scsi: lpfc: Defer LS_ACC to FLOGI on point to point logins

The current discovery state machine the driver treated FLOGI oddly.  When
point to point, an FLOGI is to be exchanged by the two ports, with the port
with the most significant WWN then proceeding with PLOGI.  The
implementation in the driver was keyed to closely with "what have I sent",
not with what has happened between the two endpoints. Thus, it blatantly
would ACC an FLOGI, but reject PLOGI's until it had its FLOGI ACC'd. The
problem is - the sending of FLOGI may be delayed for some reason, or the
response to FLOGI held off by the other side. In the failing situation the
other side sent an FLOGI, which was ACC'd, then sent PLOGIs which were then
rjt'd until the retry count for the PLOGIs were exceeded and the port gave
up. The FLOGI may have been very late in transmit, or the response held off
until the PLOGIs failed. Given the other port had the higher WWN, no PLOGIs
would occur and communication stopped.

Correct the situation by changing the FLOGI handling. Defer any response to
an FLOGI until the driver has sent its FLOGI as well. Then, upon either
completion of the sent FLOGI, or upon sending an ACC to a received FLOGI
(which may be received before or just after FLOGI was sent). the driver
will act on who has the higher WWN. if the other port does, the driver will
noop any handling of an FLOGI response (if outstanding) and wait for PLOGI.
If the local port does, the driver will transition to sending PLOGI and
will noop any action on responding to an FLOGI (if not yet received).

Fortunately, to implement this, it only took another state flag and
deferring any FLOGI response if the FLOGI has yet to be transmit. All
subsequent actions were already in place.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc.h

@@ -731,6 +731,7 @@ struct lpfc_hba {
 					 * capability
 					 */
 #define HBA_NVME_IOQ_FLUSH      0x80000 /* NVME IO queues flushed. */
+#define HBA_FLOGI_ISSUED	0x100000 /* FLOGI was issued */
 
 	uint32_t fcp_ring_in_use; /* When polling test if intr-hndlr active*/
 	struct lpfc_dmabuf slim2p;
@@ -1127,6 +1128,10 @@ struct lpfc_hba {
 	uint16_t vlan_id;
 	struct list_head fcf_conn_rec_list;
 
+	bool defer_flogi_acc_flag;
+	uint16_t defer_flogi_acc_rx_id;
+	uint16_t defer_flogi_acc_ox_id;
+
 	spinlock_t ct_ev_lock; /* synchronize access to ct_ev_waiters */
 	struct list_head ct_ev_waiters;
 	struct unsol_rcv_ct_ctx ct_ctx[LPFC_CT_CTX_MAX];

drivers/scsi/lpfc/lpfc_els.c

@@ -1234,9 +1234,10 @@ lpfc_issue_els_flogi(struct lpfc_vport *vport, struct lpfc_nodelist *ndlp,
 	struct serv_parm *sp;
 	IOCB_t *icmd;
 	struct lpfc_iocbq *elsiocb;
+	struct lpfc_iocbq defer_flogi_acc;
 	uint8_t *pcmd;
 	uint16_t cmdsize;
-	uint32_t tmo;
+	uint32_t tmo, did;
 	int rc;
 
 	cmdsize = (sizeof(uint32_t) + sizeof(struct serv_parm));
@@ -1308,6 +1309,35 @@ lpfc_issue_els_flogi(struct lpfc_vport *vport, struct lpfc_nodelist *ndlp,
 		phba->sli3_options, 0, 0);
 
