linux-kernel - Re: [PATCH -printk] printk, tracing: fix console tracepoint

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87r15ae8d7.fsf@jogness.linutronix.de>
Date:   Tue, 03 May 2022 21:20:44 +0206
From:   John Ogness <john.ogness@...utronix.de>
To:     Marco Elver <elver@...gle.com>, elver@...gle.com,
        Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com,
        Thomas Gleixner <tglx@...utronix.de>,
        Johannes Berg <johannes.berg@...el.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Naresh Kamboju <naresh.kamboju@...aro.org>,
        Linux Kernel Functional Testing <lkft@...aro.org>
Subject: Re: [PATCH -printk] printk, tracing: fix console tracepoint

On 2022-05-03, Marco Elver <elver@...gle.com> wrote:
> One notable difference is that by moving tracing into printk_sprint(),
> the 'text' will no longer include the "header" (loglevel and timestamp),
> but only the raw message. Arguably this is less of a problem now that
> the console tracepoint happens on the printk() call and isn't delayed.

Another slight difference is that messages composed of LOG_CONT pieces
will trigger the tracepoint for each individual piece and _never_ as a
complete line.

It was never guaranteed that all LOG_CONT pieces make it into the final
printed line anyway, but with this change it will be guaranteed that
they are always handled separately.

I am OK with this change, but like Steven, I agree the the users of that
tracepoint need to chime in.

Acked-by: John Ogness <john.ogness@...utronix.de>

The ongoing printbuf/seq_buf work [0] will hopefully someday do away
with LOG_CONT altogether.

John

[0] https://lwn.net/Articles/892611