linux-kernel - Re: [PATCH] x86: Avoid pr_cont() in show

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Message-ID: <218baff7-9473-ac1e-2449-13de98fa6dc9@rasmusvillemoes.dk>
Date:   Tue, 17 Jul 2018 16:24:30 +0200
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Ingo Molnar <mingo@...nel.org>
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org,
        Tetsuo Handa <penguin-kernel@...ove.SKAURA.ne.jp>,
        Andy Lutomirski <luto@...capital.net>,
        Borislav Petkov <bp@...e.de>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] x86: Avoid pr_cont() in show_opcodes()

On 2018-07-17 15:53, Tetsuo Handa wrote:
> On 2018/07/17 18:01, Rasmus Villemoes wrote:
>> Why not this instead? Less stack use, less code, no intermediary
>> snprintfs, no pr_cont...
> 
> Excellent! I didn't notice %ph extension.
> 
>> Not compile-tested, probably whitespace-damaged, but you get the idea.
> 
> Yes, it works well.
> 
> 
> 
> From 96d9d4d135994a081e54d33d23f5007c53d9b5dd Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
> Date: Tue, 17 Jul 2018 22:47:11 +0900
> Subject: [PATCH v3] x86: Avoid pr_cont() in show_opcodes()
> 
> Since syzbot is confused by concurrent printk() messages [1],
> this patch changes show_opcodes() to use %*ph format string.
> 
> When we start adding prefix to each line of printk() output,
> we will be able to handle concurrent printk() messages.
> 
> [1] https://syzkaller.appspot.com/text?tag=CrashReport&x=139d342c400000
> 
> Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SKAURA.ne.jp>
> Signed-off-by: Rasmus Villemoes <mail@...musvillemoes.dk>

I'm not sure that SoB-chain is correct. Anyway, however which way, and
if at all, you want to credit me, please use the email address
linux@...musvillemoes.dk . I probably botched From header in the
previous mail, not used to using Thunderbird...

Rasmus