scsi: lpfc: Ensure PLOGI_ACC is sent prior to PRLI in Point to Point topology

There is a timing race condition when a PRLI may be sent on the wire
before PLOGI_ACC in Point to Point topology.  Fix by deferring REG_RPI
mbox completion handling to after PLOGI_ACC's CQE completion.  Because
the discovery state machine only sends PRLI after REG_RPI mbox
completion, PRLI is now guaranteed to be sent after PLOGI_ACC.

Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Message-ID: <20250915180811.137530-8-justintee8345@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: Justin Tee

drivers/scsi/lpfc/lpfc_els.c

@@ -5339,12 +5339,12 @@ lpfc_cmpl_els_rsp(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 		ulp_status, ulp_word4, did);
 	/* ELS response tag <ulpIoTag> completes */
 	lpfc_printf_vlog(vport, KERN_INFO, LOG_ELS,
-			 "0110 ELS response tag x%x completes "
+			 "0110 ELS response tag x%x completes fc_flag x%lx"
 			 "Data: x%x x%x x%x x%x x%lx x%x x%x x%x %p %p\n",
-			 iotag, ulp_status, ulp_word4, tmo,
+			 iotag, vport->fc_flag, ulp_status, ulp_word4, tmo,
 			 ndlp->nlp_DID, ndlp->nlp_flag, ndlp->nlp_state,
 			 ndlp->nlp_rpi, kref_read(&ndlp->kref), mbox, ndlp);
-	if (mbox) {
+	if (mbox && !test_bit(FC_PT2PT, &vport->fc_flag)) {
 		if (ulp_status == 0 &&
 		    test_bit(NLP_ACC_REGLOGIN, &ndlp->nlp_flag)) {
 			if (!lpfc_unreg_rpi(vport, ndlp) &&
@@ -5403,6 +5403,10 @@ lpfc_cmpl_els_rsp(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 		}
 out_free_mbox:
 		lpfc_mbox_rsrc_cleanup(phba, mbox, MBOX_THD_UNLOCKED);
+	} else if (mbox && test_bit(FC_PT2PT, &vport->fc_flag) &&
+		   test_bit(NLP_ACC_REGLOGIN, &ndlp->nlp_flag)) {
+		lpfc_mbx_cmpl_reg_login(phba, mbox);
+		clear_bit(NLP_ACC_REGLOGIN, &ndlp->nlp_flag);
 	}
 out:
 	if (ndlp && shost) {

drivers/scsi/lpfc/lpfc_nportdisc.c

@@ -326,18 +326,31 @@ lpfc_defer_plogi_acc(struct lpfc_hba *phba, LPFC_MBOXQ_t *login_mbox)
 		/* Now that REG_RPI completed successfully,
 		 * we can now proceed with sending the PLOGI ACC.
 		 */
-		rc = lpfc_els_rsp_acc(login_mbox->vport, ELS_CMD_PLOGI,
-				      save_iocb, ndlp, NULL);
+		if (test_bit(FC_PT2PT, &ndlp->vport->fc_flag)) {
+			rc = lpfc_els_rsp_acc(login_mbox->vport, ELS_CMD_PLOGI,
+					      save_iocb, ndlp, login_mbox);
+		} else {
+			rc = lpfc_els_rsp_acc(login_mbox->vport, ELS_CMD_PLOGI,
+					      save_iocb, ndlp, NULL);
+		}
+
 		if (rc) {
 			lpfc_printf_log(phba, KERN_ERR, LOG_TRACE_EVENT,
 					"4576 PLOGI ACC fails pt2pt discovery: "
 					"DID %x Data: %x\n", ndlp->nlp_DID, rc);
 		}
 	}
 
-	/* Now process the REG_RPI cmpl */
-	lpfc_mbx_cmpl_reg_login(phba, login_mbox);
-	clear_bit(NLP_ACC_REGLOGIN, &ndlp->nlp_flag);
+	/* If this is a fabric topology, complete the reg_rpi and prli now.
+	 * For Pt2Pt, the reg_rpi and PRLI are deferred until after the LS_ACC
+	 * completes.  This ensures, in Pt2Pt, that the PLOGI LS_ACC is sent
+	 * before the PRLI.
+	 */
+	if (!test_bit(FC_PT2PT, &ndlp->vport->fc_flag)) {
+		/* Now process the REG_RPI cmpl */
+		lpfc_mbx_cmpl_reg_login(phba, login_mbox);
+		clear_bit(NLP_ACC_REGLOGIN, &ndlp->nlp_flag);
+	}
 	kfree(save_iocb);
 }