Re: [PATCH 01/14] sched: add sched_class->task_dead.

[Paul Turner <pjt@google.com>]

On Thu, Nov 7, 2013 at 5:43 AM, Juri Lelli <juri.lelli@gmail.com> wrote:
> From: Dario Faggioli <raistlin@linux.it>
>
> Add a new function to the scheduling class interface. It is called
> at the end of a context switch, if the prev task is in TASK_DEAD state.
>
> It might be useful for the scheduling classes that want to be notified
> when one of their task dies, e.g. to perform some cleanup actions.

We could also usefully use this within SCHED_FAIR to remove a task's
load contribution when it completes.

>
> Signed-off-by: Dario Faggioli <raistlin@linux.it>
> Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
> ---
>  kernel/sched/core.c  |    3 +++
>  kernel/sched/sched.h |    1 +
>  2 files changed, 4 insertions(+)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 5ac63c9..850a02c 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1890,6 +1890,9 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev)
>         if (mm)
>                 mmdrop(mm);
>         if (unlikely(prev_state == TASK_DEAD)) {
> +               if (prev->sched_class->task_dead)
> +                       prev->sched_class->task_dead(prev);
> +
>                 /*
>                  * Remove function-return probe instances associated with this
>                  * task and put them back on the free list.
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index b3c5653..64eda5c 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -992,6 +992,7 @@ struct sched_class {
>         void (*set_curr_task) (struct rq *rq);
>         void (*task_tick) (struct rq *rq, struct task_struct *p, int queued);
>         void (*task_fork) (struct task_struct *p);
> +       void (*task_dead) (struct task_struct *p);
>
>         void (*switched_from) (struct rq *this_rq, struct task_struct *task);
>         void (*switched_to) (struct rq *this_rq, struct task_struct *task);

Reviewed-by: Paul Turner <pjt@google.com>

> --
> 1.7.9.5
>
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