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405280887f
This patch reduces the critical section protected by sco_conn_lock in sco_conn_ready function. The lock is acquired only when it is really needed. This patch fixes the following lockdep warning which is generated when the host terminates a SCO connection. Today, this warning is a false positive. There is no way those two threads reported by lockdep are running at the same time since hdev->workqueue (where rx_work is queued) is single-thread. However, if somehow this behavior is changed in future, we will have a potential deadlock. ====================================================== [ INFO: possible circular locking dependency detected ] 3.8.0-rc1+ #7 Not tainted ------------------------------------------------------- kworker/u:1H/1018 is trying to acquire lock: (&(&conn->lock)->rlock){+.+...}, at: [<ffffffffa0033ba6>] sco_chan_del+0x66/0x190 [bluetooth] but task is already holding lock: (slock-AF_BLUETOOTH-BTPROTO_SCO){+.+...}, at: [<ffffffffa0033d5a>] sco_conn_del+0x8a/0xe0 [bluetooth] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (slock-AF_BLUETOOTH-BTPROTO_SCO){+.+...}: [<ffffffff81083011>] lock_acquire+0xb1/0xe0 [<ffffffff813efd01>] _raw_spin_lock+0x41/0x80 [<ffffffffa003436e>] sco_connect_cfm+0xbe/0x350 [bluetooth] [<ffffffffa0015d6c>] hci_event_packet+0xd3c/0x29b0 [bluetooth] [<ffffffffa0004583>] hci_rx_work+0x133/0x870 [bluetooth] [<ffffffff8104d65f>] process_one_work+0x2bf/0x4f0 [<ffffffff81050022>] worker_thread+0x2b2/0x3e0 [<ffffffff81056021>] kthread+0xd1/0xe0 [<ffffffff813f14bc>] ret_from_fork+0x7c/0xb0 -> #0 (&(&conn->lock)->rlock){+.+...}: [<ffffffff81082215>] __lock_acquire+0x1465/0x1c70 [<ffffffff81083011>] lock_acquire+0xb1/0xe0 [<ffffffff813efd01>] _raw_spin_lock+0x41/0x80 [<ffffffffa0033ba6>] sco_chan_del+0x66/0x190 [bluetooth] [<ffffffffa0033d6d>] sco_conn_del+0x9d/0xe0 [bluetooth] [<ffffffffa0034653>] sco_disconn_cfm+0x53/0x60 [bluetooth] [<ffffffffa000fef3>] hci_disconn_complete_evt.isra.54+0x363/0x3c0 [bluetooth] [<ffffffffa00150f7>] hci_event_packet+0xc7/0x29b0 [bluetooth] [<ffffffffa0004583>] hci_rx_work+0x133/0x870 [bluetooth] [<ffffffff8104d65f>] process_one_work+0x2bf/0x4f0 [<ffffffff81050022>] worker_thread+0x2b2/0x3e0 [<ffffffff81056021>] kthread+0xd1/0xe0 [<ffffffff813f14bc>] ret_from_fork+0x7c/0xb0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(slock-AF_BLUETOOTH-BTPROTO_SCO); lock(&(&conn->lock)->rlock); lock(slock-AF_BLUETOOTH-BTPROTO_SCO); lock(&(&conn->lock)->rlock); *** DEADLOCK *** 4 locks held by kworker/u:1H/1018: #0: (hdev->name#2){.+.+.+}, at: [<ffffffff8104d5f8>] process_one_work+0x258/0x4f0 #1: ((&hdev->rx_work)){+.+.+.}, at: [<ffffffff8104d5f8>] process_one_work+0x258/0x4f0 #2: (&hdev->lock){+.+.+.