Date:   Fri, 14 Jan 2022 11:11:08 +0100
From:   Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To:     Valentin Schneider <valentin.schneider@arm.com>
Cc:     linux-kernel@vger.kernel.org,
        Abhijeet Dharmapurikar <adharmap@quicinc.com>,
        Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Juri Lelli <juri.lelli@redhat.com>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC PATCH 2/2] sched/tracing: Add TASK_RTLOCK_WAIT to
 TASK_REPORT
Message-ID: <YeFMPNnCpiw9fs7e@linutronix.de>
References: <20211129123601.2101873-1-valentin.schneider@arm.com>
 <20211129123601.2101873-3-valentin.schneider@arm.com>
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On 2021-11-29 12:36:01 [+0000], Valentin Schneider wrote:
> TASK_RTLOCK_WAIT currently isn't part of TASK_REPORT, thus a task blocking
> on an rtlock will appear as having a task state == 0, IOW TASK_RUNNING.
> 
> The actual state is saved in p->saved_state, but reading it after reading
> p->__state has a few issues:
> o that could still be TASK_RUNNING in the case of e.g. rt_spin_lock
> o ttwu_state_match() might have changed that to TASK_RUNNING
> 
> Add TASK_RTLOCK_WAIT to TASK_REPORT.
> 
> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>

We used to have the D state which was used in the locked case and was
sufficient. With the rework to TASK_RTLOCK_WAIT (which made other things
easier) we lost that. It makes debuging/ looking into the system more
obvious or does not hide things so why not.

Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

Sebastian