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From:   John Ogness <john.ogness@linutronix.de>
To:     Marco Elver <elver@google.com>, elver@google.com,
        Petr Mladek <pmladek@suse.com>
Cc:     Sergey Senozhatsky <senozhatsky@chromium.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
        Thomas Gleixner <tglx@linutronix.de>,
        Johannes Berg <johannes.berg@intel.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Naresh Kamboju <naresh.kamboju@linaro.org>,
        Linux Kernel Functional Testing <lkft@linaro.org>
Subject: Re: [PATCH -printk] printk, tracing: fix console tracepoint
In-Reply-To: <20220503073844.4148944-1-elver@google.com>
References: <20220503073844.4148944-1-elver@google.com>
Date:   Tue, 03 May 2022 21:20:44 +0206
Message-ID: <87r15ae8d7.fsf@jogness.linutronix.de>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On 2022-05-03, Marco Elver <elver@google.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@linutronix.de>

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

John

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