scsi: megaraid_sas: add correct return type check for ldio hint logic for raid1

Return value check of atomic_dec_if_positive is required as it returns
old value minus one.  Without this fix, driver will send small ios to
firmware path and that will be a performance issue.

Not critical, but good to have r1_ldio_hint as default value in sdev
private.
Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/megaraid/megaraid_sas_base.c

@@ -1963,6 +1963,9 @@ static int megasas_slave_alloc(struct scsi_device *sdev)
 	if (!mr_device_priv_data)
 		return -ENOMEM;
 	sdev->hostdata = mr_device_priv_data;
+
+	atomic_set(&mr_device_priv_data->r1_ldio_hint,
+		   instance->r1_ldio_hint_default);
 	return 0;
 }
 

drivers/scsi/megaraid/megaraid_sas_fusion.c

@@ -2338,7 +2338,7 @@ megasas_build_ldio_fusion(struct megasas_instance *instance,
 				fp_possible = false;
 				atomic_dec(&instance->fw_outstanding);
 			} else if ((scsi_buff_len > MR_LARGE_IO_MIN_SIZE) ||
-				   atomic_dec_if_positive(&mrdev_priv->r1_ldio_hint)) {
+				   (atomic_dec_if_positive(&mrdev_priv->r1_ldio_hint) > 0)) {
 				fp_possible = false;
 				atomic_dec(&instance->fw_outstanding);
 				if (scsi_buff_len > MR_LARGE_IO_MIN_SIZE)