af_iucv: avoid path quiesce of severed path in shutdown()
af_iucv: avoid path quiesce of severed path in shutdown()

An af_iucv stress test showed -EPIPE results for sendmsg()
calls. They are caused by quiescing a path even though it has
been already severed by peer. For IUCV transport shutdown()
consists of 2 steps:
(1) sending the shutdown message to peer
(2) quiescing the iucv path
If the iucv path between these 2 steps is severed due to peer
closing the path, the quiesce step is no longer needed.

Signed-off-by: Ursula Braun <3498481c3b1fee38251ffe7b781cda34b574142e@de.ibm.com>
Signed-off-by: Frank Blaschka <36098d5dd8cbf2850e11cda8573079ed2f367115@linux.vnet.ibm.com>
Reported-by: Philipp Hachtmann <1771e156037a6c5e310b05e618871853ba8c42e9@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs