[SCSI] libfc: in fc_lport_destroy, flush rports after turning off link

During an fcoe module unload, we saw a problem where fc_rport_work()
finds the lport has been freed.  The rdata points to an area
containing 0x6b6b6b6b... the pool poison value from kmem_free().

In fcoe_if_destroy() we call fc_fabric_logoff() then fc_lport_destroy().
fc_fabric_logoff() flushes the remote port work, but we're still receiving
requests, and an RSCN or PLOGI arrives which creates more rports.

Note that although the LLD also checks link_up, it doesn't do it
under the lport mutex, so it can deliver frames to
fc_lport_recv_req() even after link_up is cleared.
So, re-check link_up there.

We need to flush the rports by calling disc_stop_final()
after we clear link_up.

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@HansenPartnership.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/libfc/fc_lport.c

@@ -643,6 +643,7 @@ int fc_lport_destroy(struct fc_lport *lport)
 	mutex_unlock(&lport->lp_mutex);
 
 	lport->tt.fcp_abort_io(lport);
+	lport->tt.disc_stop_final(lport);
 	lport->tt.exch_mgr_reset(lport, 0, 0);
 	return 0;
 }
@@ -844,7 +845,10 @@ static void fc_lport_recv_req(struct fc_lport *lport, struct fc_seq *sp,
 	 * RSCN here.  These don't require a session.
 	 * Even if we had a session, it might not be ready.
 	 */
-	if (fh->fh_type == FC_TYPE_ELS && fh->fh_r_ctl == FC_RCTL_ELS_REQ) {
+	if (!lport->link_up)
+		fc_frame_free(fp);
+	else if (fh->fh_type == FC_TYPE_ELS &&
+		 fh->fh_r_ctl == FC_RCTL_ELS_REQ) {
 		/*
 		 * Check opcode.
 		 */