linux-kernel - Re: [RFC] printk/sysrq: Don't play with console

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Message-ID: <20190607170922.GA17017@xo-6d-61-c0.localdomain>
Date:   Fri, 7 Jun 2019 19:09:22 +0200
From:   Pavel Machek <pavel@....cz>
To:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Dmitry Safonov <dima@...sta.com>, linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [RFC] printk/sysrq: Don't play with console_loglevel

On Tue 2019-05-28 19:15:43, Tetsuo Handa wrote:
> On 2019/05/28 17:51, Sergey Senozhatsky wrote:
> >> You are trying to omit passing KERN_UNSUPPRESSED by utilizing implicit printk
> >> context information. But doesn't such attempt resemble find_printk_buffer() ?
> > 
> > Adding KERN_UNSUPPRESSED to all printks down the op_p->handler()
> > line is hardly possible. At the same time I'd really prefer not
> > to have buffering for sysrq.
> 
> I don't think it is hardly possible. And I really prefer having
> deferred printing for SysRq.

Well, magic SysRq was meant for situation where system is in weird/broken state.
"Give me backtrace where it is hung", etc. Direct printing is more likely to work
in that cases.
									Pavel