Re: [PATCH] sched: unlikely corrupted stack end

Ingo Molnar
2016-06-14T07:43:51Z

* WANG Chao <wcwxyz@gmail.com> wrote:

> unlikely() was dropped in commit ce03e41 ("sched/core: Drop unlikely
> behind BUG_ON()"), but commit 29d6455 ("sched: panic on corrupted stack
> end") dropped BUG_ON() and called panic directly.
>
> Now we should bring unlikely() back for branch prediction.
>
> Signed-off-by: WANG Chao <wcwxyz@gmail.com>
> ---
> 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 017d539..7db442c 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3170,7 +3170,7 @@ static noinline void __schedule_bug(struct task_struct *prev)
> static inline void schedule_debug(struct task_struct *prev)
> {
> #ifdef CONFIG_SCHED_STACK_END_CHECK
> - if (task_stack_end_corrupted(prev))
> + if (unlikely(task_stack_end_corrupted(prev)))
> panic("corrupted stack end detected inside scheduler\n");
> #endif

It would be better and cleaner to push that into the task_stack_end_corrupted()
definition. (and to turn it into an inline function while we are touching it.)

Thanks,

Ingo