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9a8ec9e8eb
This attempts to fix the following trace: ====================================================== WARNING: possible circular locking dependency detected 6.3.0-rc2-g0b93eeba4454 #4703 Not tainted ------------------------------------------------------ kworker/u3:0/46 is trying to acquire lock: ffff888001fd9130 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_connect_cfm+0x118/0x4a0 but task is already holding lock: ffffffff831e3340 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_sync_conn_complete_evt+0x1ad/0x3d0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (hci_cb_list_lock){+.+.}-{3:3}: __mutex_lock+0x13b/0xcc0 hci_sync_conn_complete_evt+0x1ad/0x3d0 hci_event_packet+0x55c/0x7c0 hci_rx_work+0x34c/0xa00 process_one_work+0x575/0x910 worker_thread+0x89/0x6f0 kthread+0x14e/0x180 ret_from_fork+0x2b/0x50 -> #1 (&hdev->lock){+.+.}-{3:3}: __mutex_lock+0x13b/0xcc0 sco_sock_connect+0xfc/0x630 __sys_connect+0x197/0x1b0 __x64_sys_connect+0x37/0x50 do_syscall_64+0x42/0x90 entry_SYSCALL_64_after_hwframe+0x70/0xda -> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}: __lock_acquire+0x18cc/0x3740 lock_acquire+0x151/0x3a0 lock_sock_nested+0x32/0x80 sco_connect_cfm+0x118/0x4a0 hci_sync_conn_complete_evt+0x1e6/0x3d0 hci_event_packet+0x55c/0x7c0 hci_rx_work+0x34c/0xa00 process_one_work+0x575/0x910 worker_thread+0x89/0x6f0 kthread+0x14e/0x180 ret_from_fork+0x2b/0x50 other info that might help us debug this: Chain exists of: sk_lock-AF_BLUETOOTH-BTPROTO_SCO --> &hdev->lock --> hci_cb_list_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(hci_cb_list_lock); lock(&hdev->lock); lock(hci_cb_list_lock); lock(sk_lock-AF_BLUETOOTH-BTPROTO_SCO); *** DEADLOCK *** 4 locks held by kworker/u3:0/46: #0: ffff8880028d1130 ((wq_completion)hci0#2){+.+.}-{0:0}, at: process_one_work+0x4c0/0x910 #1: ffff8880013dfde0 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x4c0/0x910 #2: ffff8880025d8070 (&hdev->lock){+.+.}-{3:3}, at: hci_sync_conn_complete_evt+0xa6/0x3d0 #3: ffffffffb79e3340 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_sync_conn_complete_evt+0x1ad/0x3d0 Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.