scsi: lpfc: Fix system crash when port is reset.

The driver panic when using the els_wq during port reset.

Check for NULL els_wq before dereferencing.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc.h

@@ -1228,7 +1228,11 @@ lpfc_sli_read_hs(struct lpfc_hba *phba)
 static inline struct lpfc_sli_ring *
 lpfc_phba_elsring(struct lpfc_hba *phba)
 {
-	if (phba->sli_rev == LPFC_SLI_REV4)
+	if (phba->sli_rev == LPFC_SLI_REV4) {
+		if (phba->sli4_hba.els_wq)
 			return phba->sli4_hba.els_wq->pring;
+		else
+			return NULL;
+	}
 	return &phba->sli.sli3_ring[LPFC_ELS_RING];
 }

drivers/scsi/lpfc/lpfc_hbadisc.c

@@ -693,9 +693,9 @@ lpfc_work_done(struct lpfc_hba *phba)
 	pring = lpfc_phba_elsring(phba);
 	status = (ha_copy & (HA_RXMASK  << (4*LPFC_ELS_RING)));
 	status >>= (4*LPFC_ELS_RING);
-	if ((status & HA_RXMASK) ||
-	    (pring->flag & LPFC_DEFERRED_RING_EVENT) ||
-	    (phba->hba_flag & HBA_SP_QUEUE_EVT)) {
+	if (pring && (status & HA_RXMASK ||
+		      pring->flag & LPFC_DEFERRED_RING_EVENT ||
+		      phba->hba_flag & HBA_SP_QUEUE_EVT)) {
 		if (pring->flag & LPFC_STOP_IOCB_EVENT) {
 			pring->flag |= LPFC_DEFERRED_RING_EVENT;
 			/* Set the lpfc data pending flag */