[PATCH] i2c: Prevent deadlock on i2c client registration

Delay the call to adapter->client_register() until after we are
certain that the client registration is a success. At this point the
client is fully initialized and we no longer hold the adapter->clist
mutex, so this should prevent the deadlocks if the client_register()
callback needs to take that mutex too, as is the case for the bttv
driver.

This fixes bug #7234.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 13 insertions, 12 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 01233f0f7771..7ca81f42d14b 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -420,14 +420,6 @@ int i2c_attach_client(struct i2c_client *client)
         }
         list_add_tail(&client->list,&adapter->clients);
         
-        if (adapter->client_register)  {
-                if (adapter->client_register(client))  {
-                        dev_dbg(&adapter->dev, "client_register "
-                                "failed for client [%s] at 0x%02x\n",
-                                client->name, client->addr);
-                }
-        }
-
         client->usage_count = 0;
 
         client->dev.parent = &client->adapter->dev;
@@ -445,10 +437,17 @@ int i2c_attach_client(struct i2c_client *client)
         res = device_create_file(&client->dev, &dev_attr_client_name);
         if (res)
                 goto out_unregister;
-
-out_unlock:
         mutex_unlock(&adapter->clist_lock);
-        return res;
+
+        if (adapter->client_register)  {
+                if (adapter->client_register(client)) {
+                        dev_dbg(&adapter->dev, "client_register "
+                                "failed for client [%s] at 0x%02x\n",
+                                client->name, client->addr);
+                }
+        }
+
+        return 0;
 
 out_unregister:
         init_completion(&client->released); /* Needed? */
@@ -458,7 +457,9 @@ out_list:
         list_del(&client->list);
         dev_err(&adapter->dev, "Failed to attach i2c client %s at 0x%02x "
                 "(%d)\n", client->name, client->addr, res);
-        goto out_unlock;
+out_unlock:
+        mutex_unlock(&adapter->clist_lock);
+        return res;
 }