[SCSI] libfc: fix free of fc_rport_priv with timer pending

[SCSI] libfc: fix free of fc_rport_priv with timer pending

Timer crashes were caused by freeing a struct fc_rport_priv
with a timer pending, causing the timer facility list to be
corrupted.  This was during FC uplink flap tests with a lot
of targets.

After discovery, we were doing an PLOGI on an rdata that was
in DELETE state but not yet removed from the lookup list.
This moved the rdata from DELETE state to PLOGI state.
If the PLOGI exchange allocation failed and needed to be
retried, the timer scheduling could race with the free
being done by fc_rport_work().

When fc_rport_login() is called on a rport in DELETE state,
move it to a new state RESTART.  In fc_rport_work, when
handling a LOGO, STOPPED or FAILED event, look for restart
state.  In the RESTART case, don't take the rdata off the
list and after the transport remote port is deleted and
exchanges are reset, re-login to the remote port.

Note that the new RESTART state also corrects a problem we
had when re-discovering a port that had moved to DELETE state.
In that case, a new rdata was created, but the old rdata
would do an exchange manager reset affecting the FC_ID
for both the new rdata and old rdata.  With the new state,
the new port isn't logged into until after any old exchanges
are reset.

Signed-off-by: Joe Eykholt <jeykholt@cisco.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>