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Andre Guedes a51cd2be86 Bluetooth: Fix potential deadlock 
We don't need to use the _sync variant in hci_conn_hold and
hci_conn_put to cancel conn->disc_work delayed work. This way
we avoid potential deadlocks like this one reported by lockdep.

======================================================
[ INFO: possible circular locking dependency detected ]
3.2.0+ #1 Not tainted
-------------------------------------------------------
kworker/u:1/17 is trying to acquire lock:
 (&hdev->lock){+.+.+.}, at: [<ffffffffa0041155>] hci_conn_timeout+0x62/0x158 [bluetooth]

but task is already holding lock:
 ((&(&conn->disc_work)->work)){+.+...}, at: [<ffffffff81035751>] process_one_work+0x11a/0x2bf

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 ((&(&conn->disc_work)->work)){+.+...}:
       [<ffffffff81057444>] lock_acquire+0x8a/0xa7
       [<ffffffff81034ed1>] wait_on_work+0x3d/0xaa
       [<ffffffff81035b54>] __cancel_work_timer+0xac/0xef
       [<ffffffff81035ba4>] cancel_delayed_work_sync+0xd/0xf
       [<ffffffffa00554b0>] smp_chan_create+0xde/0xe6 [bluetooth]
       [<ffffffffa0056160>] smp_conn_security+0xa3/0x12d [bluetooth]
       [<ffffffffa0053640>] l2cap_connect_cfm+0x237/0x2e8 [bluetooth]
       [<ffffffffa004239c>] hci_proto_connect_cfm+0x2d/0x6f [bluetooth]
       [<ffffffffa0046ea5>] hci_event_packet+0x29d1/0x2d60 [bluetooth]
       [<ffffffffa003dde3>] hci_rx_work+0xd0/0x2e1 [bluetooth]
       [<ffffffff810357af>] process_one_work+0x178/0x2bf
       [<ffffffff81036178>] worker_thread+0xce/0x152
       [<ffffffff81039a03>] kthread+0x95/0x9d
       [<ffffffff812e7754>] kernel_thread_helper+0x4/0x10

-> #1 (slock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+...}:
       [<ffffffff81057444>] lock_acquire+0x8a/0xa7
       [<ffffffff812e553a>] _raw_spin_lock_bh+0x36/0x6a
       [<ffffffff81244d56>] lock_sock_nested+0x24/0x7f
       [<ffffffffa004d96f>] lock_sock+0xb/0xd [bluetooth]
       [<ffffffffa0052906>] l2cap_chan_connect+0xa9/0x26f [bluetooth]
       [<ffffffffa00545f8>] l2cap_sock_connect+0xb3/0xff [bluetooth]
       [<ffffffff81243b48>] sys_connect+0x69/0x8a
       [<ffffffff812e6579>] system_call_fastpath+0x16/0x1b

-> #0 (&hdev->lock){+.+.+.}:
       [<ffffffff81056d06>] __lock_acquire+0xa80/0xd74
       [<ffffffff81057444>] lock_acquire+0x8a/0xa7
       [<ffffffff812e3870>] __mutex_lock_common+0x48/0x38e
       [<ffffffff812e3c75>] mutex_lock_nested+0x2a/0x31
       [<ffffffffa0041155>] hci_conn_timeout+0x62/0x158 [bluetooth]
       [<ffffffff810357af>] process_one_work+0x178/0x2bf
       [<ffffffff81036178>] worker_thread+0xce/0x152
       [<ffffffff81039a03>] kthread+0x95/0x9d
       [<ffffffff812e7754>] kernel_thread_helper+0x4/0x10

other info that might help us debug this:

Chain exists of:
  &hdev->lock --> slock-AF_BLUETOOTH-BTPROTO_L2CAP --> (&(&conn->disc_work)->work)

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock((&(&conn->disc_work)->work));
                               lock(slock-AF_BLUETOOTH-BTPROTO_L2CAP);
                               lock((&(&conn->disc_work)->work));
  lock(&hdev->lock);

