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[v2,1/1] linux/container_of.h: Warn about loss of constness

Message ID 20221024111627.75183-1-sakari.ailus@linux.intel.com
State New
Headers
Series [v2,1/1] linux/container_of.h: Warn about loss of constness |

Commit Message

Sakari Ailus Oct. 24, 2022, 11:16 a.m. UTC 
  container_of() casts the original type to another which leads to the loss
of the const qualifier if it is not specified in the caller-provided type.
This easily leads to container_of() returning a non-const pointer to a
const struct which the C compiler does not warn about.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 include/linux/container_of.h | 1 +
 1 file changed, 1 insertion(+)

Comments

Andy Shevchenko Oct. 24, 2022, 1:22 p.m. UTC | #1 
On Mon, Oct 24, 2022 at 02:16:27PM +0300, Sakari Ailus wrote:
> container_of() casts the original type to another which leads to the loss
> of the const qualifier if it is not specified in the caller-provided type.
> This easily leads to container_of() returning a non-const pointer to a
> const struct which the C compiler does not warn about.

Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  include/linux/container_of.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/include/linux/container_of.h b/include/linux/container_of.h
> index 2f4944b791b81..591db643269aa 100644
> --- a/include/linux/container_of.h
> +++ b/include/linux/container_of.h
> @@ -13,6 +13,7 @@
>   * @type:	the type of the container struct this is embedded in.
>   * @member:	the name of the member within the struct.
>   *
> + * WARNING: any const qualifier of @ptr is lost.
>   */
>  #define container_of(ptr, type, member) ({				\
>  	void *__mptr = (void *)(ptr);					\
> -- 
> 2.30.2
>
diff mbox series

Patch

diff --git a/include/linux/container_of.h b/include/linux/container_of.h
index 2f4944b791b81..591db643269aa 100644
--- a/include/linux/container_of.h
+++ b/include/linux/container_of.h
@@ -13,6 +13,7 @@ 
  * @type:	the type of the container struct this is embedded in.
  * @member:	the name of the member within the struct.
  *
+ * WARNING: any const qualifier of @ptr is lost.
  */
 #define container_of(ptr, type, member) ({				\
 	void *__mptr = (void *)(ptr);					\