cpumask: use cpumask_var_t in dcdbas.c

Impact: reduce stack usage.

Replace cpumask_t with cpumask_var_t in drivers/firmware/dcdbas.c.
Signed-off-by: Mike Travis <travis@sgi.com>

drivers/firmware/dcdbas.c

@@ -244,7 +244,7 @@ static ssize_t host_control_on_shutdown_store(struct device *dev,
  */
 int dcdbas_smi_request(struct smi_cmd *smi_cmd)
 {
-	cpumask_t old_mask;
+	cpumask_var_t old_mask;
 	int ret = 0;
 
 	if (smi_cmd->magic != SMI_CMD_MAGIC) {
@@ -254,8 +254,11 @@ int dcdbas_smi_request(struct smi_cmd *smi_cmd)
 	}
 
 	/* SMI requires CPU 0 */
-	old_mask = current->cpus_allowed;
-	set_cpus_allowed_ptr(current, &cpumask_of_cpu(0));
+	if (!alloc_cpumask_var(&old_mask, GFP_KERNEL))
+		return -ENOMEM;
+
+	cpumask_copy(old_mask, &current->cpus_allowed);
+	set_cpus_allowed_ptr(current, cpumask_of(0));
 	if (smp_processor_id() != 0) {
 		dev_dbg(&dcdbas_pdev->dev, "%s: failed to get CPU 0\n",
 			__func__);
@@ -275,7 +278,8 @@ int dcdbas_smi_request(struct smi_cmd *smi_cmd)
 	);
 
 out:
-	set_cpus_allowed_ptr(current, &old_mask);
+	set_cpus_allowed_ptr(current, old_mask);
+	free_cpumask_var(old_mask);
 	return ret;
 }