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Commit 6629dcff authored by Jean Delvare's avatar Jean Delvare
Browse files

i2c-core: Use per-adapter userspace device lists 



Using a single list for all userspace devices leads to a dead lock
on multiplexed buses in some circumstances (mux chip instantiated
from userspace). This is solved by using a separate list for each
bus segment.

Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
Acked-by: default avatarMichael Lawnick <ml.lawnick@gmx.de>
parent b1d4b390

drivers/i2c/i2c-core.c

+18 −16
Original line number Diff line number Diff line
@@ -40,12 +40,11 @@ 
#include "i2c-core.h"





/* core_lock protects i2c_adapter_idr, userspace_devices, and guarantees

/* core_lock protects i2c_adapter_idr, and guarantees

   that device detection, deletion of detected devices, and attach_adapter

   and detach_adapter calls are serialized */

static DEFINE_MUTEX(core_lock);

static DEFINE_IDR(i2c_adapter_idr);

static LIST_HEAD(userspace_devices);



static struct device_type i2c_client_type;

static int i2c_check_addr(struct i2c_adapter *adapter, int addr);
@@ -542,9 +541,9 @@ i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr, 
		return -EEXIST;



	/* Keep track of the added device */

	mutex_lock(&core_lock);

	list_add_tail(&client->detected, &userspace_devices);

	mutex_unlock(&core_lock);

	i2c_lock_adapter(adap);

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

	i2c_unlock_adapter(adap);

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

		 info.type, info.addr);
@@ -583,9 +582,10 @@ i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr, 


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

	res = -ENOENT;

	mutex_lock(&core_lock);

	list_for_each_entry_safe(client, next, &userspace_devices, detected) {

		if (client->addr == addr && client->adapter == adap) {

	i2c_lock_adapter(adap);

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

				 detected) {

		if (client->addr == addr) {

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

				 "delete_device", client->name, client->addr);
@@ -595,7 +595,7 @@ i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr, 
			break;

		}

	}

	mutex_unlock(&core_lock);

	i2c_unlock_adapter(adap);



	if (res < 0)

		dev_err(dev, "%s: Can't find device in list\n",
@@ -677,6 +677,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap) 
	}



	rt_mutex_init(&adap->bus_lock);

	INIT_LIST_HEAD(&adap->userspace_clients);



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

	if (adap->timeout == 0)
@@ -879,14 +880,15 @@ int i2c_del_adapter(struct i2c_adapter *adap) 
		return res;



	/* Remove devices instantiated from sysfs */

	list_for_each_entry_safe(client, next, &userspace_devices, detected) {

		if (client->adapter == adap) {

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

				client->name, client->addr);

	i2c_lock_adapter(adap);

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

				 detected) {

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

			client->addr);

		list_del(&client->detected);

		i2c_unregister_device(client);

	}

	}

	i2c_unlock_adapter(adap);



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

	   checking the returned value. */

include/linux/i2c.h

+2 −0
Original line number Diff line number Diff line
@@ -355,6 +355,8 @@ struct i2c_adapter { 
	int nr;

	char name[48];

	struct completion dev_released;



	struct list_head userspace_clients;

};

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