 *** DEADLOCK ***

2 locks held by kworker/u:1/17:
 #0:  (hdev->name){.+.+.+}, at: [<ffffffff81035751>] process_one_work+0x11a/0x2bf
 #1:  ((&(&conn->disc_work)->work)){+.+...}, at: [<ffffffff81035751>] process_one_work+0x11a/0x2bf

stack backtrace:
Pid: 17, comm: kworker/u:1 Not tainted 3.2.0+ #1
Call Trace:
 [<ffffffff812e06c6>] print_circular_bug+0x1f8/0x209
 [<ffffffff81056d06>] __lock_acquire+0xa80/0xd74
 [<ffffffff81021ef2>] ? arch_local_irq_restore+0x6/0xd
 [<ffffffff81022bc7>] ? vprintk+0x3f9/0x41e
 [<ffffffff81057444>] lock_acquire+0x8a/0xa7
 [<ffffffffa0041155>] ? hci_conn_timeout+0x62/0x158 [bluetooth]
 [<ffffffff812e3870>] __mutex_lock_common+0x48/0x38e
 [<ffffffffa0041155>] ? hci_conn_timeout+0x62/0x158 [bluetooth]
 [<ffffffff81190fd6>] ? __dynamic_pr_debug+0x6d/0x6f
 [<ffffffffa0041155>] ? hci_conn_timeout+0x62/0x158 [bluetooth]
 [<ffffffff8105320f>] ? trace_hardirqs_off+0xd/0xf
 [<ffffffff812e3c75>] mutex_lock_nested+0x2a/0x31
 [<ffffffffa0041155>] hci_conn_timeout+0x62/0x158 [bluetooth]
 [<ffffffff810357af>] process_one_work+0x178/0x2bf
 [<ffffffff81035751>] ? process_one_work+0x11a/0x2bf
 [<ffffffff81055af3>] ? lock_acquired+0x1d0/0x1df
 [<ffffffffa00410f3>] ? hci_acl_disconn+0x65/0x65 [bluetooth]
 [<ffffffff81036178>] worker_thread+0xce/0x152
 [<ffffffff810407ed>] ? finish_task_switch+0x45/0xc5
 [<ffffffff810360aa>] ? manage_workers.isra.25+0x16a/0x16a
 [<ffffffff81039a03>] kthread+0x95/0x9d
 [<ffffffff812e7754>] kernel_thread_helper+0x4/0x10
 [<ffffffff812e5db4>] ? retint_restore_args+0x13/0x13
 [<ffffffff8103996e>] ? __init_kthread_worker+0x55/0x55
 [<ffffffff812e7750>] ? gs_change+0x13/0x13

