[PATCH 4/6] lpfc: Fix crash involving race between FLOGI timeout and devloss handler

[Justin Tee <justintee8345@gmail.com>]

When a FLOGI completes with a sequence timeout error, a freed kref ptr
dereference crash can occur due to a timing race involving ndlp referencing
in lpfc_dev_loss_tmo_callbk.

Fix by ensuring the driver accounts for an outstanding FLOGI when dev_loss
is active.  Also, don't remove the HBA_FLOGI_OUTSTANDING flag when the
FLOGI is retried to allow the driver to handle the reference counts
correctly in lpfc_dev_loss_tmo_handler.

Reported-by: Dietmar Hahn <dietmar.hahn@fujitsu.com>
Tested-by: Dietmar Hahn <dietmar.hahn@fujitsu.com>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
---
 drivers/scsi/lpfc/lpfc_els.c     | 36 +++++++++++++++++++++++++++-----
 drivers/scsi/lpfc/lpfc_hbadisc.c | 36 +++++++++++++++++++++++---------
 2 files changed, 57 insertions(+), 15 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_els.c b/drivers/scsi/lpfc/lpfc_els.c
index 2b03210264bb..1b541d2cf827 100644
--- a/drivers/scsi/lpfc/lpfc_els.c
+++ b/drivers/scsi/lpfc/lpfc_els.c
@@ -952,6 +952,7 @@ lpfc_cmpl_els_flogi(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 	uint16_t fcf_index;
 	int rc;
 	u32 ulp_status, ulp_word4, tmo;
+	bool flogi_in_retry = false;
 
 	/* Check to see if link went down during discovery */
 	if (lpfc_els_chk_latt(vport)) {
@@ -1022,8 +1023,23 @@ lpfc_cmpl_els_flogi(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 					 phba->hba_flag, phba->fcf.fcf_flag);
 
 		/* Check for retry */
-		if (lpfc_els_retry(phba, cmdiocb, rspiocb))
+		if (lpfc_els_retry(phba, cmdiocb, rspiocb)) {
+			/* Address a timing race with dev_loss.  If dev_loss
+			 * is active on this FPort node, put the initial ref
+			 * count back to stop premature node release actions.
+			 */
+			lpfc_check_nlp_post_devloss(vport, ndlp);
+			flogi_in_retry = true;
 			goto out;
+		}
+
+		/* The FLOGI will not be retried.  If the FPort node is not
+		 * registered with the SCSI transport, remove the initial
+		 * reference to trigger node release.
+		 */
+		if (!(ndlp->nlp_flag & NLP_IN_DEV_LOSS) &&
+		    !(ndlp->fc4_xpt_flags & SCSI_XPT_REGD))
+			lpfc_nlp_put(ndlp);
 
 		lpfc_printf_vlog(vport, KERN_WARNING, LOG_TRACE_EVENT,
 				 "0150 FLOGI failure Status:x%x/x%x "
@@ -1086,7 +1102,7 @@ lpfc_cmpl_els_flogi(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 	spin_unlock_irq(shost->host_lock);
 
 	/*
-	 * The FLogI succeeded.  Sync the data for the CPU before
+	 * The FLOGI succeeded.  Sync the data for the CPU before
 	 * accessing it.
 	 */
 	prsp = list_get_first(&pcmd->list, struct lpfc_dmabuf, list);
@@ -1108,6 +1124,12 @@ lpfc_cmpl_els_flogi(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 		vport->phba->pport->vmid_flag |= (LPFC_VMID_ISSUE_QFPA |
 						  LPFC_VMID_TYPE_PRIO);
 
+	/*
+	 * Address a timing race with dev_loss.  If dev_loss is active on
+	 * this FPort node, put the initial ref count back to stop premature
+	 * node release actions.
+	 */
+	lpfc_check_nlp_post_devloss(vport, ndlp);
 	if (vport->port_state == LPFC_FLOGI) {
 		/*
 		 * If Common Service Parameters indicate Nport
@@ -1198,7 +1220,9 @@ lpfc_cmpl_els_flogi(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 		lpfc_issue_clear_la(phba, vport);
 	}
 out:
-	phba->hba_flag &= ~HBA_FLOGI_OUTSTANDING;
+	if (!flogi_in_retry)
+		phba->hba_flag &= ~HBA_FLOGI_OUTSTANDING;
+
 	lpfc_els_free_iocb(phba, cmdiocb);
 	lpfc_nlp_put(ndlp);
 }
@@ -1365,15 +1389,17 @@ lpfc_issue_els_flogi(struct lpfc_vport *vport, struct lpfc_nodelist *ndlp,
 		return 1;
 	}
 
