02-10 23:20:43 -08:00
dn.h [NET]: Reduce sizeof(struct flowi) by 20 bytes. 2006-10-21 20:24:01 -07:00
dsfield.h [NET]: IP header modifier helpers annotations. 2006-12-02 21:23:40 -08:00
dst.h [NET]: Reorder fields of struct dst_entry 2007-02-10 23:20:45 -08:00
esp.h [IPSEC] esp: Defer output IV initialization to first use. 2006-09-22 15:17:35 -07:00
fib_rules.h [NET]: Fix fib_rules compatibility breakage 2007-03-25 18:48:00 -07:00
flow.h [NET]: Rethink mark field in struct flowi 2006-12-02 21:21:39 -08:00
gen_stats.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
genetlink.h [GENETLINK]: Add cmd dump completion. 2006-12-02 21:32:09 -08:00
icmp.h [IPV4]: icmp_send() annotation 2006-09-28 18:01:06 -07:00
ieee80211_crypt.h [PATCH] ieee80211: Add TKIP crypt->build_iv 2006-01-27 17:08:07 -05:00
ieee80211_radiotap.h [PATCH] ieee80211: Added ieee80211_radiotap.h 2005-09-21 23:03:55 -04:00
ieee80211.h [PATCH] ieee80211: WLAN_GET_SEQ_SEQ fix (select correct region) 2007-01-02 20:56:26 -05:00
ieee80211softmac_wx.h [PATCH] softmac: add SIOCSIWMLME 2006-04-24 16:15:58 -04:00
ieee80211softmac.h WorkStruct: make allyesconfig 2006-11-22 14:57:56 +00:00
if_inet6.h [IPV6]: Per-interface statistics support. 2006-12-02 21:22:08 -08:00
inet6_connection_sock.h [TCP]: Restore SKB socket owner setting in tcp_transmit_skb(). 2007-01-26 01:04:55 -08:00
inet6_hashtables.h [IPV6]: annotate inet6_hashtables 2006-12-02 21:21:10 -08:00
inet_common.h [NET]: move struct proto_ops to const 2006-01-03 13:11:15 -08:00
inet_connection_sock.h [TCP]: Restore SKB socket owner setting in tcp_transmit_skb(). 2007-01-26 01:04:55 -08:00
inet_ecn.h [NET]: IP header modifier helpers annotations. 2006-12-02 21:23:40 -08:00
inet_hashtables.h [NET]: change layout of ehash table 2007-02-08 14:16:46 -08:00
inet_sock.h [IPV4]: annotate inet_lookup() and friends 2006-09-28 18:02:26 -07:00
inet_timewait_sock.h [INET]: twcal_jiffie should be unsigned long, not int 2007-03-05 13:32:48 -08:00
inetpeer.h [IPV4] inet_peer: Group together avl_left, avl_right, v4daddr to speedup lookups on some CPUS 2006-10-20 00:28:35 -07:00
ip6_checksum.h [IPV6]: Dumb typo in generic csum_ipv6_magic() 2006-12-22 11:12:07 -08:00
ip6_fib.h [IPV6]: Fix routing round-robin locking. 2007-03-25 18:48:05 -07:00
ip6_route.h [IPV6]: Misc endianness annotations. 2006-12-02 21:22:52 -08:00
ip6_tunnel.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
ip_fib.h [IPV4] nl_fib_lookup: Rename fl_fwmark to fl_mark 2006-12-02 21:21:40 -08:00
ip_mp_alg.h [NET]: Rethink mark field in struct flowi 2006-12-02 21:21:39 -08:00
ip_vs.h [NET]: ipvs checksum annotations. 2006-12-02 21:23:41 -08:00
ip.h [TCP]: Restore SKB socket owner setting in tcp_transmit_skb(). 2007-01-26 01:04:55 -08:00
ipcomp.h [CRYPTO] users: Use crypto_comp and crypto_has_* 2006-09-21 11:46:22 +10:00
ipconfig.h [NET]: ipconfig and nfsroot annotations 2006-12-02 21:21:09 -08:00
ipip.h [IPV6] net/ipv6/sit.c: make 2 functions static 2006-12-02 21:26:15 -08:00
ipv6.h [IPV6]: __ipv6_addr_diff() annotations and cleanup. 2006-12-02 21:22:53 -08:00
ipx.h [IPX]: Annotate and fix IPX checksum 2006-11-05 14:11:25 -08:00
iw_handler.h [PATCH] WE-20 for kernel 2.6.16 2006-03-23 07:12:57 -05:00
lapb.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
llc_c_ac.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
llc_c_ev.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
llc_c_st.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
llc_conn.h [PATCH] gfp flags annotations - part 1 2005-10-08 15:00:57 -07:00
