* Lockdep report for hci_conn_get_phy()
@ 2021-03-04 13:08 Jiri Kosina
2021-03-16 10:28 ` Jiri Kosina
0 siblings, 1 reply; 5+ messages in thread
From: Jiri Kosina @ 2021-03-04 13:08 UTC (permalink / raw)
To: Marcel Holtmann, Johan Hedberg, Luiz Augusto von Dentz
Cc: linux-bluetooth, linux-kernel
Hi,
I am getting the lockdep splat below with current Linus' tree (5.12-rc1).
I haven't yet analyzed the dependency chain and the code, but sending out
early in case someone has seen this before and analyzed / fixed it
already.
Thanks.
======================================================
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
--
Jiri Kosina
SUSE Labs
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: Lockdep report for hci_conn_get_phy()
2021-03-04 13:08 Lockdep report for hci_conn_get_phy() Jiri Kosina
@ 2021-03-16 10:28 ` Jiri Kosina
2021-03-16 14:08 ` [PATCH] Bluetooth: avoid deadlock between hci_dev->lock and socket lock Jiri Kosina
0 siblings, 1 reply; 5+ messages in thread
From: Jiri Kosina @ 2021-03-16 10:28 UTC (permalink / raw)
To: Marcel Holtmann, Johan Hedberg, Luiz Augusto von Dentz
Cc: linux-bluetooth, linux-kernel
On Thu, 4 Mar 2021, Jiri Kosina wrote:
> ======================================================
> 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
So looking at the code and digging a bit in the history, it seems like the
above dependency chain has been there since ever ...
> 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
... but the sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP -> conn->hdev dependency
has been added only in eab2404ba798 ("Bluetooth: Add BT_PHY socket
option") and I've started to see this splat only now as I've probably
recently acquired userspace that excercises this getsockopt(BT_PHY).
--
Jiri Kosina
SUSE Labs
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH] Bluetooth: avoid deadlock between hci_dev->lock and socket lock
2021-03-16 10:28 ` Jiri Kosina
@ 2021-03-16 14:08 ` Jiri Kosina
2021-03-16 14:30 ` Marcel Holtmann
0 siblings, 1 reply; 5+ messages in thread
From: Jiri Kosina @ 2021-03-16 14:08 UTC (permalink / raw)
To: Marcel Holtmann, Johan Hedberg, Luiz Augusto von Dentz
Cc: linux-bluetooth, linux-kernel
From: Jiri Kosina <jkosina@suse.cz>
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>
---
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 6ffa89e3ba0a..f72646690539 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1830,8 +1830,6 @@ 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.
@@ -1928,7 +1926,5 @@ u32 hci_conn_get_phy(struct hci_conn *conn)
break;
}
- hci_dev_unlock(conn->hdev);
-
return phys;
}
--
Jiri Kosina
SUSE Labs
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] Bluetooth: avoid deadlock between hci_dev->lock and socket lock
2021-03-16 14:08 ` [PATCH] Bluetooth: avoid deadlock between hci_dev->lock and socket lock Jiri Kosina
@ 2021-03-16 14:30 ` Marcel Holtmann
2021-03-16 14:31 ` Jiri Kosina
0 siblings, 1 reply; 5+ messages in thread
From: Marcel Holtmann @ 2021-03-16 14:30 UTC (permalink / raw)
To: Jiri Kosina
Cc: Johan Hedberg, Luiz Augusto von Dentz, linux-bluetooth, linux-kernel
Hi Jiri,
> 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>
> ---
> net/bluetooth/hci_conn.c | 4 ----
> 1 file changed, 4 deletions(-)
patch has been applied to bluetooth-next tree.
Regards
Marcel
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] Bluetooth: avoid deadlock between hci_dev->lock and socket lock
2021-03-16 14:30 ` Marcel Holtmann
@ 2021-03-16 14:31 ` Jiri Kosina
0 siblings, 0 replies; 5+ messages in thread
From: Jiri Kosina @ 2021-03-16 14:31 UTC (permalink / raw)
To: Marcel Holtmann
Cc: Johan Hedberg, Luiz Augusto von Dentz, linux-bluetooth, linux-kernel
On Tue, 16 Mar 2021, Marcel Holtmann wrote:
> > Fixes: eab2404ba798 ("Bluetooth: Add BT_PHY socket option")
> > Signed-off-by: Jiri Kosina <jkosina@suse.cz>
> > ---
> > net/bluetooth/hci_conn.c | 4 ----
> > 1 file changed, 4 deletions(-)
>
> patch has been applied to bluetooth-next tree.
Thanks; could it be pushed for 5.12-rc still though? It fixes an actual
possibility of deadlock.
--
Jiri Kosina
SUSE Labs
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-03-16 14:32 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-03-04 13:08 Lockdep report for hci_conn_get_phy() Jiri Kosina
2021-03-16 10:28 ` Jiri Kosina
2021-03-16 14:08 ` [PATCH] Bluetooth: avoid deadlock between hci_dev->lock and socket lock Jiri Kosina
2021-03-16 14:30 ` Marcel Holtmann
2021-03-16 14:31 ` Jiri Kosina
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