Re: [PATCH RFC] sched/headers: Fix sched_setattr userspace compilation issues

[Joel Fernandes <joel@joelfernandes.org>]

On Thu, May 21, 2020 at 11:53 AM Joel Fernandes (Google)
<joel@joelfernandes.org> wrote:
>
> On a modern Linux distro, compiling the following program fails:
>  #include<stdlib.h>
>  #include<stdint.h>
>  #include<pthread.h>
>  #include<linux/sched/types.h>
>
>  void main() {
>          struct sched_attr sa;
>
>          return;
>  }
>
> with:
> /usr/include/linux/sched/types.h:8:8: \
>                         error: redefinition of ‘struct sched_param’
>     8 | struct sched_param {
>       |        ^~~~~~~~~~~
> In file included from /usr/include/x86_64-linux-gnu/bits/sched.h:74,
>                  from /usr/include/sched.h:43,
>                  from /usr/include/pthread.h:23,
>                  from /tmp/s.c:4:
> /usr/include/x86_64-linux-gnu/bits/types/struct_sched_param.h:23:8:
> note: originally defined here
>    23 | struct sched_param
>       |        ^~~~~~~~~~~
>
> This is also causing a problem on using sched_attr Chrome. The issue is
> sched_param is already provided by glibc.
>
> Guard the kernel's UAPI definition of sched_param with __KERNEL__ so
> that userspace can compile.
>
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>

If it is more preferable, another option is to move sched_param to
include/linux/sched/types.h

 - Joel


> ---
>  include/uapi/linux/sched/types.h | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/include/uapi/linux/sched/types.h b/include/uapi/linux/sched/types.h
> index c852153ddb0d3..1f10d935a63fe 100644
> --- a/include/uapi/linux/sched/types.h
> +++ b/include/uapi/linux/sched/types.h
> @@ -4,9 +4,11 @@
>
>  #include <linux/types.h>
>
> +#if defined(__KERNEL__)
>  struct sched_param {
>         int sched_priority;
>  };
> +#endif
>
>  #define SCHED_ATTR_SIZE_VER0   48      /* sizeof first published struct */
>  #define SCHED_ATTR_SIZE_VER1   56      /* add: util_{min,max} */
> --
> 2.26.2.761.g0e0b3e54be-goog
>