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linux-2.6/net
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Daniel J Blueman 4f919a3bc5 fix cfg80211_wext_siwfreq lock ordering... 
I previously managed to reproduce a hang while scanning wireless
channels (reproducible with airodump-ng hopping channels); subsequent
lockdep instrumentation revealed a lock ordering issue.

Without knowing the design intent, it looks like the locks should be
taken in reverse order; please comment.

=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.38-rc5-341cd #4
-------------------------------------------------------
airodump-ng/15445 is trying to acquire lock:
 (&rdev->devlist_mtx){+.+.+.}, at: [<ffffffff816b1266>]
cfg80211_wext_siwfreq+0xc6/0x100

but task is already holding lock:
 (&wdev->mtx){+.+.+.}, at: [<ffffffff816b125c>] cfg80211_wext_siwfreq+0xbc/0x100

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&wdev->mtx){+.+.+.}:
       [<ffffffff810a79d6>] lock_acquire+0xc6/0x280
       [<ffffffff816d6bce>] mutex_lock_nested+0x6e/0x4b0
       [<ffffffff81696080>] cfg80211_netdev_notifier_call+0x430/0x5f0
       [<ffffffff8109351b>] notifier_call_chain+0x8b/0x100
       [<ffffffff810935b1>] raw_notifier_call_chain+0x11/0x20
       [<ffffffff81576d92>] call_netdevice_notifiers+0x32/0x60
       [<ffffffff815771a4>] __dev_notify_flags+0x34/0x80
       [<ffffffff81577230>] dev_change_flags+0x40/0x70
       [<ffffffff8158587c>] do_setlink+0x1fc/0x8d0
       [<ffffffff81586042>] rtnl_setlink+0xf2/0x140
       [<ffffffff81586923>] rtnetlink_rcv_msg+0x163/0x270
       [<ffffffff8159d741>] netlink_rcv_skb+0xa1/0xd0
       [<ffffffff815867b0>] rtnetlink_rcv+0x20/0x30
       [<ffffffff8159d39a>] netlink_unicast+0x2ba/0x300
       [<ffffffff8159dd57>] netlink_sendmsg+0x267/0x3e0
       [<ffffffff8155e364>] sock_sendmsg+0xe4/0x110
       [<ffffffff8155f3a3>] sys_sendmsg+0x253/0x3b0
       [<ffffffff81003192>] system_call_fastpath+0x16/0x1b

-> #0 (&rdev->devlist_mtx){+.+.+.}:
       [<ffffffff810a7222>] __lock_acquire+0x1622/0x1d10
       [<ffffffff810a79d6>] lock_acquire+0xc6/0x280
       [<ffffffff816d6bce>] mutex_lock_nested+0x6e/0x4b0
       [<ffffffff816b1266>] cfg80211_wext_siwfreq+0xc6/0x100
       [<ffffffff816b2fad>] ioctl_standard_call+0x5d/0xd0
       [<ffffffff816b3223>] T.808+0x163/0x170
       [<ffffffff816b326a>] wext_handle_ioctl+0x3a/0x90
       [<ffffffff815798d2>] dev_ioctl+0x6f2/0x830
       [<ffffffff8155cf3d>] sock_ioctl+0xfd/0x290
       [<ffffffff8117dffd>] do_vfs_ioctl+0x9d/0x590
       [<ffffffff8117e53a>] sys_ioctl+0x4a/0x80
       [<ffffffff81003192>] system_call_fastpath+0x16/0x1b

other info that might help us debug this:

