ARM: cpuidle: Refactor rollback operations if init fails

If init fails, we need execute two levels rollback operations: the first
level is for the failed CPU rollback operations, the second level is to
iterate all succeeded CPUs to cancel their registration; currently the
code uses one function to finish these two levels rollback operations.

This commit is to refactor rollback operations, so it adds a new
function arm_idle_init_cpu() to encapsulate one specified CPU driver
registration and rollback the first level operations; and use function
arm_idle_init() to iterate all CPUs and finish the second level's
rollback operations.
Suggested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpuidle/cpuidle-arm.c

@@ -72,25 +72,21 @@ static const struct of_device_id arm_idle_state_match[] __initconst = {
 };
 
 /*
- * arm_idle_init
+ * arm_idle_init_cpu
  *
  * Registers the arm specific cpuidle driver with the cpuidle
  * framework. It relies on core code to parse the idle states
  * and initialize them using driver data structures accordingly.
  */
-static int __init arm_idle_init(void)
+static int __init arm_idle_init_cpu(int cpu)
 {
-	int cpu, ret;
+	int ret;
 	struct cpuidle_driver *drv;
 	struct cpuidle_device *dev;
 
-	for_each_possible_cpu(cpu) {
-
 	drv = kmemdup(&arm_idle_driver, sizeof(*drv), GFP_KERNEL);
-		if (!drv) {
-			ret = -ENOMEM;
-			goto out_fail;
-		}
+	if (!drv)
+		return -ENOMEM;
 
 	drv->cpumask = (struct cpumask *)cpumask_of(cpu);
 
@@ -124,7 +120,7 @@ static int __init arm_idle_init(void)
 	 * failure is a HW misconfiguration/breakage (-ENXIO).
 	 */
 	if (ret == -ENXIO)
-			continue;
+		return 0;
 
 	if (ret) {
 		pr_err("CPU %d failed to init idle CPU ops\n", cpu);
@@ -145,7 +141,6 @@ static int __init arm_idle_init(void)
 		       cpu);
 		goto out_kfree_dev;
 	}
-	}
 
 	return 0;
 
@@ -155,6 +150,30 @@ static int __init arm_idle_init(void)
 	cpuidle_unregister_driver(drv);
 out_kfree_drv:
 	kfree(drv);
+	return ret;
+}
+
+/*
+ * arm_idle_init - Initializes arm cpuidle driver
+ *
+ * Initializes arm cpuidle driver for all CPUs, if any CPU fails
+ * to register cpuidle driver then rollback to cancel all CPUs
+ * registeration.
+ */
+static int __init arm_idle_init(void)
+{
+	int cpu, ret;
+	struct cpuidle_driver *drv;
+	struct cpuidle_device *dev;
+
+	for_each_possible_cpu(cpu) {
+		ret = arm_idle_init_cpu(cpu);
+		if (ret)
+			goto out_fail;
+	}
+
+	return 0;
+
 out_fail:
 	while (--cpu >= 0) {
 		dev = per_cpu(cpuidle_devices, cpu);