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.
Luiz Augusto von Dentz
authored
This attempts to fix the following trace: ====================================================== WARNING: possible circular locking dependency detected 6.3.0-rc2-g68fcb3a7bf97 #4706 Not tainted ------------------------------------------------------ sco-tester/31 is trying to acquire lock: ffff8880025b8070 (&hdev->lock){+.+.}-{3:3}, at: sco_sock_getsockopt+0x1fc/0xa90 but task is already holding lock: ffff888001eeb130 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_sock_getsockopt+0x104/0xa90 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}: 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 -> #1 (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 -> #0 (&hdev->lock){+.+.}-{3:3}: __lock_acquire+0x18cc/0x3740 lock_acquire+0x151/0x3a0 __mutex_lock+0x13b/0xcc0 sco_sock_getsockopt+0x1fc/0xa90 __sys_getsockopt+0xe9/0x190 __x64_sys_getsockopt+0x5b/0x70 do_syscall_64+0x42/0x90 entry_SYSCALL_64_after_hwframe+0x70/0xda other info that might help us debug this: Chain exists of: &hdev->lock --> hci_cb_list_lock --> sk_lock-AF_BLUETOOTH-BTPROTO_SCO Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sk_lock-AF_BLUETOOTH-BTPROTO_SCO); lock(hci_cb_list_lock); lock(sk_lock-AF_BLUETOOTH-BTPROTO_SCO); lock(&hdev->lock); *** DEADLOCK *** 1 lock held by sco-tester/31: #0: ffff888001eeb130 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_sock_getsockopt+0x104/0xa90 Fixes: 248733e8 ("Bluetooth: Allow querying of supported offload codecs over SCO socket") Signed-off-by:Luiz Augusto von Dentz <luiz.von.dentz@intel.com>