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: Jean Delvare <khali@linux-fr.org>
Cc: Michael Lawnick <ml.lawnick@gmx.de>

1 files changed, 7 insertions, 6 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index ba86af63f5cf..97f96b66653c 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -662,9 +662,9 @@ i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
                 return -EINVAL;
 
         /* Keep track of the added device */
-        i2c_lock_adapter(adap);
+        mutex_lock(&adap->userspace_clients_lock);
         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",
                  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 */
         res = -ENOENT;
-        i2c_lock_adapter(adap);
+        mutex_lock(&adap->userspace_clients_lock);
         list_for_each_entry_safe(client, next, &adap->userspace_clients,
                                  detected) {
                 if (client->addr == addr) {
@@ -716,7 +716,7 @@ i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
                         break;
                 }
         }
-        i2c_unlock_adapter(adap);
+        mutex_unlock(&adap->userspace_clients_lock);
 
         if (res < 0)
                 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);
+        mutex_init(&adap->userspace_clients_lock);
         INIT_LIST_HEAD(&adap->userspace_clients);
 
         /* Set default timeout to 1 second if not already set */
@@ -1003,7 +1004,7 @@ int i2c_del_adapter(struct i2c_adapter *adap)
                 return res;
 
         /* 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,
                                  detected) {
                 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);
                 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
            checking the returned value. */