linux-kernel - Re: [PATCH] printk: inject caller information into the body of message

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Date:   Mon, 1 Oct 2018 11:58:28 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:     Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitriy Vyukov <dvyukov@...gle.com>,
        kbuild test robot <fengguang.wu@...el.com>,
        syzkaller <syzkaller@...glegroups.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: Re: [PATCH] printk: inject caller information into the body of
 message

On (10/01/18 11:37), Sergey Senozhatsky wrote:
> If we are about to have a list of printk buffers then we probably can
> define a list of NR_CPUS cont buffers. And we probably can reuse the
> existing struct cont for buffered printk, having 2 different struct-s
> for the same thing - struct cont and struct printk_buffer - is not very
> cool.

And we also can re-use cont_add() / cont_flush() / etc.
Just pass a specific struct cont *cont to those functions.

> All printk()-s are limited by LOG_LINE_MAX. Buffered printk() is not
> special.

Correction: I was wrong about this.

Looking at cont handling, it seems that buffered printk is special after
all. We do let it to be over LOG_LINE_MAX:

	if (nr_ext_console_drivers || cont.len + len > sizeof(cont.buf))
		cont_flush();

	-ss