linux-kernel - Re: [PATCH] panic: only warn about deprecated panic

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Message-ID: <aV_SzomLHKZ19U98@pathway.suse.cz>
Date: Thu, 8 Jan 2026 16:52:46 +0100
From: Petr Mladek <pmladek@...e.com>
To: Feng Tang <feng.tang@...ux.alibaba.com>
Cc: Gal Pressman <gal@...dia.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Mark Bloch <mbloch@...dia.com>,
	Nimrod Oren <noren@...dia.com>
Subject: Re: [PATCH] panic: only warn about deprecated panic_print on write
 access

On Wed 2026-01-07 15:20:44, Feng Tang wrote:
> On Wed, Jan 07, 2026 at 08:41:22AM +0200, Gal Pressman wrote:
> > On 07/01/2026 5:00, Feng Tang wrote:
> > >> @@ -1014,7 +1015,6 @@ static int panic_print_set(const char *val, const struct kernel_param *kp)
> > >>  
> > >>  static int panic_print_get(char *val, const struct kernel_param *kp)
> > >>  {
> > >> -	panic_print_deprecated();
> > > 
> > > Actually this was intentional, in one of the patch version, this
> > > panic_print_get() was not there but reusing the param_get_ulong().
> > > 
> > > It was added later as sometimes developer do want to runtime check
> > > the current 'panic_print' setting through /sys/module/kernel/parameters/
> > > interface, and I thought it may be better to give the warning.
> > 
> > I figured it would make sense to keep the behaviors consistent.

I see.

> When people run 'sysctl -a', in 99.9% cases, the users don't care
> 'panic_print' or even don't know what 'panic_print' is, that's why
> I think removing it makes sense.
>
> But for a user running 'cat /sys/module/kernel/parameters/panic_rint',
> giving a warning is meaningful.

Makes perfect sense.

We need to make people aware that "panic_print" will eventually go
away. 'sysctl -a' is different because it prints all values and
there is big chance that the caller is not interested in "panic_print"
at all.

It makes sense to remove the warning from sysctl read. But I would
keep it in sysfs read.

Best Regards,
Petr