Re: [PATCH v8 12/19] sched: Introduce task_cpus_dl_admissible() to check proposed affinity

Daniel Bristot de Oliveira
2021-06-03T09:45:06Z

On 6/2/21 6:47 PM, Will Deacon wrote:
> In preparation for restricting the affinity of a task during execve()
> on arm64, introduce a new task_cpus_dl_admissible() helper function to
> give an indication as to whether the restricted mask is admissible for
> a deadline task.
>
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
> include/linux/sched.h | 6 ++++++
> kernel/sched/core.c | 44 +++++++++++++++++++++++++++----------------
> 2 files changed, 34 insertions(+), 16 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 91a6cfeae242..9b17d8cfa6ef 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1691,6 +1691,7 @@ extern void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new
> extern int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask);
> extern int dup_user_cpus_ptr(struct task_struct *dst, struct task_struct *src, int node);
> extern void release_user_cpus_ptr(struct task_struct *p);
> +extern bool task_cpus_dl_admissible(struct task_struct *p, const struct cpumask *mask);
> extern void force_compatible_cpus_allowed_ptr(struct task_struct *p);
> extern void relax_compatible_cpus_allowed_ptr(struct task_struct *p);
> #else
> @@ -1713,6 +1714,11 @@ static inline void release_user_cpus_ptr(struct task_struct *p)
> {
> WARN_ON(p->user_cpus_ptr);
> }
> +
> +static inline bool task_cpus_dl_admissible(struct task_struct *p, const struct cpumask *mask)
> +{
> + return true;
> +}
> #endif
>
> extern int yield_to(struct task_struct *p, bool preempt);
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 58e2cf7520c0..b4f8dc18ae11 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -6933,6 +6933,31 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
> return retval;
> }
>
> +#ifdef CONFIG_SMP
> +bool task_cpus_dl_admissible(struct task_struct *p, const struct cpumask *mask)

Would you mind renaming it to dl_task_check_affinity(), in the case of a v9? It
will look coherent with dl_task_can_attach()...

Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>

Thanks!
-- Daniel