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From:   John Ogness <john.ogness@linutronix.de>
To:     Petr Mladek <pmladek@suse.com>,
        Doug Anderson <dianders@chromium.org>
Cc:     Sergey Senozhatsky <senozhatsky@chromium.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        LKML <linux-kernel@vger.kernel.org>,
        Jason Wessel <jason.wessel@windriver.com>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Aaron Tomlin <atomlin@redhat.com>,
        Luis Chamberlain <mcgrof@kernel.org>,
        kgdb-bugreport@lists.sourceforge.net, linux-serial@vger.kernel.org
Subject: Re: [PATCH printk 10/18] kgbd: Pretend that console list walk is safe
In-Reply-To: <YzarXlj1NyFGTC08@alley>
References: <20220924000454.3319186-1-john.ogness@linutronix.de>
 <20220924000454.3319186-11-john.ogness@linutronix.de>
 <CAD=FV=U3m_mVLpWna3pgi4=b7OCzUxmKh666g62zPNaB+6QHUA@mail.gmail.com>
 <YzarXlj1NyFGTC08@alley>
Date:   Fri, 30 Sep 2022 15:50:56 +0206
Message-ID: <87o7uxugbr.fsf@jogness.linutronix.de>
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On 2022-09-30, Petr Mladek <pmladek@suse.com> wrote:
> Anyway, what about using the later added SRCU walk here?
> After all, this is exactly what RCU is for, isn't it?

So I think a lot of the problems with this series is that SRCU is
introduced too late. We are debating things in patch 6 that are
irrelevant by patch 12.

I will rework the series so that the changes come in the following
order:

1. provide an atomic console_is_enabled()

2. convert the list to SRCU

3. move all iterators from console_lock()/console_trylock() to SRCU

Step 3 may result in console_lock()/console_trylock() calls disappearing
or relocating to where they are needed for non-list-synchronization
purposes.

John