On 10/30/2018 09:00 AM, Oleksij Rempel wrote:
> 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@xxxxxxxxxxxxxx>
Added to linux-can-next/j1939.
Marc
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