[SCSI] libfc: fix oops in point-to-point mode

In point-to-point mode, if the PLOGI to the remote port times
out, it can get deleted by the remote port module.  Since there's
no reference by the local port, lport->ptp_data points to a freed
rport, and when the local port is reset and tries to logout again,
an oops occurs in mutex_lock_nested().

Hold a reference count on the point-to-point rdata.
Signed-off-by: NJoe Eykholt <jeykholt@cisco.com>
Signed-off-by: NRobert Love <robert.w.love@intel.com>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>

drivers/scsi/libfc/fc_lport.c

@@ -228,9 +228,12 @@ static void fc_lport_ptp_setup(struct fc_lport *lport,
 			       u64 remote_wwnn)
 {
 	mutex_lock(&lport->disc.disc_mutex);
-	if (lport->ptp_rdata)
+	if (lport->ptp_rdata) {
 		lport->tt.rport_logoff(lport->ptp_rdata);
+		kref_put(&lport->ptp_rdata->kref, lport->tt.rport_destroy);
+	}
 	lport->ptp_rdata = lport->tt.rport_create(lport, remote_fid);
+	kref_get(&lport->ptp_rdata->kref);
 	lport->ptp_rdata->ids.port_name = remote_wwpn;
 	lport->ptp_rdata->ids.node_name = remote_wwnn;
 	mutex_unlock(&lport->disc.disc_mutex);
@@ -947,7 +950,11 @@ static void fc_lport_reset_locked(struct fc_lport *lport)
 	if (lport->dns_rdata)
 		lport->tt.rport_logoff(lport->dns_rdata);
 
-	lport->ptp_rdata = NULL;
+	if (lport->ptp_rdata) {
+		lport->tt.rport_logoff(lport->ptp_rdata);
+		kref_put(&lport->ptp_rdata->kref, lport->tt.rport_destroy);
+		lport->ptp_rdata = NULL;
+	}
 
 	lport->tt.disc_stop(lport);