bfa: Fix for crash when bfa_itnim is NULL

Fix a very corner case when the port gets disconnected and the BFA and
FCS layers clean up references to the IT nexus.  During this window if a
task management command is issued by the SCSI-ML and ends up referencing
a NULL itnim, it could lead to a crash.
Signed-off-by: Sudarsana Kalluru <sudarsana.kalluru@qlogic.com>
Signed-off-by: Anil Gurumurthy <anil.gurumurthy@qlogic.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/bfa/bfad_im.c

@@ -272,6 +272,19 @@ bfad_im_target_reset_send(struct bfad_s *bfad, struct scsi_cmnd *cmnd,
 	cmnd->host_scribble = NULL;
 	cmnd->SCp.Status = 0;
 	bfa_itnim = bfa_fcs_itnim_get_halitn(&itnim->fcs_itnim);
+	/*
+	 * bfa_itnim can be NULL if the port gets disconnected and the bfa
+	 * and fcs layers have cleaned up their nexus with the targets and
+	 * the same has not been cleaned up by the shim
+	 */
+	if (bfa_itnim == NULL) {
+		bfa_tskim_free(tskim);
+		BFA_LOG(KERN_ERR, bfad, bfa_log_level,
+			"target reset, bfa_itnim is NULL\n");
+		rc = BFA_STATUS_FAILED;
+		goto out;
+	}
+
 	memset(&scsilun, 0, sizeof(scsilun));
 	bfa_tskim_start(tskim, bfa_itnim, scsilun,
 			    FCP_TM_TARGET_RESET, BFAD_TARGET_RESET_TMO);
@@ -327,6 +340,19 @@ bfad_im_reset_lun_handler(struct scsi_cmnd *cmnd)
 	cmnd->SCp.ptr = (char *)&wq;
 	cmnd->SCp.Status = 0;
 	bfa_itnim = bfa_fcs_itnim_get_halitn(&itnim->fcs_itnim);
+	/*
+	 * bfa_itnim can be NULL if the port gets disconnected and the bfa
+	 * and fcs layers have cleaned up their nexus with the targets and
+	 * the same has not been cleaned up by the shim
+	 */
+	if (bfa_itnim == NULL) {
+		bfa_tskim_free(tskim);
+		BFA_LOG(KERN_ERR, bfad, bfa_log_level,
+			"lun reset, bfa_itnim is NULL\n");
+		spin_unlock_irqrestore(&bfad->bfad_lock, flags);
+		rc = FAILED;
+		goto out;
+	}
 	int_to_scsilun(cmnd->device->lun, &scsilun);
 	bfa_tskim_start(tskim, bfa_itnim, scsilun,
 			    FCP_TM_LUN_RESET, BFAD_LUN_RESET_TMO);