Hi Marcel, On 30/7/21 3:53 am, Marcel Holtmann wrote:
Hi Desmond,Commit fad003b6c8e3d ("Bluetooth: Fix inconsistent lock state with RFCOMM") fixed a lockdep warning due to sk->sk_lock.slock being acquired without disabling softirq while the lock is also used in softirq context. This was done by disabling interrupts before calling bh_lock_sock in rfcomm_sk_state_change. Later, this was changed in commit e6da0edc24ee ("Bluetooth: Acquire sk_lock.slock without disabling interrupts") to disable softirqs only. However, there is another instance of sk->sk_lock.slock being acquired without disabling softirq in rfcomm_connect_ind. This patch fixes this by disabling local bh before the call to bh_lock_sock.back in the days, the packet processing was done in a tasklet, but these days it is done in a workqueue. So shouldn’t this be just converted into a lock_sock(). Am I missing something?
Thanks for the info. I think you're right, I just didn't understand very much when I wrote this patch.
If I'm understanding correctly, it seems that both the bh_lock_sock in rfcomm_connect_ind, and spin_lock_bh in rfcomm_sk_state_change need to be changed to lock_sock, otherwise they don't provide any synchronization with other functions in RFCOMM that use lock_sock.
If that sounds correct I can prepare the patch for that. Best wishes, Desmond
