scsi: lpfc: Don't remove ndlp on PRLI errors in P2P mode

In pt-2-pt mode, the initiator does not log into the target after a PRLI
error.  In pt-2-pt mode, the target responded to the PRLI by sending a
LOGO. The LOGO causes all ELS and I/Os to be aborted. This caused the PRLI
to fail. The PRLI completion path caused the discovery node to be dropped
to avoid being stick in an UNUSED (not logged in) state. As the node was
dropped there is no retry of the login and as it is pt-2-pt, there is no
RSCN to retrigger discovery. Thus the other end is not seen by the OS.

Fix by ensuring the discovery node is not dropped if connecting pt-2-pt.
This will cause PLOGI to be retried.

Link: https://lore.kernel.org/r/20210910233159.115896-7-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_els.c

@@ -2329,6 +2329,13 @@ lpfc_cmpl_els_prli(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 			lpfc_disc_state_machine(vport, ndlp, cmdiocb,
 						NLP_EVT_CMPL_PRLI);
 
+		/*
+		 * For P2P topology, retain the node so that PLOGI can be
+		 * attempted on it again.
+		 */
+		if (vport->fc_flag & FC_PT2PT)
+			goto out;
+
 		/* As long as this node is not registered with the SCSI
 		 * or NVMe transport and no other PRLIs are outstanding,
 		 * it is no longer an active node.  Otherwise devloss