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@openbossa.org>
Reviewed-by: Ulisses Furquim <ulisses@profusion.mobi>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
2012-02-15 13:09:26 +02:00
..
9p 9p: Reduce object size with CONFIG_NET_9P_DEBUG 2012-01-05 10:51:44 -06:00
bluetooth Bluetooth: Fix potential deadlock 2012-02-15 13:09:26 +02:00
caif caif-spi: Bugfix for dump upon device removal 2011-12-06 13:34:12 -05:00
irda
iucv af_iucv: get rid of state IUCV_SEVERED 2011-12-20 14:05:03 -05:00
netfilter Merge branch 'nf-next' of git://1984.lsi.us.es/net-next 2011-12-25 02:21:45 -05:00
netns netns: Fail conspicously if someone uses net_generic at an inappropriate time. 2012-01-27 21:06:02 -05:00
nfc NFC: Export a new attribute nfcid1 in target info 2012-01-04 14:30:43 -05:00
phonet net: dont hold rtnl mutex during netlink dump callbacks 2011-05-02 15:26:28 -07:00
sctp Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2011-12-23 17:13:56 -05:00
tc_act
act_api.h net: sched: constify tcf_proto and tc_action 2011-07-06 02:52:16 -07:00
addrconf.h ipv6: Check RA for sllao when configuring optimistic ipv6 address (v2) 2012-01-04 15:53:20 -05:00
af_ieee802154.h
af_rxrpc.h net: Remove __KERNEL__ cpp checks from include/net 2011-04-24 10:54:56 -07:00
af_unix.h af_unix: Move CINQ/COUTQ code to helpers 2011-12-30 16:45:45 -05:00
ah.h
arp.h ipv6: Use universal hash for NDISC. 2011-12-28 15:06:58 -05:00
atmclip.h atm: clip: Use device neigh support on top of "arp_tbl". 2011-11-30 18:51:03 -05:00
ax25.h atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
ax88796.h
cfg80211-wext.h cfg80211: remove unused wext handler exports 2011-08-08 14:26:29 -04:00
cfg80211.h kernel-doc: fix new warnings in cfg80211.h 2012-01-23 08:44:54 -08:00
checksum.h
cipso_ipv4.h doc: Update the email address for Paul Moore in various source files 2011-08-01 17:58:33 -07:00
cls_cgroup.h
compat.h net: Add sendmmsg socket system call 2011-05-05 11:10:14 -07:00
datalink.h
dcbevent.h dcb: Add stub routines for !CONFIG_DCB 2011-10-06 15:49:51 -04:00
dcbnl.h dcb: add DCBX mode to event notifier attributes 2011-10-06 15:49:51 -04:00
dn_dev.h
dn_fib.h
dn_neigh.h
dn_nsp.h
dn_route.h
dn.h
dsa.h dsa: Include linux/if_ether.h to fix build error 2011-12-01 11:41:06 -05:00
dsfield.h
dst_ops.h net: Rename the dst_opt default_mtu method to mtu 2011-11-26 14:29:50 -05:00
dst.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2011-12-23 17:13:56 -05:00
esp.h
ethoc.h
fib_rules.h
flow_keys.h flow_dissector: use a 64bit load/store 2011-11-29 13:17:03 -05:00
flow.h net: fix some sparse errors 2012-01-17 10:31:12 -05:00
garp.h garp: remove last synchronize_rcu() call 2011-05-12 17:46:56 -04:00
gen_stats.h
genetlink.h genetlink: Add genl_notify() 2011-12-03 09:35:05 -08:00
gre.h
icmp.h ipv4: reduce percpu needs for icmpmsg mibs 2011-11-09 16:04:20 -05:00
ieee80211_radiotap.h wireless: move ieee80211chan2mhz macro 2011-11-11 12:32:50 -05:00
ieee802154_netdev.h
ieee802154.h 6LoWPAN: add fragmentation support 2011-11-14 00:19:42 -05:00
if_inet6.h ipv6: updates to privacy addresses per RFC 4941. 2011-08-01 18:05:00 -07:00
inet6_connection_sock.h inet: Pass flowi to ->queue_xmit(). 2011-05-08 15:28:28 -07:00
inet6_hashtables.h net: use IS_ENABLED(CONFIG_IPV6) 2011-12-11 18:25:16 -05:00
inet_common.h
inet_connection_sock.h net: rename sk_clone to sk_clone_lock 2011-11-08 17:07:07 -05:00
inet_ecn.h inet: add rfc 3168 extract in front of INET_ECN_encapsulate() 2011-10-22 01:25:23 -04:00
inet_frag.h
inet_hashtables.h atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
inet_sock.h net: use IS_ENABLED(CONFIG_IPV6) 2011-12-11 18:25:16 -05:00
inet_timewait_sock.h inet: remove rcu protection on tw_net 2011-12-14 13:34:55 -05:00
inetpeer.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2011-12-02 13:49:21 -05:00
ip6_checksum.h
