linux-kernel - Re: [PATCH v11 10/14] module: kallsyms: Fix suspicious rcu usage

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Message-ID: <20220628162122.v7s3z24icwavur6y@ava.usersys.com>
Date:   Tue, 28 Jun 2022 17:21:22 +0100
From:   Aaron Tomlin <atomlin@...hat.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     mcgrof@...nel.org, christophe.leroy@...roup.eu, cl@...ux.com,
        mbenes@...e.cz, akpm@...ux-foundation.org, jeyu@...nel.org,
        linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org,
        void@...ifault.com, atomlin@...mlin.com, allen.lkml@...il.com,
        joe@...ches.com, msuchanek@...e.de, oleksandr@...alenko.name,
        jason.wessel@...driver.com, pmladek@...e.com, neelx@...hat.com,
        daniel.thompson@...aro.org, hch@...radead.org,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-rt-users <linux-rt-users@...r.kernel.org>
Subject: Re: [PATCH v11 10/14] module: kallsyms: Fix suspicious rcu usage

On Mon 2022-06-27 23:56 -0400, Steven Rostedt wrote:
> > +	preempt_enable();
> 
>         ^^^^^^^^^^^^^^^^^
> 
> This just introduced an unbounded latency and will fail PREEMPT_RT.
> 

Hi Steve,

Sorry about that!

If I understand correctly, there is absolutely no need to explicitly
disable preemption in this context. I will use: rcu_read_lock() and
rcu_read_unlock(), respectively, which will then be suitable for the
preemptible RCU implementation.


Kind regards,

-- 
Aaron Tomlin