On Tue, 27 Oct 2020 01:41:52 +0800
Hui Su <[email protected]> wrote:
> Use the list_is_singular(&rt_se->run_list) api instead of
> 'rt_se->run_list.prev != rt_se->run_list.next'.
> Fix a comment by the way, and make the comment more clearly.
>
> Signed-off-by: Hui Su <[email protected]>
> ---
> kernel/sched/rt.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 49ec096a8aa1..1479d00656b4 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -2381,7 +2381,7 @@ static inline void watchdog(struct rq *rq, struct
> task_struct *p) { }
> *
> * NOTE: This function can be called remotely by the tick offload that
> * goes along full dynticks. Therefore no local assumption can be made
> - * and everything must be accessed through the @rq and @curr passed in
> + * and everything must be accessed through the @rq and @p passed in
> * parameters.
> */
> static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
> @@ -2406,11 +2406,11 @@ static void task_tick_rt(struct rq *rq, struct
> task_struct *p, int queued)
> p->rt.time_slice = sched_rr_timeslice;
>
> /*
> - * Requeue to the end of queue if we (and all of our ancestors) are not
> - * the only element on the queue
> + * Requeue to the end of rt_prio_array queue if we (and all of our
> + * ancestors) are not the only element on the rt_prio_array queue.
> */
> for_each_sched_rt_entity(rt_se) {
> - if (rt_se->run_list.prev != rt_se->run_list.next) {
> + if (!list_is_singular(&rt_se->run_list)) {
Perhaps there should be a list_has_more_than_one() API, as list_is_singular
requires two checks, and the "more_than_one" only requires a single check.
list_is_singular() is:
return !list_empty(list) && (list->next == list->prev);
which is more work than what you are replacing.
-- Steve
> requeue_task_rt(rq, p, 0);
> resched_curr(rq);
> return;