+	/* Avoid race with FLOGI completion and hba_flags. */
+	phba->hba_flag |= (HBA_FLOGI_ISSUED | HBA_FLOGI_OUTSTANDING);
+
 	rc = lpfc_issue_fabric_iocb(phba, elsiocb);
 	if (rc == IOCB_ERROR) {
+		phba->hba_flag &= ~(HBA_FLOGI_ISSUED | HBA_FLOGI_OUTSTANDING);
 		lpfc_els_free_iocb(phba, elsiocb);
 		lpfc_nlp_put(ndlp);
 		return 1;
 	}
 
-	phba->hba_flag |= (HBA_FLOGI_ISSUED | HBA_FLOGI_OUTSTANDING);
-
 	/* Clear external loopback plug detected flag */
 	phba->link_flag &= ~LS_EXTERNAL_LOOPBACK;
 
diff --git a/drivers/scsi/lpfc/lpfc_hbadisc.c b/drivers/scsi/lpfc/lpfc_hbadisc.c
index d38ebd7281b9..80375d73b732 100644
--- a/drivers/scsi/lpfc/lpfc_hbadisc.c
+++ b/drivers/scsi/lpfc/lpfc_hbadisc.c
@@ -426,10 +426,6 @@ lpfc_dev_loss_tmo_handler(struct lpfc_nodelist *ndlp)
 	name = (uint8_t *)&ndlp->nlp_portname;
 	phba = vport->phba;
 
-	spin_lock_irqsave(&ndlp->lock, iflags);
-	ndlp->nlp_flag &= ~NLP_IN_DEV_LOSS;
-	spin_unlock_irqrestore(&ndlp->lock, iflags);
-
 	if (phba->sli_rev == LPFC_SLI_REV4)
 		fcf_inuse = lpfc_fcf_inuse(phba);
 
@@ -451,22 +447,36 @@ lpfc_dev_loss_tmo_handler(struct lpfc_nodelist *ndlp)
 				 *name, *(name+1), *(name+2), *(name+3),
 				 *(name+4), *(name+5), *(name+6), *(name+7),
 				 ndlp->nlp_DID);
+
+		spin_lock_irqsave(&ndlp->lock, iflags);
+		ndlp->nlp_flag &= ~NLP_IN_DEV_LOSS;
+		spin_unlock_irqrestore(&ndlp->lock, iflags);
 		return fcf_inuse;
 	}
 
 	/* Fabric nodes are done. */
 	if (ndlp->nlp_type & NLP_FABRIC) {
 		spin_lock_irqsave(&ndlp->lock, iflags);
-		/* In massive vport configuration settings, it's possible
-		 * dev_loss_tmo fired during node recovery.  So, check if
-		 * fabric nodes are in discovery states outstanding.
+
+		/* In massive vport configuration settings or when the FLOGI
+		 * completes with a sequence timeout, it's possible
+		 * dev_loss_tmo fired during node recovery.  The driver has to
+		 * account for this race to allow for recovery and keep
+		 * the reference counting correct.
 		 */
 		switch (ndlp->nlp_DID) {
 		case Fabric_DID:
 			fc_vport = vport->fc_vport;
-			if (fc_vport &&
-			    fc_vport->vport_state == FC_VPORT_INITIALIZING)
-				recovering = true;
+			if (fc_vport) {
+				/* NPIV path. */
+				if (fc_vport->vport_state ==
+				    FC_VPORT_INITIALIZING)
+					recovering = true;
+			} else {
+				/* Physical port path. */
+				if (phba->hba_flag & HBA_FLOGI_OUTSTANDING)
+					recovering = true;
+			}
 			break;
 		case Fabric_Cntl_DID:
 			if (ndlp->nlp_flag & NLP_REG_LOGIN_SEND)
@@ -514,6 +524,9 @@ lpfc_dev_loss_tmo_handler(struct lpfc_nodelist *ndlp)
 			return fcf_inuse;
 		}
 
+		spin_lock_irqsave(&ndlp->lock, iflags);
+		ndlp->nlp_flag &= ~NLP_IN_DEV_LOSS;
+		spin_unlock_irqrestore(&ndlp->lock, iflags);
 		lpfc_nlp_put(ndlp);
 		return fcf_inuse;
 	}
@@ -552,6 +565,9 @@ lpfc_dev_loss_tmo_handler(struct lpfc_nodelist *ndlp)
 		return fcf_inuse;
 	}
 
+	spin_lock_irqsave(&ndlp->lock, iflags);
+	ndlp->nlp_flag &= ~NLP_IN_DEV_LOSS;
+	spin_unlock_irqrestore(&ndlp->lock, iflags);
 	if (!(ndlp->fc4_xpt_flags & NVME_XPT_REGD))
 		lpfc_disc_state_machine(vport, ndlp, NULL, NLP_EVT_DEVICE_RM);
 
-- 
2.38.0