scsi: lpfc: Fix rediscovery of tape device after LIP

On link up and node discovery, a remote port is registered with the SCSI
transport and the driver sets fc4_xpt_flags to track transport
registration.

A link down event causes the driver to deregister with the SCSI transport,
starting the devloss timer, and calls a local unreg routine to clear the
login state. Part of the login state is the fc4_xpt_flags.  However, with
tape devices that support sequence level error recovery, which wants to
preserve the login, the local unreg routine is skipped, thus the flags
aren't cleared.

A subsequent link up, ADISC is performed and the lpfc_nlp_reg_node()
routine is called. As the fc4_xpt_flags is not clear, it's believed the
node is already registered with the transport. Unfortunately, the
registration was already terminated. Eventually the devloss tmo timer
expires and tears down the device.

Fix by ensuring the tape device, known by the ADISC flag, is always
unregistered if the link drops.

Link: https://lore.kernel.org/r/20210910233159.115896-6-jsmart2021@gmail.comCo-developed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc_hbadisc.c

@@ -4693,8 +4693,11 @@ lpfc_nlp_state_cleanup(struct lpfc_vport *vport, struct lpfc_nodelist *ndlp,
 	/* Reg/Unreg for FCP and NVME Transport interface */
 	if ((old_state == NLP_STE_MAPPED_NODE ||
 	     old_state == NLP_STE_UNMAPPED_NODE)) {
-		/* For nodes marked for ADISC, Handle unreg in ADISC cmpl */
-		if (!(ndlp->nlp_flag & NLP_NPR_ADISC))
+		/* For nodes marked for ADISC, Handle unreg in ADISC cmpl
+		 * if linkup. In linkdown do unreg_node
+		 */
+		if (!(ndlp->nlp_flag & NLP_NPR_ADISC) ||
+		    !lpfc_is_link_up(vport->phba))
 			lpfc_nlp_unreg_node(vport, ndlp);
 	}