Merge series "regulator: fix deadlock vs memory reclaim" from Michał …

…Mirosław <[email protected]>:

For systems that have eg. eMMC storage using voltage regulator, memory
reclaim path might call back into regulator subsystem. This means we
have to make sure no allocations happen with a regulator or regulator
list locked.

After this series I see no more lockdep complaints on my test system,
but please review and test further.

First four patches move allocations out of locked regions, next three
came as a drive-by cleanups.

---
v2: fix bug in patch #4 spotted by kernel test robot
    reworded commit #7 description

Michał Mirosław (7):
  regulator: push allocation in regulator_init_coupling() outside of
    lock
  regulator: push allocation in regulator_ena_gpio_request() out of lock
  regulator: push allocations in create_regulator() outside of lock
  regulator: push allocation in set_consumer_device_supply() out of lock
  regulator: plug of_node leak in regulator_register()'s error path
  regulator: cleanup regulator_ena_gpio_free()
  regulator: remove superfluous lock in regulator_resolve_coupling()

 drivers/regulator/core.c | 164 +++++++++++++++++++++------------------
 1 file changed, 87 insertions(+), 77 deletions(-)

--
2.20.1

drivers/regulator/core.c

@@ -1480,7 +1480,7 @@ static int set_consumer_device_supply(struct regulator_dev *rdev,
 				      const char *consumer_dev_name,
 				      const char *supply)
 {
-	struct regulator_map *node;
+	struct regulator_map *node, *new_node;
 	int has_dev;
 
 	if (supply == NULL)
@@ -1491,6 +1491,22 @@ static int set_consumer_device_supply(struct regulator_dev *rdev,
 	else
 		has_dev = 0;
 
+	new_node = kzalloc(sizeof(struct regulator_map), GFP_KERNEL);
+	if (new_node == NULL)
+		return -ENOMEM;
+
+	new_node->regulator = rdev;
+	new_node->supply = supply;
+
+	if (has_dev) {
+		new_node->dev_name = kstrdup(consumer_dev_name, GFP_KERNEL);
+		if (new_node->dev_name == NULL) {
+			kfree(new_node);
+			return -ENOMEM;
+		}
+	}
+
+	mutex_lock(&regulator_list_mutex);
 	list_for_each_entry(node, &regulator_map_list, list) {
 		if (node->dev_name && consumer_dev_name) {
 			if (strcmp(node->dev_name, consumer_dev_name) != 0)
@@ -1508,26 +1524,19 @@ static int set_consumer_device_supply(struct regulator_dev *rdev,
 			 node->regulator->desc->name,
 			 supply,
 			 dev_name(&rdev->dev), rdev_get_name(rdev));
-		return -EBUSY;
+		goto fail;
 	}
 
-	node = kzalloc(sizeof(struct regulator_map), GFP_KERNEL);
-	if (node == NULL)
-		return -ENOMEM;
-
-	node->regulator = rdev;
-	node->supply = supply;
-
-	if (has_dev) {
-		node->dev_name = kstrdup(consumer_dev_name, GFP_KERNEL);
-		if (node->dev_name == NULL) {
-			kfree(node);
-			return -ENOMEM;
-		}
-	}
+	list_add(&new_node->list, &regulator_map_list);
+	mutex_unlock(&regulator_list_mutex);
 
-	list_add(&node->list, &regulator_map_list);
 	return 0;
+
+fail:
+	mutex_unlock(&regulator_list_mutex);
+	kfree(new_node->dev_name);
+	kfree(new_node);
+	return -EBUSY;
 }
 
 static void unset_regulator_supplies(struct regulator_dev *rdev)
@@ -1599,44 +1608,53 @@ static struct regulator *create_regulator(struct regulator_dev *rdev,
 					  const char *supply_name)
 {
 	struct regulator *regulator;
-	char buf[REG_STR_SIZE];
-	int err, size;
+	int err;
+
+	if (dev) {
+		char buf[REG_STR_SIZE];
+		int size;
+
+		size = snprintf(buf, REG_STR_SIZE, "%s-%s",
+				dev->kobj.name, supply_name);
+		if (size >= REG_STR_SIZE)
+			return NULL;
+
+		supply_name = kstrdup(buf, GFP_KERNEL);
+		if (supply_name == NULL)
+			return NULL;
+	} else {
+		supply_name = kstrdup_const(supply_name, GFP_KERNEL);
+		if (supply_name == NULL)
+			return NULL;
+	}
 
 	regulator = kzalloc(sizeof(*regulator), GFP_KERNEL);
-	if (regulator == NULL)
+	if (regulator == NULL) {
+		kfree(supply_name);
 		return NULL;
+	}
 
