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Commit dafc50d1 authored by Jean Delvare's avatar Jean Delvare
Browse files

i2c: Use a separate mutex for userspace client lists 



Moving userspace-instantiated clients to separate lists wasn't nearly
enough to avoid deadlocks in multiplexed bus cases. We also want to
have a dedicated mutex to protect each list.

Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
Cc: Michael Lawnick <ml.lawnick@gmx.de>
parent 8031d79b

drivers/i2c/i2c-core.c

+7 −6
Original line number Original line Diff line number Diff line
@@ -662,9 +662,9 @@ i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr, 
		return -EINVAL;

		return -EINVAL;





	/* Keep track of the added device */

	/* Keep track of the added device */

	i2c_lock_adapter(adap);

	mutex_lock(&adap->userspace_clients_lock);

	list_add_tail(&client->detected, &adap->userspace_clients);

	list_add_tail(&client->detected, &adap->userspace_clients);

	i2c_unlock_adapter(adap);

	mutex_unlock(&adap->userspace_clients_lock);

	dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",

	dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",

		 info.type, info.addr);

		 info.type, info.addr);
@@ -703,7 +703,7 @@ i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr, 




	/* Make sure the device was added through sysfs */

	/* Make sure the device was added through sysfs */

	res = -ENOENT;

	res = -ENOENT;

	i2c_lock_adapter(adap);

	mutex_lock(&adap->userspace_clients_lock);

	list_for_each_entry_safe(client, next, &adap->userspace_clients,

	list_for_each_entry_safe(client, next, &adap->userspace_clients,

				 detected) {

				 detected) {

		if (client->addr == addr) {

		if (client->addr == addr) {
@@ -716,7 +716,7 @@ i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr, 
			break;

			break;

		}

		}

	}

	}

	i2c_unlock_adapter(adap);

	mutex_unlock(&adap->userspace_clients_lock);





	if (res < 0)

	if (res < 0)

		dev_err(dev, "%s: Can't find device in list\n",

		dev_err(dev, "%s: Can't find device in list\n",
@@ -798,6 +798,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap) 
	}

	}





	rt_mutex_init(&adap->bus_lock);

	rt_mutex_init(&adap->bus_lock);

	mutex_init(&adap->userspace_clients_lock);

	INIT_LIST_HEAD(&adap->userspace_clients);

	INIT_LIST_HEAD(&adap->userspace_clients);





	/* Set default timeout to 1 second if not already set */

	/* Set default timeout to 1 second if not already set */
@@ -1003,7 +1004,7 @@ int i2c_del_adapter(struct i2c_adapter *adap) 
		return res;

		return res;





	/* Remove devices instantiated from sysfs */

	/* Remove devices instantiated from sysfs */

	i2c_lock_adapter(adap);

	mutex_lock(&adap->userspace_clients_lock);

	list_for_each_entry_safe(client, next, &adap->userspace_clients,

	list_for_each_entry_safe(client, next, &adap->userspace_clients,

				 detected) {

				 detected) {

		dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,

		dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
@@ -1011,7 +1012,7 @@ int i2c_del_adapter(struct i2c_adapter *adap) 
		list_del(&client->detected);

		list_del(&client->detected);

		i2c_unregister_device(client);

		i2c_unregister_device(client);

	}

	}

	i2c_unlock_adapter(adap);

	mutex_unlock(&adap->userspace_clients_lock);





	/* Detach any active clients. This can't fail, thus we do not

	/* Detach any active clients. This can't fail, thus we do not

	   checking the returned value. */

	   checking the returned value. */

include/linux/i2c.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -368,6 +368,7 @@ struct i2c_adapter { 
	char name[48];

	char name[48];

	struct completion dev_released;

	struct completion dev_released;





	struct mutex userspace_clients_lock;

	struct list_head userspace_clients;

	struct list_head userspace_clients;

};

};

#define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)

#define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)