lpfc: Fix to drop PLOGIs from fabric node till LOGO processing completes

The domain controller PLOGI's concurrent with prior LOGO's/unreg_rpi's
completing created a race condition where driver rpi ref count can
inadvertantly hit 0 and the rpi attempted to be freed. This error
sometimes resulted in Warning messages indicating kref.h via
lfpc_nlp_get+0x128.

Correct by dropping any new PLOGI until the prior nport state has settled.

Signed-off-by: Dick Kennedy <dick.kennedy@avagotech.com>
Signed-off-by: James Smart <james.smart@avagotech.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

drivers/scsi/lpfc/lpfc_hbadisc.c

@@ -4495,7 +4495,7 @@ lpfc_unreg_rpi(struct lpfc_vport *vport, struct lpfc_nodelist *ndlp)
 {
 	struct lpfc_hba *phba = vport->phba;
 	LPFC_MBOXQ_t    *mbox;
-	int rc;
+	int rc, acc_plogi = 1;
 	uint16_t rpi;
 
 	if (ndlp->nlp_flag & NLP_RPI_REGISTERED ||
@@ -4528,14 +4528,20 @@ lpfc_unreg_rpi(struct lpfc_vport *vport, struct lpfc_nodelist *ndlp)
 					mbox->context1 = lpfc_nlp_get(ndlp);
 					mbox->mbox_cmpl =
 						lpfc_sli4_unreg_rpi_cmpl_clr;
+					/*
+					 * accept PLOGIs after unreg_rpi_cmpl
+					 */
+					acc_plogi = 0;
 				} else
 					mbox->mbox_cmpl =
 						lpfc_sli_def_mbox_cmpl;
 			}
 
 			rc = lpfc_sli_issue_mbox(phba, mbox, MBX_NOWAIT);
-			if (rc == MBX_NOT_FINISHED)
+			if (rc == MBX_NOT_FINISHED) {
 				mempool_free(mbox, phba->mbox_mem_pool);
+				acc_plogi = 1;
+			}
 		}
 		lpfc_no_rpi(phba, ndlp);
 
@@ -4543,8 +4549,11 @@ lpfc_unreg_rpi(struct lpfc_vport *vport, struct lpfc_nodelist *ndlp)
 			ndlp->nlp_rpi = 0;
 		ndlp->nlp_flag &= ~NLP_RPI_REGISTERED;
 		ndlp->nlp_flag &= ~NLP_NPR_ADISC;
+		if (acc_plogi)
+			ndlp->nlp_flag &= ~NLP_LOGO_ACC;
 		return 1;
 	}
+	ndlp->nlp_flag &= ~NLP_LOGO_ACC;
 	return 0;
 }