Re: [PATCH 2/2] sched/deadline: Don't return invalid cpu in cpudl_maximum_cpu()

[Juri Lelli]

Hi,

On 02/06/17 16:31, Byungchul Park wrote:
> When the heap tree is empty, cp->elements[0].cpu has meaningless value.
> We need to consider the case.
> 
> Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
> ---
>  kernel/sched/cpudeadline.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
> index d4a6963..9b314a9 100644
> --- a/kernel/sched/cpudeadline.c
> +++ b/kernel/sched/cpudeadline.c
> @@ -110,7 +110,8 @@ static void cpudl_heapify(struct cpudl *cp, int idx)
>  
>  static inline int cpudl_maximum_cpu(struct cpudl *cp)
>  {
> -	return cp->elements[0].cpu;
> +	int cpu = cp->elements[0].cpu;
> +	return cp->elements[cpu].idx == IDX_INVALID ? -1 : cpu;

Mmm, don't we get a WARN from cpumask_check() if we return -1 here?

Thanks,

- Juri