llc_if.h [LLC]: add multicast support for datagrams 2006-06-17 21:26:08 -07:00
llc_pdu.h [LLC]: anotations 2006-12-02 21:21:23 -08:00
llc_s_ac.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
llc_s_ev.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
llc_s_st.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
llc_sap.h [LLC]: Fix the accept path 2005-09-22 07:57:21 -03:00
llc.h [LLC]: llc_mac_hdr_init const arguments 2006-03-20 22:59:36 -08:00
mip6.h [IPV6] MIP6: Add receiving mobility header functions through raw socket. 2006-09-22 15:07:01 -07:00
ndisc.h [IPV6]: Misc endianness annotations. 2006-12-02 21:22:52 -08:00
neighbour.h [NET]: Fix neighbour destructor handling. 2007-03-25 18:48:01 -07:00
netdma.h Remove all inclusions of <linux/config.h> 2006-10-04 03:38:54 -04:00
netevent.h [NET]: Network Event Notifier Mechanism. 2006-08-02 13:38:20 -07:00
netlabel.h NetLabel: convert to an extensibile/sparse category bitmap 2006-12-02 21:31:36 -08:00
netlink.h [PATCH] severing skbuff.h -> mm.h 2006-12-04 02:00:34 -05:00
netrom.h [PATCH] mark struct file_operations const 1 2007-02-12 09:48:44 -08:00
nexthop.h [IPv4]: FIB configuration using struct fib_config 2006-09-22 14:55:04 -07:00
p8022.h [NET]: Fix sparse warnings 2005-08-29 16:01:32 -07:00
pkt_cls.h [NET]: Remove explicit initializations of skb->input_dev 2005-08-29 15:33:26 -07:00
pkt_sched.h [PKT_SCHED]: Fix regression in PSCHED_TADD{,2}. 2006-07-24 12:44:23 -07:00
protocol.h [INET]: Change protocol field in struct inet_protosw to u16 2006-12-02 21:30:55 -08:00
psnap.h [NET]: Kill skb->real_dev 2005-08-29 15:32:25 -07:00
raw.h Merge git://git.infradead.org/hdrcleanup-2.6 2006-06-20 15:10:08 -07:00
rawv6.h [IPV6]: 'info' argument of ipv6 ->err_handler() is net-endian 2006-12-02 21:21:12 -08:00
red.h [PKT_SCHED] RED: Fix overflow in calculation of queue average 2006-08-04 22:59:51 -07:00
request_sock.h [PATCH] slab: remove kmem_cache_t 2006-12-07 08:39:25 -08:00
rose.h [PATCH] mark struct file_operations const 1 2007-02-12 09:48:44 -08:00
route.h [IPV4]: Convert ipv4 route to use the new dst_entry 'next' pointer 2007-02-10 23:20:38 -08:00
sch_generic.h [NET_SCHED]: Fix endless loops caused by inaccurate qlen counters (part 1) 2006-12-02 21:31:42 -08:00
scm.h [AF_UNIX]: Kernel memory leak fix for af_unix datagram getpeersec patch 2006-08-02 14:12:06 -07:00
slhc_vj.h [NET]: Remove __ARGS from include/net/slhc_vj.h 2005-07-05 15:12:04 -07:00
snmp.h [SCTP]: Extend /proc/net/sctp/snmp to provide more statistics. 2006-09-22 14:55:16 -07:00
sock.h [NET]: Revert incorrect accept queue backlog changes. 2007-03-06 11:21:05 -08:00
syncppp.h [PATCH] drivers/net/wan/: possible cleanups 2005-09-14 08:36:54 -04:00
tcp_ecn.h [IPV6]: Added GSO support for TCPv6 2006-06-30 14:12:10 -07:00
tcp_states.h [TCP]: Move the TCPF_ enum to tcp_states.h 2006-01-03 13:10:57 -08:00
tcp.h [TCP]: remove tcp header from tcp_v4_check (take #2) 2007-02-08 12:38:44 -08:00
timewait_sock.h [PATCH] slab: remove kmem_cache_t 2006-12-07 08:39:25 -08:00
transp_v6.h [NET]: Supporting UDP-Lite (RFC 3828) in Linux 2006-12-02 21:22:46 -08:00
udp.h [PATCH] severing skbuff.h -> poll.h 2006-12-04 02:00:31 -05:00
udplite.h [NET]: Fix assorted misannotations (from md5 and udplite merges). 2006-12-02 21:27:16 -08:00
x25.h [X.25]: Adds /proc/sys/net/x25/x25_forward to control forwarding. 2007-02-08 13:34:36 -08:00
x25device.h [X25]: Restore skb->dev setting in x25_type_trans(). 2006-04-09 22:37:18 -07:00
xfrm.h [IPSEC]: xfrm_policy delete security check misplaced 2007-03-07 16:08:09 -08:00