i2c-remove-redundant-i2c_client-list.patch

This goes on top of the patch removing most i2c_adapter.clients usage,
updating i2c_attach_client:

 - Don't call device_register() while holding clist_lock.  This
   removes a self-deadlock when on the i2c_driver.probe() path,
   for drivers that need to attach new devices (e.g. dummies).

 - Remove a redundant address check.  The driver model core does
   this as a consequence of guaranteeing unique names.

 - Move the "device registered" diagnostic so that it never lies;
   previously, on error paths it would falsely report success.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 8 insertions, 14 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index c8bbd672226b..824f12c798d6 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -709,13 +709,6 @@ int i2c_attach_client(struct i2c_client *client)
         struct i2c_adapter *adapter = client->adapter;
         int res = 0;
 
-        mutex_lock(&adapter->clist_lock);
-        if (i2c_check_addr(client->adapter, client->addr)) {
-                res = -EBUSY;
-                goto out_unlock;
-        }
-        list_add_tail(&client->list,&adapter->clients);
-
         client->dev.parent = &client->adapter->dev;
         client->dev.bus = &i2c_bus_type;
 
@@ -730,13 +723,17 @@ int i2c_attach_client(struct i2c_client *client)
 
         snprintf(&client->dev.bus_id[0], sizeof(client->dev.bus_id),
                 "%d-%04x", i2c_adapter_id(adapter), client->addr);
-        dev_dbg(&adapter->dev, "client [%s] registered with bus id %s\n",
-                client->name, client->dev.bus_id);
         res = device_register(&client->dev);
         if (res)
-                goto out_list;
+                goto out_err;
+
+        mutex_lock(&adapter->clist_lock);
+        list_add_tail(&client->list, &adapter->clients);
         mutex_unlock(&adapter->clist_lock);
 
+        dev_dbg(&adapter->dev, "client [%s] registered with bus id %s\n",
+                client->name, client->dev.bus_id);
+
         if (adapter->client_register)  {
                 if (adapter->client_register(client)) {
                         dev_dbg(&adapter->dev, "client_register "
@@ -747,12 +744,9 @@ int i2c_attach_client(struct i2c_client *client)
 
         return 0;
 
-out_list:
-        list_del(&client->list);
+out_err:
         dev_err(&adapter->dev, "Failed to attach i2c client %s at 0x%02x "
                 "(%d)\n", client->name, client->addr, res);
-out_unlock:
-        mutex_unlock(&adapter->clist_lock);
         return res;
 }
 EXPORT_SYMBOL(i2c_attach_client);