linux-kernel - Re: [PATCH] sched/core: Remove the unused schedule

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Message-ID: <20190729083039.kwamco7q6glsoo6e@e107158-lin.cambridge.arm.com>
Date:   Mon, 29 Jul 2019 09:30:39 +0100
From:   Qais Yousef <qais.yousef@....com>
To:     Eiichi Tsukata <devel@...ukata.com>
Cc:     tglx@...utronix.de, luto@...nel.org, mingo@...hat.com,
        peterz@...radead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched/core: Remove the unused schedule_user() function

On 07/28/19 01:55, Eiichi Tsukata wrote:
> Since commit 02bc7768fe44 ("x86/asm/entry/64: Migrate error and IRQ exit
> work to C and remove old assembly code"), it's no longer used.

It seems to me that powerpc and sparc are still using it?

$ git grep SCHEDULE_USER
arch/powerpc/include/asm/context_tracking.h:#define SCHEDULE_USER bl    schedule_user
arch/powerpc/include/asm/context_tracking.h:#define SCHEDULE_USER bl    schedule
arch/powerpc/kernel/entry_64.S: SCHEDULE_USER
arch/sparc/kernel/rtrap_64.S:# define SCHEDULE_USER schedule_user
arch/sparc/kernel/rtrap_64.S:# define SCHEDULE_USER schedule
arch/sparc/kernel/rtrap_64.S:           call                    SCHEDULE_USER

Cheers

--
Qais Yousef

> 
> Signed-off-by: Eiichi Tsukata <devel@...ukata.com>
> ---
>  kernel/sched/core.c | 19 -------------------
>  1 file changed, 19 deletions(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 2b037f195473..0079bebe0086 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3973,25 +3973,6 @@ void __sched schedule_idle(void)
>  	} while (need_resched());
>  }
>  
> -#ifdef CONFIG_CONTEXT_TRACKING
> -asmlinkage __visible void __sched schedule_user(void)
> -{
> -	/*
> -	 * If we come here after a random call to set_need_resched(),
> -	 * or we have been woken up remotely but the IPI has not yet arrived,
> -	 * we haven't yet exited the RCU idle mode. Do it here manually until
> -	 * we find a better solution.
> -	 *
> -	 * NB: There are buggy callers of this function.  Ideally we
> -	 * should warn if prev_state != CONTEXT_USER, but that will trigger
> -	 * too frequently to make sense yet.
> -	 */
> -	enum ctx_state prev_state = exception_enter();
> -	schedule();
> -	exception_exit(prev_state);
> -}
> -#endif
> -
>  /**
>   * schedule_preempt_disabled - called with preemption disabled
>   *
> -- 
> 2.21.0
>