linux-kernel - Re: [PATCH 1/2] printk: Add an option to flush all messages on panic

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Message-ID: <20190402022900.GA2219@jagdpanzerIV>
Date:   Tue, 2 Apr 2019 11:29:00 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Feng Tang <feng.tang@...el.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        Borislav Petkov <bp@...e.de>
Subject: Re: [PATCH 1/2] printk: Add an option to flush all messages on panic

On (04/02/19 10:28), Feng Tang wrote:
> > So my first thought was - let's not add a `bool flag', but instead add
> > an `enum' with clear flag names, e.g. DUMP_ALL/DUMP_PENDING, etc. Something
> > similar to what ftrace_dump(DUMP_ALL) does. And we already have panic_print
> > bit-mask and panic_print_sys_info(), which controls what we print when in
> > panic. So we can move console_flush_on_panic() to panic_print_sys_info()
> > and handle different types of console_flush_on_panic() there:
> > 
> > ---
> > 
> > diff --git a/kernel/panic.c b/kernel/panic.c
> > index 0ae0d7332f12..e142faaebbcd 100644
> > --- a/kernel/panic.c
> > +++ b/kernel/panic.c
> > @@ -134,6 +134,11 @@ EXPORT_SYMBOL(nmi_panic);
> >  
> >  static void panic_print_sys_info(void)
> >  {
> > +	if (panic_print & PANIC_PRINT_REPLAY_LOGBUF)
> > +		console_flush_on_panic(DUMP_ALL);
> > +	else
> > +		console_flush_on_panic(DUMP_PENDING);
> > +
> >  	if (panic_print & PANIC_PRINT_TASK_INFO)
> >  		show_state();
> >  
> > @@ -277,7 +282,6 @@ void panic(const char *fmt, ...)
> >  	 * panic() is not being callled from OOPS.
> >  	 */
> >  	debug_locks_off();
> > -	console_flush_on_panic();
> >  
> >  	panic_print_sys_info();
> >  
> 
> I guess this is what my 2/2 patch exactly does :)

Oh, indeed... I didn't check 2/2.

	-ss