[PATCH v2 2/2] ARM: cpuidle: Refactor rollback operations if init fails

[Leo Yan]

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@xxxxxxxxxx>
Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
---
 drivers/cpuidle/cpuidle-arm.c | 145 ++++++++++++++++++++++++------------------
 1 file changed, 82 insertions(+), 63 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
index f47c545..ddee1b6 100644
--- a/drivers/cpuidle/cpuidle-arm.c
+++ b/drivers/cpuidle/cpuidle-arm.c
@@ -72,79 +72,74 @@ 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)
+		return -ENOMEM;
 
-		drv = kmemdup(&arm_idle_driver, sizeof(*drv), GFP_KERNEL);
-		if (!drv) {
-			ret = -ENOMEM;
-			goto out_fail;
-		}
-
-		drv->cpumask = (struct cpumask *)cpumask_of(cpu);
-
-		/*
-		 * Initialize idle states data, starting at index 1.  This
-		 * driver is DT only, if no DT idle states are detected (ret
-		 * == 0) let the driver initialization fail accordingly since
-		 * there is no reason to initialize the idle driver if only
-		 * wfi is supported.
-		 */
-		ret = dt_init_idle_driver(drv, arm_idle_state_match, 1);
-		if (ret <= 0) {
-			ret = ret ? : -ENODEV;
-			goto out_kfree_drv;
-		}
-
-		ret = cpuidle_register_driver(drv);
-		if (ret) {
-			pr_err("Failed to register cpuidle driver\n");
-			goto out_kfree_drv;
-		}
-
-		/*
-		 * Call arch CPU operations in order to initialize
-		 * idle states suspend back-end specific data
-		 */
-		ret = arm_cpuidle_init(cpu);
-
-		/*
-		 * Skip the cpuidle device initialization if the reported
-		 * failure is a HW misconfiguration/breakage (-ENXIO).
-		 */
-		if (ret == -ENXIO)
-			continue;
-
-		if (ret) {
-			pr_err("CPU %d failed to init idle CPU ops\n", cpu);
-			goto out_unregister_drv;
-		}
-
-		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
-		if (!dev) {
-			pr_err("Failed to allocate cpuidle device\n");
-			ret = -ENOMEM;
-			goto out_unregister_drv;
-		}
-		dev->cpu = cpu;
-
-		ret = cpuidle_register_device(dev);
-		if (ret) {
-			pr_err("Failed to register cpuidle device for CPU %d\n",
-			       cpu);
-			goto out_kfree_dev;
-		}
+	drv->cpumask = (struct cpumask *)cpumask_of(cpu);
+
+	/*
+	 * Initialize idle states data, starting at index 1.  This
+	 * driver is DT only, if no DT idle states are detected (ret
+	 * == 0) let the driver initialization fail accordingly since
+	 * there is no reason to initialize the idle driver if only
+	 * wfi is supported.
+	 */
+	ret = dt_init_idle_driver(drv, arm_idle_state_match, 1);
+	if (ret <= 0) {
+		ret = ret ? : -ENODEV;
+		goto out_kfree_drv;
+	}
+
+	ret = cpuidle_register_driver(drv);
+	if (ret) {
+		pr_err("Failed to register cpuidle driver\n");
+		goto out_kfree_drv;
+	}
+
+	/*
+	 * Call arch CPU operations in order to initialize
+	 * idle states suspend back-end specific data
+	 */
+	ret = arm_cpuidle_init(cpu);
+
+	/*
+	 * Skip the cpuidle device initialization if the reported
+	 * failure is a HW misconfiguration/breakage (-ENXIO).
+	 */
+	if (ret == -ENXIO)
+		return 0;
+
+	if (ret) {
+		pr_err("CPU %d failed to init idle CPU ops\n", cpu);
+		goto out_unregister_drv;
+	}
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev) {
+		pr_err("Failed to allocate cpuidle device\n");
+		ret = -ENOMEM;
+		goto out_unregister_drv;
+	}
+	dev->cpu = cpu;
+
+	ret = cpuidle_register_device(dev);
+	if (ret) {
+		pr_err("Failed to register cpuidle device for CPU %d\n",
+		       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);
-- 
2.7.4