-	regulator_lock(rdev);
 	regulator->rdev = rdev;
+	regulator->supply_name = supply_name;
+
+	regulator_lock(rdev);
 	list_add(&regulator->list, &rdev->consumer_list);
+	regulator_unlock(rdev);
 
 	if (dev) {
 		regulator->dev = dev;
 
 		/* Add a link to the device sysfs entry */
-		size = snprintf(buf, REG_STR_SIZE, "%s-%s",
-				dev->kobj.name, supply_name);
-		if (size >= REG_STR_SIZE)
-			goto overflow_err;
-
-		regulator->supply_name = kstrdup(buf, GFP_KERNEL);
-		if (regulator->supply_name == NULL)
-			goto overflow_err;
-
 		err = sysfs_create_link_nowarn(&rdev->dev.kobj, &dev->kobj,
-					buf);
+					       supply_name);
 		if (err) {
 			rdev_dbg(rdev, "could not add device link %s err %d\n",
 				  dev->kobj.name, err);
 			/* non-fatal */
 		}
-	} else {
-		regulator->supply_name = kstrdup_const(supply_name, GFP_KERNEL);
-		if (regulator->supply_name == NULL)
-			goto overflow_err;
 	}
 
-	regulator->debugfs = debugfs_create_dir(regulator->supply_name,
+	regulator->debugfs = debugfs_create_dir(supply_name,
 						rdev->debugfs);
 	if (!regulator->debugfs) {
 		rdev_dbg(rdev, "Failed to create debugfs directory\n");
@@ -1661,13 +1679,7 @@ static struct regulator *create_regulator(struct regulator_dev *rdev,
 	    _regulator_is_enabled(rdev))
 		regulator->always_on = true;
 
-	regulator_unlock(rdev);
 	return regulator;
-overflow_err:
-	list_del(&regulator->list);
-	kfree(regulator);
-	regulator_unlock(rdev);
-	return NULL;
 }
 
 static int _regulator_get_enable_time(struct regulator_dev *rdev)
@@ -2249,10 +2261,13 @@ EXPORT_SYMBOL_GPL(regulator_bulk_unregister_supply_alias);
 static int regulator_ena_gpio_request(struct regulator_dev *rdev,
 				const struct regulator_config *config)
 {
-	struct regulator_enable_gpio *pin;
+	struct regulator_enable_gpio *pin, *new_pin;
 	struct gpio_desc *gpiod;
 
 	gpiod = config->ena_gpiod;
+	new_pin = kzalloc(sizeof(*new_pin), GFP_KERNEL);
+
+	mutex_lock(&regulator_list_mutex);
 
 	list_for_each_entry(pin, &regulator_ena_gpio_list, list) {
 		if (pin->gpiod == gpiod) {
@@ -2261,16 +2276,24 @@ static int regulator_ena_gpio_request(struct regulator_dev *rdev,
 		}
 	}
 
-	pin = kzalloc(sizeof(struct regulator_enable_gpio), GFP_KERNEL);
-	if (pin == NULL)
+	if (new_pin == NULL) {
+		mutex_unlock(&regulator_list_mutex);
 		return -ENOMEM;
+	}
+
+	pin = new_pin;
+	new_pin = NULL;
 
 	pin->gpiod = gpiod;
 	list_add(&pin->list, &regulator_ena_gpio_list);
 
 update_ena_gpio_to_rdev:
 	pin->request_count++;
 	rdev->ena_pin = pin;
+
+	mutex_unlock(&regulator_list_mutex);
+	kfree(new_pin);
+
 	return 0;
 }
 
@@ -2283,19 +2306,19 @@ static void regulator_ena_gpio_free(struct regulator_dev *rdev)
 
 	/* Free the GPIO only in case of no use */
 	list_for_each_entry_safe(pin, n, &regulator_ena_gpio_list, list) {
-		if (pin->gpiod == rdev->ena_pin->gpiod) {
-			if (pin->request_count <= 1) {
-				pin->request_count = 0;
-				gpiod_put(pin->gpiod);
-				list_del(&pin->list);
-				kfree(pin);
-				rdev->ena_pin = NULL;
-				return;
-			} else {
-				pin->request_count--;
-			}
-		}
+		if (pin != rdev->ena_pin)
+			continue;
+
+		if (--pin->request_count)
+			break;
+
+		gpiod_put(pin->gpiod);
+		list_del(&pin->list);
+		kfree(pin);
+		break;
 	}
+
+	rdev->ena_pin = NULL;
 }
 