ip6_fib.h IPv6: Avoid taking write lock for /proc/net/ipv6_route 2011-12-30 17:07:33 -05:00
ip6_route.h Merge branch 'nf-next' of git://1984.lsi.us.es/net-next 2011-12-25 02:21:45 -05:00
ip6_tunnel.h
ip_fib.h ipv4: Call fib_select_default() only when actually necessary. 2011-04-14 15:05:22 -07:00
ip_vs.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-01-02 18:56:49 -05:00
ip.h net: use IS_ENABLED(CONFIG_IPV6) 2011-12-11 18:25:16 -05:00
ipcomp.h
ipconfig.h
ipip.h
ipv6.h ipv6: Add fragment reporting to ipv6_skip_exthdr(). 2011-12-03 09:35:10 -08:00
ipx.h net: Remove __KERNEL__ cpp checks from include/net 2011-04-24 10:54:56 -07:00
iw_handler.h
lapb.h wan: make LAPB callbacks const 2011-09-16 19:20:20 -04:00
lib80211.h include: replace linux/module.h with "struct module" wherever possible 2011-10-31 19:32:32 -04:00
llc_c_ac.h
llc_c_ev.h
llc_c_st.h
llc_conn.h
llc_if.h
llc_pdu.h bonding,llc: Fix structure sizeof incompatibility for some PDUs 2011-05-13 15:13:24 -04:00
llc_s_ac.h
llc_s_ev.h
llc_s_st.h
llc_sap.h
llc.h atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
mac80211.h Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-01-08 13:21:22 -08:00
mip6.h
mld.h
ndisc.h ipv6: Create fast inline ipv6 neigh lookup just like ipv4. 2011-12-28 15:41:23 -05:00
neighbour.h ipv6: Use universal hash for NDISC. 2011-12-28 15:06:58 -05:00
net_namespace.h net: use IS_ENABLED(CONFIG_IPV6) 2011-12-11 18:25:16 -05:00
net_ratelimit.h net: Kill ratelimit.h dependency in linux/net.h 2011-05-27 13:41:33 -04:00
netdma.h
netevent.h net: Remove __KERNEL__ cpp checks from include/net 2011-04-24 10:54:56 -07:00
netlabel.h doc: Update the email address for Paul Moore in various source files 2011-08-01 17:58:33 -07:00
netlink.h netlink: clarify attribute length check documentation 2011-11-04 17:48:23 -04:00
netprio_cgroup.h netprio_cgroup.h: dont include module.h from other includes 2012-01-24 16:42:26 -05:00
netrom.h
nexthop.h
nl802154.h
p8022.h
ping.h net: ping: fix build failure 2011-05-17 14:16:58 -04:00
pkt_cls.h
pkt_sched.h net: sched: constify tcf_proto and tc_action 2011-07-06 02:52:16 -07:00
protocol.h net: use IS_ENABLED(CONFIG_IPV6) 2011-12-11 18:25:16 -05:00
psnap.h
raw.h
rawv6.h net: Remove __KERNEL__ cpp checks from include/net 2011-04-24 10:54:56 -07:00
red.h net_sched: sfq: add optional RED on top of SFQ 2012-01-12 20:05:28 -08:00
regulatory.h cfg80211: pass DFS region to drivers through reg_notifier() 2011-11-21 16:20:41 -05:00
request_sock.h tcp: Change possible SYN flooding messages 2011-09-15 14:49:43 -04:00
rose.h
route.h route: struct rtable can be const in rt_is_input_route and rt_is_output_route 2011-11-26 14:29:51 -05:00
rtnetlink.h rtnetlink: Compute and store minimum ifinfo dump size 2011-06-09 20:38:07 -07:00
sch_generic.h net: sch_generic remove redundant use of <linux/module.h> 2011-10-31 19:32:25 -04:00
scm.h af_unix: dont send SCM_CREDENTIALS by default 2011-09-28 13:29:50 -04:00
secure_seq.h tcp: add const qualifiers where possible 2011-10-21 05:22:42 -04:00
slhc_vj.h
snmp.h Merge branch 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2012-01-09 13:08:28 -08:00
sock.h net: explicitly add jump_label.h header to sock.h 2012-01-26 17:13:26 -05:00
stp.h
tcp_memcontrol.h tcp buffer limitation: per-cgroup limit 2011-12-12 19:04:11 -05:00
tcp_states.h
tcp.h net/tcp: Fix tcp memory limits initialization when !CONFIG_SYSCTL 2012-01-30 12:41:06 -05:00
timewait_sock.h
transp_v6.h net: relax PKTINFO non local ipv6 udp xmit check 2011-08-30 17:39:01 -04:00
udp.h net: use IS_ENABLED(CONFIG_IPV6) 2011-12-11 18:25:16 -05:00
udplite.h udplite: fast-path computation of checksum coverage 2011-10-17 19:07:30 -04:00
wext.h
wimax.h net: wimax: Remove of unused 'rfkill_input' pointer 2011-06-24 17:50:44 -07:00
wpan-phy.h
x25.h
x25device.h
xfrm.h net: remove ipv6_addr_copy() 2011-11-22 16:43:32 -05:00