}, at: [<ffffffffa000fbe9>] hci_disconn_complete_evt.isra.54+0x59/0x3c0 [bluetooth] #3: (slock-AF_BLUETOOTH-BTPROTO_SCO){+.+...}, at: [<ffffffffa0033d5a>] sco_conn_del+0x8a/0xe0 [bluetooth] stack backtrace: Pid: 1018, comm: kworker/u:1H Not tainted 3.8.0-rc1+ #7 Call Trace: [<ffffffff813e92f9>] print_circular_bug+0x1fb/0x20c [<ffffffff81082215>] __lock_acquire+0x1465/0x1c70 [<ffffffff81083011>] lock_acquire+0xb1/0xe0 [<ffffffffa0033ba6>] ? sco_chan_del+0x66/0x190 [bluetooth] [<ffffffff813efd01>] _raw_spin_lock+0x41/0x80 [<ffffffffa0033ba6>] ? sco_chan_del+0x66/0x190 [bluetooth] [<ffffffffa0033ba6>] sco_chan_del+0x66/0x190 [bluetooth] [<ffffffffa0033d6d>] sco_conn_del+0x9d/0xe0 [bluetooth] [<ffffffffa0034653>] sco_disconn_cfm+0x53/0x60 [bluetooth] [<ffffffffa000fef3>] hci_disconn_complete_evt.isra.54+0x363/0x3c0 [bluetooth] [<ffffffffa000fbd0>] ? hci_disconn_complete_evt.isra.54+0x40/0x3c0 [bluetooth] [<ffffffffa00150f7>] hci_event_packet+0xc7/0x29b0 [bluetooth] [<ffffffff81202e90>] ? __dynamic_pr_debug+0x80/0x90 [<ffffffff8133ff7d>] ? kfree_skb+0x2d/0x40 [<ffffffffa0021644>] ? hci_send_to_monitor+0x1a4/0x1c0 [bluetooth] [<ffffffffa0004583>] hci_rx_work+0x133/0x870 [bluetooth] [<ffffffff8104d5f8>] ? process_one_work+0x258/0x4f0 [<ffffffff8104d65f>] process_one_work+0x2bf/0x4f0 [<ffffffff8104d5f8>] ? process_one_work+0x258/0x4f0 [<ffffffff8104fdc1>] ? worker_thread+0x51/0x3e0 [<ffffffffa0004450>] ? hci_tx_work+0x800/0x800 [bluetooth] [<ffffffff81050022>] worker_thread+0x2b2/0x3e0 [<ffffffff8104fd70>] ? busy_worker_rebind_fn+0x100/0x100 [<ffffffff81056021>] kthread+0xd1/0xe0 [<ffffffff81055f50>] ? flush_kthread_worker+0xc0/0xc0 [<ffffffff813f14bc>] ret_from_fork+0x7c/0xb0 [<ffffffff81055f50>] ? flush_kthread_worker+0xc0/0xc0 Signed-off-by: Andre Guedes <andre.guedes@openbossa.org> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk> |
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| 9p | ||
| 802 | ||
| 8021q | ||
| appletalk | ||
| atm | ||
| ax25 | ||
| batman-adv | ||
| bluetooth | ||
| bridge | ||
| caif | ||
| can | ||
| ceph | ||
| core | ||
| dcb | ||
| dccp | ||
| decnet | ||
| dns_resolver | ||
| dsa | ||
| ethernet | ||
| ieee802154 | ||
| ipv4 | ||
| ipv6 | ||
| ipx | ||
| irda | ||
| iucv | ||
| key | ||
| l2tp | ||
| lapb | ||
| llc | ||
| mac80211 | ||
| mac802154 | ||
| netfilter | ||
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| nfc | ||
| openvswitch | ||
| packet | ||
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| rds | ||
| rfkill | ||
| rose | ||
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| sched | ||
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| sunrpc | ||
| tipc | ||
| unix | ||
| wanrouter | ||
| wimax | ||
| wireless | ||
| x25 | ||
| xfrm | ||
| compat.c | ||
| Kconfig | ||
| Makefile | ||
| nonet.c | ||
| socket.c | ||
| sysctl_net.c | ||