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

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Message-ID: <8e7a3e658dbb928477639e0da67a5a204456b065.camel@perches.com>
Date:   Tue, 17 Jul 2018 14:19:48 -0700
From:   Joe Perches <joe@...ches.com>
To:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Ingo Molnar <mingo@...nel.org>
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org,
        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 Wed, 2018-07-18 at 05:54 +0900, Tetsuo Handa wrote:
> Corrected Signed-off-by: addresses.
> 
> 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 v4] 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.

If this were applied via git am, the commit would include
all the content from "Corrected Signed-off-by:"

Perhaps it would be better to send this as a new patch without
the leading 7 lines after the email header

> diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
[]
> @@ -93,26 +93,15 @@ static void printk_stack_address(unsigned long address, int reliable,
>   */
>  void show_opcodes(u8 *rip, const char *loglvl)
>  {
> -	unsigned int code_prologue = OPCODE_BUFSIZE * 2 / 3;
> +	const unsigned int prologue = OPCODE_BUFSIZE * 2 / 3;

And this might be better as a #define to avoid
a few more bytes of stack consumption.