scsi_dh_rdac: switch to scsi_execute_req_flags()

Hello Hannes Reinecke,

The patch 327825574132: "scsi_dh_rdac: switch to scsi_execute_req_flags()" from Nov 3, 2016, leads to the following static checker warning:

	drivers/scsi/device_handler/scsi_dh_rdac.c:551 send_mode_select()
	error: potential NULL dereference 'ctlr->ms_sdev'.

drivers/scsi/device_handler/scsi_dh_rdac.c
529 static void send_mode_select(struct work_struct *work) 530 {
531 struct rdac_controller *ctlr =
532 container_of(work, struct rdac_controller, ms_work);

   533          struct scsi_device *sdev = ctlr->ms_sdev;
   534          struct rdac_dh_data *h = sdev->handler_data;
   535          int err = SCSI_DH_OK, retry_cnt = RDAC_RETRY_COUNT;
   536          struct rdac_queue_data *tmp, *qdata;
   537          LIST_HEAD(list);
   538          unsigned char cdb[COMMAND_SIZE(MODE_SELECT_10)];
   539          struct scsi_sense_hdr sshdr;
   540          unsigned int data_size;
   541          u64 req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
   542                  REQ_FAILFAST_DRIVER;
   543  
   544          spin_lock(&ctlr->ms_lock);
   545          list_splice_init(&ctlr->ms_head, &list);
   546          ctlr->ms_queued = 0;
   547          ctlr->ms_sdev = NULL;
                ^^^^^^^^^^^^^^^^^^^^

We set this to NULL.

548 spin_unlock(&ctlr->ms_lock);
549
550 retry:

   551          data_size = rdac_failover_get(ctlr, &list, cdb);
                                              ^^^^

Then dereference it here inside this function.

552
553 RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, "

   554                  "%s MODE_SELECT command",
   555                  (char *) h->ctlr->array_name, h->ctlr->index,
   556                  (retry_cnt == RDAC_RETRY_COUNT) ? "queueing" : "retrying");

557

regards,
dan carpenter