bluetooth: rfcomm_dev_state_change deadlock fix
There's logic in __rfcomm_dlc_close: rfcomm_dlc_lock(d); d->state = BT_CLOSED; d->state_changed(d, err); rfcomm_dlc_unlock(d); In rfcomm_dev_state_change, it's possible that rfcomm_dev_put try to take the dlc lock, then we will deadlock. Here fixed it by unlock dlc before rfcomm_dev_get in rfcomm_dev_state_change. why not unlock just before rfcomm_dev_put? it's because there's another problem. rfcomm_dev_get/rfcomm_dev_del will take rfcomm_dev_lock, but in rfcomm_dev_add the lock order is : rfcomm_dev_lock --> dlc lock so I unlock dlc before the taken of rfcomm_dev_lock. Actually it's a regression caused by commit 1905f6c7 ("bluetooth : __rfcomm_dlc_close lock fix"), the dlc state_change could be two callbacks : rfcomm_sk_state_change and rfcomm_dev_state_change. I missed the rfcomm_sk_state_change that time. Thanks Arjan van de Ven <arjan@linux.intel.com> for the effort in commit 4c8411f8 ("bluetooth: fix locking bug in the rfcomm socket cleanup handling") but he missed the rfcomm_dev_state_change lock issue. Signed-off-by: NDave Young <hidave.darkstar@gmail.com> Acked-by: NMarcel Holtmann <marcel@holtmann.org> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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