 /**
@@ -5059,7 +5082,10 @@ static int regulator_init_coupling(struct regulator_dev *rdev)
 	if (!of_check_coupling_data(rdev))
 		return -EPERM;
 
+	mutex_lock(&regulator_list_mutex);
 	rdev->coupling_desc.coupler = regulator_find_coupler(rdev);
+	mutex_unlock(&regulator_list_mutex);
+
 	if (IS_ERR(rdev->coupling_desc.coupler)) {
 		err = PTR_ERR(rdev->coupling_desc.coupler);
 		rdev_err(rdev, "failed to get coupler: %d\n", err);
@@ -5160,16 +5186,16 @@ regulator_register(const struct regulator_desc *regulator_desc,
 		ret = -ENOMEM;
 		goto rinse;
 	}
+	device_initialize(&rdev->dev);
 
 	/*
 	 * Duplicate the config so the driver could override it after
 	 * parsing init data.
 	 */
 	config = kmemdup(cfg, sizeof(*cfg), GFP_KERNEL);
 	if (config == NULL) {
-		kfree(rdev);
 		ret = -ENOMEM;
-		goto rinse;
+		goto clean;
 	}
 
 	init_data = regulator_of_get_init_data(dev, regulator_desc, config,
@@ -5181,10 +5207,8 @@ regulator_register(const struct regulator_desc *regulator_desc,
 	 * from a gpio extender or something else.
 	 */
 	if (PTR_ERR(init_data) == -EPROBE_DEFER) {
-		kfree(config);
-		kfree(rdev);
 		ret = -EPROBE_DEFER;
-		goto rinse;
+		goto clean;
 	}
 
 	/*
@@ -5225,9 +5249,7 @@ regulator_register(const struct regulator_desc *regulator_desc,
 	}
 
 	if (config->ena_gpiod) {
-		mutex_lock(&regulator_list_mutex);
 		ret = regulator_ena_gpio_request(rdev, config);
-		mutex_unlock(&regulator_list_mutex);
 		if (ret != 0) {
 			rdev_err(rdev, "Failed to request enable GPIO: %d\n",
 				 ret);
@@ -5239,7 +5261,6 @@ regulator_register(const struct regulator_desc *regulator_desc,
 	}
 
 	/* register with sysfs */
-	device_initialize(&rdev->dev);
 	rdev->dev.class = &regulator_class;
 	rdev->dev.parent = dev;
 	dev_set_name(&rdev->dev, "regulator.%lu",
@@ -5267,27 +5288,22 @@ regulator_register(const struct regulator_desc *regulator_desc,
 	if (ret < 0)
 		goto wash;
 
-	mutex_lock(&regulator_list_mutex);
 	ret = regulator_init_coupling(rdev);
-	mutex_unlock(&regulator_list_mutex);
 	if (ret < 0)
 		goto wash;
 
 	/* add consumers devices */
 	if (init_data) {
-		mutex_lock(&regulator_list_mutex);
 		for (i = 0; i < init_data->num_consumer_supplies; i++) {
 			ret = set_consumer_device_supply(rdev,
 				init_data->consumer_supplies[i].dev_name,
 				init_data->consumer_supplies[i].supply);
 			if (ret < 0) {
-				mutex_unlock(&regulator_list_mutex);
 				dev_err(dev, "Failed to set supply %s\n",
 					init_data->consumer_supplies[i].supply);
 				goto unset_supplies;
 			}
 		}
-		mutex_unlock(&regulator_list_mutex);
 	}
 
 	if (!rdev->desc->ops->get_voltage &&
@@ -5322,13 +5338,11 @@ regulator_register(const struct regulator_desc *regulator_desc,
 	mutex_lock(&regulator_list_mutex);
 	regulator_ena_gpio_free(rdev);
 	mutex_unlock(&regulator_list_mutex);
-	put_device(&rdev->dev);
-	rdev = NULL;
 clean:
 	if (dangling_of_gpiod)
 		gpiod_put(config->ena_gpiod);
-	kfree(rdev);
 	kfree(config);
+	put_device(&rdev->dev);
 rinse:
 	if (dangling_cfg_gpiod)
 		gpiod_put(cfg->ena_gpiod);