 	rc = lpfc_issue_fabric_iocb(phba, elsiocb);
+
+	phba->hba_flag |= HBA_FLOGI_ISSUED;
+
+	/* Check for a deferred FLOGI ACC condition */
+	if (phba->defer_flogi_acc_flag) {
+		did = vport->fc_myDID;
+		vport->fc_myDID = Fabric_DID;
+
+		memset(&defer_flogi_acc, 0, sizeof(struct lpfc_iocbq));
+
+		defer_flogi_acc.iocb.ulpContext = phba->defer_flogi_acc_rx_id;
+		defer_flogi_acc.iocb.unsli3.rcvsli3.ox_id =
+						phba->defer_flogi_acc_ox_id;
+
+		lpfc_printf_vlog(vport, KERN_INFO, LOG_ELS,
+				 "3354 Xmit deferred FLOGI ACC: rx_id: x%x,"
+				 " ox_id: x%x, hba_flag x%x\n",
+				 phba->defer_flogi_acc_rx_id,
+				 phba->defer_flogi_acc_ox_id, phba->hba_flag);
+
+		/* Send deferred FLOGI ACC */
+		lpfc_els_rsp_acc(vport, ELS_CMD_FLOGI, &defer_flogi_acc,
+				 ndlp, NULL);
+
+		phba->defer_flogi_acc_flag = false;
+
+		vport->fc_myDID = did;
+	}
+
 	if (rc == IOCB_ERROR) {
 		lpfc_els_free_iocb(phba, elsiocb);
 		return 1;
@@ -6662,6 +6692,25 @@ lpfc_els_rcv_flogi(struct lpfc_vport *vport, struct lpfc_iocbq *cmdiocb,
 
 	memcpy(&phba->fc_fabparam, sp, sizeof(struct serv_parm));
 
+	/* Defer ACC response until AFTER we issue a FLOGI */
+	if (!(phba->hba_flag & HBA_FLOGI_ISSUED)) {
+		phba->defer_flogi_acc_rx_id = cmdiocb->iocb.ulpContext;
+		phba->defer_flogi_acc_ox_id =
+					cmdiocb->iocb.unsli3.rcvsli3.ox_id;
+
+		vport->fc_myDID = did;
+
+		lpfc_printf_vlog(vport, KERN_INFO, LOG_ELS,
+				 "3344 Deferring FLOGI ACC: rx_id: x%x,"
+				 " ox_id: x%x, hba_flag x%x\n",
+				 phba->defer_flogi_acc_rx_id,
+				 phba->defer_flogi_acc_ox_id, phba->hba_flag);
+
+		phba->defer_flogi_acc_flag = true;
+
+		return 0;
+	}
+
 	/* Send back ACC */
 	lpfc_els_rsp_acc(vport, ELS_CMD_FLOGI, cmdiocb, ndlp, NULL);
 
@@ -8133,9 +8182,10 @@ lpfc_els_unsol_buffer(struct lpfc_hba *phba, struct lpfc_sli_ring *pring,
 			cmd, did, vport->port_state, vport->fc_flag,
 			vport->fc_myDID, vport->fc_prevDID);
 
-	/* reject till our FLOGI completes */
+	/* reject till our FLOGI completes or PLOGI assigned DID via PT2PT */
 	if ((vport->port_state < LPFC_FABRIC_CFG_LINK) &&
-	    (cmd != ELS_CMD_FLOGI)) {
+	    (cmd != ELS_CMD_FLOGI) &&
+	    !((cmd == ELS_CMD_PLOGI) && (vport->fc_flag & FC_PT2PT))) {
 		rjt_err = LSRJT_LOGICAL_BSY;
 		rjt_exp = LSEXP_NOTHING_MORE;
 		goto lsrjt;

drivers/scsi/lpfc/lpfc_hbadisc.c

@@ -894,6 +894,8 @@ lpfc_linkdown(struct lpfc_hba *phba)
 	/* Block all SCSI stack I/Os */
 	lpfc_scsi_dev_block(phba);
 
+	phba->defer_flogi_acc_flag = false;
+
 	spin_lock_irq(&phba->hbalock);
 	phba->fcf.fcf_flag &= ~(FCF_AVAILABLE | FCF_SCAN_DONE);
 	spin_unlock_irq(&phba->hbalock);
@@ -1040,6 +1042,11 @@ lpfc_linkup(struct lpfc_hba *phba)
 	spin_lock_irq(shost->host_lock);
 	phba->pport->rcv_flogi_cnt = 0;
 	spin_unlock_irq(shost->host_lock);
+
+	/* reinitialize initial FLOGI flag */
+	phba->hba_flag &= ~(HBA_FLOGI_ISSUED);
+	phba->defer_flogi_acc_flag = false;
+
 	return 0;
 }