* [PATCH v2 1/1] linux/container_of.h: Warn about loss of constness
@ 2022-10-24 11:16 Sakari Ailus
2022-10-24 13:22 ` Andy Shevchenko
0 siblings, 1 reply; 2+ messages in thread
From: Sakari Ailus @ 2022-10-24 11:16 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: linux-kernel, Andy Shevchenko, Rafael J. Wysocki, David Laight
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(+)
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
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: [PATCH v2 1/1] linux/container_of.h: Warn about loss of constness
2022-10-24 11:16 [PATCH v2 1/1] linux/container_of.h: Warn about loss of constness Sakari Ailus
@ 2022-10-24 13:22 ` Andy Shevchenko
0 siblings, 0 replies; 2+ messages in thread
From: Andy Shevchenko @ 2022-10-24 13:22 UTC (permalink / raw)
To: Sakari Ailus
Cc: Greg Kroah-Hartman, linux-kernel, Rafael J. Wysocki, David Laight
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
>
--
With Best Regards,
Andy Shevchenko
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2022-10-24 11:16 [PATCH v2 1/1] linux/container_of.h: Warn about loss of constness Sakari Ailus
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