A deadlock might occur if name table is withdrawn in socket release
routine, and while packets are still being received from bearer.
CPU0 CPU1
T0: recv_msg() release()
T1: tipc_recv_msg() tipc_withdraw()
T2: [grab node lock] [grab port lock]
T3: tipc_link_wakeup_ports() tipc_nametbl_withdraw()
T4: [grab port lock]* named_cluster_distribute()
T5: wakeupdispatch() tipc_link_send()
T6: [grab node lock]*
The opposite order of holding port lock and node lock on above two
different paths may result in a deadlock. If socket lock instead of
port lock is used to protect port instance in tipc_withdraw(), the
reverse order of holding port lock and node lock will be eliminated,
as a result, the deadlock is killed as well.
Reported-by: Lars Everbrand <lars.everbrand@ericsson.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
84602761ca