linux-kernel - Re: [PATCH 3/3] rtmutex: remove unnecessary adjust prio

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Message-ID: <c0985762-1b38-a0e5-9f57-4968f9435d1d@linaro.org>
Date:   Tue, 20 Jun 2017 08:40:13 +0800
From:   Alex Shi <alex.shi@...aro.org>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        "open list:LOCKING PRIMITIVES" <linux-kernel@...r.kernel.org>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Sebastian Siewior <bigeasy@...utronix.de>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Juri Lelli <juri.lelli@....com>,
        Thomas Gleixner <tglx@...utronix.de>, fengguang.wu@...el.com
Subject: Re: [PATCH 3/3] rtmutex: remove unnecessary adjust prio

CC fengguang.

This patch survived in Fengguang's 0day testing on
https://github.com/alexshi/power-scheduling.git rtmutex-doc :)

Regards
Alex

On 05/25/2017 01:26 PM, Alex Shi wrote:
> We don't need to adjust prio before new pi_waiter adding. The prio
> only need update after pi_waiter change or task priority change.
> 
> Signed-off-by: Alex Shi <alex.shi@...aro.org>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Sebastian Siewior <bigeasy@...utronix.de>
> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
> Cc: Juri Lelli <juri.lelli@....com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> To: linux-kernel@...r.kernel.org
> To: Ingo Molnar <mingo@...hat.com>
> To: Peter Zijlstra <peterz@...radead.org>
> ---
>  kernel/locking/rtmutex.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
> index b955094..b659ba0 100644
> --- a/kernel/locking/rtmutex.c
> +++ b/kernel/locking/rtmutex.c
> @@ -963,7 +963,6 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
>  		return -EDEADLK;
>  
>  	raw_spin_lock(&task->pi_lock);
> -	rt_mutex_adjust_prio(task);
>  	waiter->task = task;
>  	waiter->lock = lock;
>  	waiter->prio = task->prio;
>