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authorCornelia Huck <cornelia.huck@de.ibm.com>2008-09-03 18:26:40 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2008-10-16 09:24:48 -0700
commit5739411acbaa63a6c22c91e340fdcdbcc7d82a51 (patch)
tree1f54912f36211076a341067395599ec449bc1ae5 /drivers
parent9cf899d12583082c77a0fcc758f3179b440518ee (diff)
Driver core: Clarify device cleanup.
Make the comments on how to use device_initialize(), device_add() and device_register() a bit clearer - in particular, explicitly note that put_device() must be used once we tried to add the device to the hierarchy. Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/base/core.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/drivers/base/core.c b/drivers/base/core.c
index b98cb1416a2d..aac91e89d6af 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -523,11 +523,16 @@ static void klist_children_put(struct klist_node *n)
* device_initialize - init device structure.
* @dev: device.
*
- * This prepares the device for use by other layers,
- * including adding it to the device hierarchy.
+ * This prepares the device for use by other layers by initializing
+ * its fields.
* It is the first half of device_register(), if called by
- * that, though it can also be called separately, so one
- * may use @dev's fields (e.g. the refcount).
+ * that function, though it can also be called separately, so one
+ * may use @dev's fields. In particular, get_device()/put_device()
+ * may be used for reference counting of @dev after calling this
+ * function.
+ *
+ * NOTE: Use put_device() to give up your reference instead of freeing
+ * @dev directly once you have called this function.
*/
void device_initialize(struct device *dev)
{
@@ -835,9 +840,13 @@ static void device_remove_sys_dev_entry(struct device *dev)
* This is part 2 of device_register(), though may be called
* separately _iff_ device_initialize() has been called separately.
*
- * This adds it to the kobject hierarchy via kobject_add(), adds it
+ * This adds @dev to the kobject hierarchy via kobject_add(), adds it
* to the global and sibling lists for the device, then
* adds it to the other relevant subsystems of the driver model.
+ *
+ * NOTE: _Never_ directly free @dev after calling this function, even
+ * if it returned an error! Always use put_device() to give up your
+ * reference instead.
*/
int device_add(struct device *dev)
{
@@ -965,6 +974,10 @@ done:
* I.e. you should only call the two helpers separately if
* have a clearly defined need to use and refcount the device
* before it is added to the hierarchy.
+ *
+ * NOTE: _Never_ directly free @dev after calling this function, even
+ * if it returned an error! Always use put_device() to give up the
+ * reference initialized in this function instead.
*/
int device_register(struct device *dev)
{