The can_rx_unregister() can be called from NAPI (soft IRQ) context, at least
by j1939 stack. This leads to potential dead lock with &net->can.rcvlists_lock
called from can_rx_register:
===============================================================================
WARNING: inconsistent lock state
4.19.0-20181029-1-g3e67f95ba0d3 #3 Not tainted
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
testj1939/224 [HC0[0]:SC1[1]:HE1:SE0] takes:
1ad0fda3 (&(&net->can.rcvlists_lock)->rlock){+.?.}, at: can_rx_unregister+0x4c/0x1ac
{SOFTIRQ-ON-W} state was registered at:
lock_acquire+0xd0/0x1f4
_raw_spin_lock+0x30/0x40
can_rx_register+0x5c/0x14c
j1939_netdev_start+0xdc/0x1f8
j1939_sk_bind+0x18c/0x1c8
__sys_bind+0x70/0xb0
sys_bind+0x10/0x14
ret_fast_syscall+0x0/0x28
0xbedc9b64
irq event stamp: 2440
hardirqs last enabled at (2440): [<c01302c0>] __local_bh_enable_ip+0xac/0x184
hardirqs last disabled at (2439): [<c0130274>] __local_bh_enable_ip+0x60/0x184
softirqs last enabled at (2412): [<c08b0bf4>] release_sock+0x84/0xa4
softirqs last disabled at (2415): [<c013055c>] irq_exit+0x100/0x1b0
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&(&net->can.rcvlists_lock)->rlock);
<Interrupt>
lock(&(&net->can.rcvlists_lock)->rlock);
*** DEADLOCK ***
2 locks held by testj1939/224:
#0: 168eb13b (rcu_read_lock){....}, at: netif_receive_skb_internal+0x3c/0x350
#1: 168eb13b (rcu_read_lock){....}, at: can_receive+0x88/0x1c0
===============================================================================
To avoid this situation, we should use spin_lock_bh() instead of spin_lock().
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
24efc6d36d