Re: [PATCH] wireless: Use linux/stddef.h instead of stddef.h

["Jérôme Pouiller" <jerome.pouiller@silabs.com>]

On Thursday 21 May 2020 22:14:22 CEST Hauke Mehrtens wrote:
> When compiling inside the kernel include linux/stddef.h instead of
> stddef.h. When I compile this header file in backports for power PC I
> run into a conflict with ptrdiff_t. I was unable to reproduce this in
> mainline kernel. I still would like to fix this problem in the kernel.
>
> Fixes: 6989310f5d43 ("wireless: Use offsetof instead of custom macro.")
> Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
> ---
>  include/uapi/linux/wireless.h | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/include/uapi/linux/wireless.h b/include/uapi/linux/wireless.h
> index a2c006a364e0..24f3371ad826 100644
> --- a/include/uapi/linux/wireless.h
> +++ b/include/uapi/linux/wireless.h
> @@ -74,7 +74,11 @@
>  #include <linux/socket.h>              /* for "struct sockaddr" et al  */
>  #include <linux/if.h>                  /* for IFNAMSIZ and co... */
> 
> -#include <stddef.h>                     /* for offsetof */
> +#ifdef __KERNEL__
> +#      include <linux/stddef.h>        /* for offsetof */
> +#else
> +#      include <stddef.h>              /* for offsetof */
> +#endif

Hello,

This patch also solves a warning I encountered when I launched sparse
(with make C=1):

  /usr/lib/gcc-cross/arm-linux-gnueabihf/9/include/stddef.h:406:9: warning: preprocessor token offsetof redefined
  ./include/linux/stddef.h:17:9: this was the original definition

However, I wonder if it useful to keep 'include <stddef.h>' when this file
is included from userspace. If it does not compile anymore, there is
problem somewhere else, no?

(Globally, I always find suspicious a kernel source that includes a system
header)


-- 
Jérôme Pouiller