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a51cd2be86
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> |
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