[PATCH] driver core: Clarify which counterparts to use to device_add()

[PATCH] driver core: Clarify which counterparts to use to device_add()

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

It is not absolutely clear from the docs how the cleanup path after
device_add() should look like so spell it out explicitly.

No functional changes, just documentation.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
---
 drivers/base/core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 4aeaa0c92bda..fd7511e04e62 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1999,6 +1999,11 @@ static int device_private_init(struct device *dev)
  * 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.
+ *
+ * Rule of thumb is: if device_add() succeeds, you should call
+ * device_del() when you want to get rid of it. If device_add() has
+ * *not* succeeded, use *only* put_device() to drop the reference
+ * count.
  */
 int device_add(struct device *dev)
 {
-- 
2.21.0

Re: [PATCH] driver core: Clarify which counterparts to use to device_add()

[Rafael J. Wysocki]

On Thu, Apr 18, 2019 at 7:42 PM Borislav Petkov <bp@alien8.de> wrote:
>
> From: Borislav Petkov <bp@suse.de>
>
> It is not absolutely clear from the docs how the cleanup path after
> device_add() should look like so spell it out explicitly.
>
> No functional changes, just documentation.
>
> Signed-off-by: Borislav Petkov <bp@suse.de>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
>  drivers/base/core.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 4aeaa0c92bda..fd7511e04e62 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -1999,6 +1999,11 @@ static int device_private_init(struct device *dev)
>   * 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.
> + *
> + * Rule of thumb is: if device_add() succeeds, you should call
> + * device_del() when you want to get rid of it. If device_add() has
> + * *not* succeeded, use *only* put_device() to drop the reference
> + * count.
>   */
>  int device_add(struct device *dev)
>  {
> --
> 2.21.0
>