2 locks held by airodump-ng/15445:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff81586782>] rtnl_lock+0x12/0x20
 #1:  (&wdev->mtx){+.+.+.}, at: [<ffffffff816b125c>]
cfg80211_wext_siwfreq+0xbc/0x100

stack backtrace:
Pid: 15445, comm: airodump-ng Not tainted 2.6.38-rc5-341cd #4
Call Trace:
 [<ffffffff810a3f0a>] ? print_circular_bug+0xfa/0x100
 [<ffffffff810a7222>] ? __lock_acquire+0x1622/0x1d10
 [<ffffffff810a1f99>] ? trace_hardirqs_off_caller+0x29/0xc0
 [<ffffffff810a79d6>] ? lock_acquire+0xc6/0x280
 [<ffffffff816b1266>] ? cfg80211_wext_siwfreq+0xc6/0x100
 [<ffffffff810a31d7>] ? mark_held_locks+0x67/0x90
 [<ffffffff816d6bce>] ? mutex_lock_nested+0x6e/0x4b0
 [<ffffffff816b1266>] ? cfg80211_wext_siwfreq+0xc6/0x100
 [<ffffffff810a31d7>] ? mark_held_locks+0x67/0x90
 [<ffffffff816b1266>] ? cfg80211_wext_siwfreq+0xc6/0x100
 [<ffffffff816b1266>] ? cfg80211_wext_siwfreq+0xc6/0x100
 [<ffffffff816b2fad>] ? ioctl_standard_call+0x5d/0xd0
 [<ffffffff8157818b>] ? __dev_get_by_name+0x9b/0xc0
 [<ffffffff816b2f50>] ? ioctl_standard_call+0x0/0xd0
 [<ffffffff816b3223>] ? T.808+0x163/0x170
 [<ffffffff8112ddf2>] ? might_fault+0x72/0xd0
 [<ffffffff816b326a>] ? wext_handle_ioctl+0x3a/0x90
 [<ffffffff8112de3b>] ? might_fault+0xbb/0xd0
 [<ffffffff815798d2>] ? dev_ioctl+0x6f2/0x830
 [<ffffffff810a1bae>] ? put_lock_stats+0xe/0x40
 [<ffffffff810a1c8c>] ? lock_release_holdtime+0xac/0x150
 [<ffffffff8155cf3d>] ? sock_ioctl+0xfd/0x290
 [<ffffffff8117dffd>] ? do_vfs_ioctl+0x9d/0x590
 [<ffffffff8116c8ff>] ? fget_light+0x1df/0x3c0
 [<ffffffff8117e53a>] ? sys_ioctl+0x4a/0x80
 [<ffffffff81003192>] ? system_call_fastpath+0x16/0x1b

Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
 		2011-02-21 15:14:25 -05:00
..
9p net/9p/protocol.c: Remove duplicated macros. 2010-12-08 09:56:28 -08:00
802 net/802: add __rcu annotations 2010-10-25 13:09:44 -07:00
8021q 8021q: vlan device is lockless do not transfer real_num_{tx|rx}_queues 2010-11-28 10:47:19 -08:00
appletalk Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-04-11 14:53:53 -07:00
atm Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2011-01-07 16:58:04 -08:00
ax25 net: ax25: fix information leak to userland 2010-11-10 10:14:33 -08:00
batman-adv batman-adv: Return hna count on local buffer fill 2010-12-20 10:32:03 -08:00
bluetooth Bluetooth: Release BTM while sleeping to avoid deadlock 2011-02-16 15:54:11 -03:00
bridge net: bridge: check the length of skb after nf_bridge_maybe_copy_header() 2011-01-06 11:33:05 -08:00
caif Net: caif: Makefile: Remove deprecated items 2010-11-22 08:16:09 -08:00
can Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-01-04 11:57:25 -08:00
ceph Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-12-26 22:37:05 -08:00
core net offloading: Convert checksums to use centrally computed features. 2011-01-09 23:35:35 -08:00
dcb dcb: use after free in dcb_flushapp() 2011-01-06 11:16:54 -08:00
dccp dccp: make upper bound for seq_window consistent on 32/64 bit 2011-01-07 12:22:44 +01:00
decnet net: Abstract default MTU metric calculation behind an accessor. 2010-12-14 13:01:14 -08:00
dns_resolver Net: dns_resolver: Makefile: Remove deprecated kbuild goal definitions 2010-11-22 08:16:10 -08:00
dsa net/dsa: don't use flush_scheduled_work() 2010-12-24 15:59:06 +01:00
econet Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-12-17 12:27:22 -08:00
ethernet net: return operator cleanup 2010-09-23 14:33:39 -07:00
ieee802154 net: RCU conversion of dev_getbyhwaddr() and arp_ioctl() 2010-12-08 10:07:24 -08:00
ipv4 netlink: test for all flags of the NLM_F_DUMP composite 2011-01-09 16:25:03 -08:00
ipv6 Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-12-20 13:24:14 -08:00
ipx BKL: introduce CONFIG_BKL. 2010-10-21 15:44:13 +02:00
irda Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-12-26 22:37:05 -08:00
iucv [S390] irq: have detailed statistics for interrupt types 2011-01-05 12:47:25 +01:00
key net: return operator cleanup 2010-09-23 14:33:39 -07:00
l2tp Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-12-08 13:47:38 -08:00
lapb Net: lapb: Makefile: Remove deprecated kbuild goal definitions 2010-11-22 08:16:14 -08:00
llc net: RCU conversion of dev_getbyhwaddr() and arp_ioctl() 2010-12-08 10:07:24 -08:00
mac80211 mac80211: fix conn_mon_timer running after disassociate 2011-02-18 16:47:37 -05:00
netfilter netlink: test for all flags of the NLM_F_DUMP composite 2011-01-09 16:25:03 -08:00
netlabel net: kill unused macros 2010-12-19 21:59:35 -08:00
netlink netlink: test for all flags of the NLM_F_DUMP composite 2011-01-09 16:25:03 -08:00
netrom net: sk_sleep() helper 2010-04-20 16:37:13 -07:00
packet net: Use skb_checksum_start_offset() 2010-12-16 14:43:14 -08:00
phonet Net: phonet: Makefile: Remove deprecated kbuild goal definitions 2010-11-22 08:16:14 -08:00
rds Net: rds: Makefile: Remove deprecated items 2010-11-22 08:16:15 -08:00
rfkill rfkill: remove dead code 2010-11-15 13:24:06 -05:00
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 Net: rxrpc: Makefile: Remove deprecated kbuild goal definitions 2010-11-22 08:16:15 -08:00
sched net_sched: pfifo_head_drop problem 2011-01-05 13:39:17 -08:00
sctp Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-12-17 12:27:22 -08:00
sunrpc Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2011-01-07 16:58:04 -08:00
tipc tipc: update log.h re-include protection to reflect new name 2011-01-01 14:56:18 -08:00
unix af_unix: Avoid socket->sk NULL OOPS in stream connect security hooks. 2011-01-05 15:38:53 -08:00
wanrouter Net: wanrouter: Makefile: Remove deprecated kbuild goal definitions 2010-11-22 08:16:16 -08:00
wimax Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2010-05-20 21:04:44 -07:00
wireless fix cfg80211_wext_siwfreq lock ordering... 2011-02-21 15:14:25 -05:00
x25 Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-12-08 13:47:38 -08:00
xfrm netlink: test for all flags of the NLM_F_DUMP composite 2011-01-09 16:25:03 -08:00
Kconfig net: Add batman-adv meshing protocol 2010-12-16 13:44:24 -08:00
Makefile net: Add batman-adv meshing protocol 2010-12-16 13:44:24 -08:00
TUNABLE
…
compat.c net: Limit socket I/O iovec total length to INT_MAX. 2010-10-28 11:47:52 -07:00
nonet.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
socket.c Merge branch 'vfs-scale-working' of git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin 2011-01-07 08:56:33 -08:00
sysctl_net.c net: Remove unnecessary returns from void function()s 2010-05-17 23:23:14 -07:00