Re: [PATCH RT 2/8] sched: __set_cpus_allowed_ptr: Check cpus_mask, not cpus_ptr

[Sebastian Andrzej Siewior]

On 2019-07-27 00:56:32 [-0500], Scott Wood wrote:
> This function is concerned with the long-term cpu mask, not the
> transitory mask the task might have while migrate disabled.  Before
> this patch, if a task was migrate disabled at the time
> __set_cpus_allowed_ptr() was called, and the new mask happened to be
> equal to the cpu that the task was running on, then the mask update
> would be lost.

lost as in "would not be carried out" I assume.

> Signed-off-by: Scott Wood <swood@xxxxxxxxxx>
> ---
>  kernel/sched/core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index c3407707e367..6e643d656d71 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1218,7 +1218,7 @@ static int __set_cpus_allowed_ptr(struct task_struct *p,
>  		goto out;
>  	}
>  
> -	if (cpumask_equal(p->cpus_ptr, new_mask))
> +	if (cpumask_equal(&p->cpus_mask, new_mask))
>  		goto out;
>  
>  	if (!cpumask_intersects(new_mask, cpu_valid_mask)) {


Sebastian