linux-kernel - Re: [PATCH 0/3] x86/dumpstack: Print registers with the same log level as the backtrace

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Message-ID: <20200624065054.GC8444@alley>
Date:   Wed, 24 Jun 2020 08:50:54 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Dmitry Safonov <dima@...sta.com>
Cc:     linux-kernel@...r.kernel.org,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Jann Horn <jannh@...gle.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org
Subject: Re: [PATCH 0/3] x86/dumpstack: Print registers with the same log
 level as the backtrace

On Tue 2020-06-23 17:29:55, Dmitry Safonov wrote:
> show_trace_log_lvl() provides x86 platform-specific way to unwind
> backtrace with a given log level. Unfortunately, registers dump(s) are
> not printed with the same log level - instead, KERN_DEFAULT is always
> used.
> 
> Arista's switches uses quite common setup with rsyslog, where only
> urgent messages goes to console (console_log_level=KERN_ERR), everything
> else goes into /var/log/ as the console baud-rate often is indecently
> slow (9600 bps).
> 
> Backtrace dumps without registers printed have proven to be as useful as
> morning standups. Furthermore, in order to introduce KERN_UNSUPPRESSED
> (which I believe is still the most elegant way to fix raciness of sysrq[1])
> the log level should be passed down the stack to register dumping
> functions. Besides, I have a potential use-case for printing traces
> with KERN_DEBUG level [2] (where registers dump shouldn't appear with
> higher log level than the backtrace).
> 
> Dmitry Safonov (3):
>   x86/dumpstack: Add log_lvl to show_iret_regs()
>   x86/dumpstack: Add log_lvl to __show_regs()
>   x86/dumpstack: Show registers dump with trace's log level

The change makes sense. It is natural next step after adding log_lvl
parameter for printing stack traces. For the entire patchset:

Acked-by: Petr Mladek <pmladek@...e.com>

Are there any plans to add this also for other architectures, please?

Best Regards,
Petr