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/openbmc/linux/net/bluetooth/
H A Diso.c241f5193 Tue Dec 06 18:34:42 CST 2022 Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Bluetooth: ISO: Avoid circular locking dependency

This attempts to avoid circular locking dependency between sock_lock
and hdev_lock:

WARNING: possible circular locking dependency detected
6.0.0-rc7-03728-g18dd8ab0a783 #3 Not tainted
------------------------------------------------------
kworker/u3:2/53 is trying to acquire lock:
ffff888000254130 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0}, at:
iso_conn_del+0xbd/0x1d0
but task is already holding lock:
ffffffff9f39a080 (hci_cb_list_lock){+.+.}-{3:3}, at:
hci_le_cis_estabilished_evt+0x1b5/0x500
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+0x10e/0xfe0
hci_le_remote_feat_complete_evt+0x17f/0x320
hci_event_packet+0x39c/0x7d0
hci_rx_work+0x2bf/0x950
process_one_work+0x569/0x980
worker_thread+0x2a3/0x6f0
kthread+0x153/0x180
ret_from_fork+0x22/0x30
-> #1 (&hdev->lock){+.+.}-{3:3}:
__mutex_lock+0x10e/0xfe0
iso_connect_cis+0x6f/0x5a0
iso_sock_connect+0x1af/0x710
__sys_connect+0x17e/0x1b0
__x64_sys_connect+0x37/0x50
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x62/0xcc
-> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0}:
__lock_acquire+0x1b51/0x33d0
lock_acquire+0x16f/0x3b0
lock_sock_nested+0x32/0x80
iso_conn_del+0xbd/0x1d0
iso_connect_cfm+0x226/0x680
hci_le_cis_estabilished_evt+0x1ed/0x500
hci_event_packet+0x39c/0x7d0
hci_rx_work+0x2bf/0x950
process_one_work+0x569/0x980
worker_thread+0x2a3/0x6f0
kthread+0x153/0x180
ret_from_fork+0x22/0x30
other info that might help us debug this:
Chain exists of:
sk_lock-AF_BLUETOOTH-BTPROTO_ISO --> &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_ISO);
*** DEADLOCK ***
4 locks held by kworker/u3:2/53:
#0: ffff8880021d9130 ((wq_completion)hci0#2){+.+.}-{0:0}, at:
process_one_work+0x4ad/0x980
#1: ffff888002387de0 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0},
at: process_one_work+0x4ad/0x980
#2: ffff888001ac0070 (&hdev->lock){+.+.}-{3:3}, at:
hci_le_cis_estabilished_evt+0xc3/0x500
#3: ffffffff9f39a080 (hci_cb_list_lock){+.+.}-{3:3}, at:
hci_le_cis_estabilished_evt+0x1b5/0x500

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>