From: Jiri Kosina jkosina@suse.cz
[ Upstream commit 17486960d79b900c45e0bb8fbcac0262848582ba ]
Commit eab2404ba798 ("Bluetooth: Add BT_PHY socket option") added a dependency between socket lock and hci_dev->lock that could lead to deadlock.
It turns out that hci_conn_get_phy() is not in any way relying on hdev being immutable during the runtime of this function, neither does it even look at any of the members of hdev, and as such there is no need to hold that lock.
This fixes the lockdep splat below:
====================================================== WARNING: possible circular locking dependency detected 5.12.0-rc1-00026-g73d464503354 #10 Not tainted ------------------------------------------------------ bluetoothd/1118 is trying to acquire lock: ffff8f078383c078 (&hdev->lock){+.+.}-{3:3}, at: hci_conn_get_phy+0x1c/0x150 [bluetooth]
but task is already holding lock: ffff8f07e831d920 (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+.}-{0:0}, at: l2cap_sock_getsockopt+0x8b/0x610
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+.}-{0:0}: lock_sock_nested+0x72/0xa0 l2cap_sock_ready_cb+0x18/0x70 [bluetooth] l2cap_config_rsp+0x27a/0x520 [bluetooth] l2cap_sig_channel+0x658/0x1330 [bluetooth] l2cap_recv_frame+0x1ba/0x310 [bluetooth] hci_rx_work+0x1cc/0x640 [bluetooth] process_one_work+0x244/0x5f0 worker_thread+0x3c/0x380 kthread+0x13e/0x160 ret_from_fork+0x22/0x30
-> #2 (&chan->lock#2/1){+.+.}-{3:3}: __mutex_lock+0xa3/0xa10 l2cap_chan_connect+0x33a/0x940 [bluetooth] l2cap_sock_connect+0x141/0x2a0 [bluetooth] __sys_connect+0x9b/0xc0 __x64_sys_connect+0x16/0x20 do_syscall_64+0x33/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #1 (&conn->chan_lock){+.+.}-{3:3}: __mutex_lock+0xa3/0xa10 l2cap_chan_connect+0x322/0x940 [bluetooth] l2cap_sock_connect+0x141/0x2a0 [bluetooth] __sys_connect+0x9b/0xc0 __x64_sys_connect+0x16/0x20 do_syscall_64+0x33/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #0 (&hdev->lock){+.+.}-{3:3}: __lock_acquire+0x147a/0x1a50 lock_acquire+0x277/0x3d0 __mutex_lock+0xa3/0xa10 hci_conn_get_phy+0x1c/0x150 [bluetooth] l2cap_sock_getsockopt+0x5a9/0x610 [bluetooth] __sys_getsockopt+0xcc/0x200 __x64_sys_getsockopt+0x20/0x30 do_syscall_64+0x33/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae
other info that might help us debug this:
Chain exists of: &hdev->lock --> &chan->lock#2/1 --> sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP); lock(&chan->lock#2/1); lock(sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP); lock(&hdev->lock);
*** DEADLOCK ***
1 lock held by bluetoothd/1118: #0: ffff8f07e831d920 (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+.}-{0:0}, at: l2cap_sock_getsockopt+0x8b/0x610 [bluetooth]
stack backtrace: CPU: 3 PID: 1118 Comm: bluetoothd Not tainted 5.12.0-rc1-00026-g73d464503354 #10 Hardware name: LENOVO 20K5S22R00/20K5S22R00, BIOS R0IET38W (1.16 ) 05/31/2017 Call Trace: dump_stack+0x7f/0xa1 check_noncircular+0x105/0x120 ? __lock_acquire+0x147a/0x1a50 __lock_acquire+0x147a/0x1a50 lock_acquire+0x277/0x3d0 ? hci_conn_get_phy+0x1c/0x150 [bluetooth] ? __lock_acquire+0x2e1/0x1a50 ? lock_is_held_type+0xb4/0x120 ? hci_conn_get_phy+0x1c/0x150 [bluetooth] __mutex_lock+0xa3/0xa10 ? hci_conn_get_phy+0x1c/0x150 [bluetooth] ? lock_acquire+0x277/0x3d0 ? mark_held_locks+0x49/0x70 ? mark_held_locks+0x49/0x70 ? hci_conn_get_phy+0x1c/0x150 [bluetooth] hci_conn_get_phy+0x1c/0x150 [bluetooth] l2cap_sock_getsockopt+0x5a9/0x610 [bluetooth] __sys_getsockopt+0xcc/0x200 __x64_sys_getsockopt+0x20/0x30 do_syscall_64+0x33/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fb73df33eee Code: 48 8b 0d 85 0f 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 37 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 52 0f 0c 00 f7 d8 64 89 01 48 RSP: 002b:00007fffcfbbbf08 EFLAGS: 00000203 ORIG_RAX: 0000000000000037 RAX: ffffffffffffffda RBX: 0000000000000019 RCX: 00007fb73df33eee RDX: 000000000000000e RSI: 0000000000000112 RDI: 0000000000000018 RBP: 0000000000000000 R08: 00007fffcfbbbf44 R09: 0000000000000000 R10: 00007fffcfbbbf3c R11: 0000000000000203 R12: 0000000000000000 R13: 0000000000000018 R14: 0000000000000000 R15: 0000556fcefc70d0
Fixes: eab2404ba798 ("Bluetooth: Add BT_PHY socket option") Signed-off-by: Jiri Kosina jkosina@suse.cz Signed-off-by: Marcel Holtmann marcel@holtmann.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/bluetooth/hci_conn.c | 4 ---- 1 file changed, 4 deletions(-)
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c index 4f1cd8063e72..6bd222443f15 100644 --- a/net/bluetooth/hci_conn.c +++ b/net/bluetooth/hci_conn.c @@ -1797,8 +1797,6 @@ u32 hci_conn_get_phy(struct hci_conn *conn) { u32 phys = 0;
- hci_dev_lock(conn->hdev); - /* BLUETOOTH CORE SPECIFICATION Version 5.2 | Vol 2, Part B page 471: * Table 6.2: Packets defined for synchronous, asynchronous, and * CSB logical transport types. @@ -1895,7 +1893,5 @@ u32 hci_conn_get_phy(struct hci_conn *conn) break; }
- hci_dev_unlock(conn->hdev); - return phys; }