Re: [PATCH v5 01/15] sched/core: uclamp: extend sched_setattr to support utilization clamping

[Peter Zijlstra <peterz@infradead.org>]

On Mon, Oct 29, 2018 at 06:32:55PM +0000, Patrick Bellasi wrote:
> diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h
> index 22627f80063e..c27d6e81517b 100644
> --- a/include/uapi/linux/sched.h
> +++ b/include/uapi/linux/sched.h
> @@ -50,9 +50,11 @@
>  #define SCHED_FLAG_RESET_ON_FORK	0x01
>  #define SCHED_FLAG_RECLAIM		0x02
>  #define SCHED_FLAG_DL_OVERRUN		0x04
> +#define SCHED_FLAG_UTIL_CLAMP		0x08
>  
>  #define SCHED_FLAG_ALL	(SCHED_FLAG_RESET_ON_FORK	| \
>  			 SCHED_FLAG_RECLAIM		| \
> -			 SCHED_FLAG_DL_OVERRUN)
> +			 SCHED_FLAG_DL_OVERRUN		| \
> +			 SCHED_FLAG_UTIL_CLAMP)
>  
>  #endif /* _UAPI_LINUX_SCHED_H */
> diff --git a/include/uapi/linux/sched/types.h b/include/uapi/linux/sched/types.h
> index 10fbb8031930..fde7301ed28c 100644
> --- a/include/uapi/linux/sched/types.h
> +++ b/include/uapi/linux/sched/types.h
> @@ -9,6 +9,7 @@ struct sched_param {
>  };
>  
>  #define SCHED_ATTR_SIZE_VER0	48	/* sizeof first published struct */
> +#define SCHED_ATTR_SIZE_VER1	56	/* add: util_{min,max} */
>  
>  /*
>   * Extended scheduling parameters data structure.


--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4533,6 +4533,10 @@ static int sched_copy_attr(struct sched_
 	if (ret)
 		return -EFAULT;
 
+	if ((attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) &&
+	    size < SCHED_ATTR_SIZE_VER1)
+		return -EINVAL;
+
 	/*
 	 * XXX: Do we want to be lenient like existing syscalls; or do we want
 	 * to be strict and return an error on out-of-bounds values?