Re: [PATCH] sched/deadline: Use bools for the state flags

[Thomas Gleixner]

On Tue, 21 Nov 2017, Jiri Kosina wrote:

> From: Jiri Kosina <jkosina@xxxxxxx>
> 
> Commit
> 
> 	799ba82de01e ("sched/deadline: Use C bitfields for the state flags")
> 
> converted state flags into one-bit signed int. Signed one-bit type can be 
> either 0 or -1, which is going to cause a problem once 1 is assigned to it 
> and then the value later tested against 1.
> 
> The current code is okay, as all the checks are (non-)zero check, but I 
> believe that we'd rather be safe than sorry here; remove the fragility by 
> converting the state flags to bool.
> 
> This also silences annoying sparse complaints about this very issue when 
> compiling any code that includes sched.h.

What's wrong with making these bitfields 'unsigned int' ?

> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index a5dc7c98b0a2..b19fa1b96726 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -473,10 +473,10 @@ struct sched_dl_entity {
>  	 * conditions between the inactive timer handler and the wakeup
>  	 * code.
>  	 */
> -	int				dl_throttled      : 1;
> -	int				dl_boosted        : 1;
> -	int				dl_yielded        : 1;
> -	int				dl_non_contending : 1;
> +	bool				dl_throttled;
> +	bool				dl_boosted;
> +	bool				dl_yielded;
> +	bool				dl_non_contending;

Thanks,

	tglx