Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Fri, 6 Jan 2023 10:34:47 +0100
From:   Petr Mladek <pmladek@suse.com>
To:     John Ogness <john.ogness@linutronix.de>
Cc:     Sergey Senozhatsky <senozhatsky@chromium.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH printk v4 6/8] printk: introduce
 console_prepend_dropped() for dropped messages
Message-ID: <Y7frNwBA06hMivMl@alley>
References: <20230105103735.880956-1-john.ogness@linutronix.de>
 <20230105103735.880956-7-john.ogness@linutronix.de>
 <Y7b4AND0DRs7jPW9@alley>
 <87y1qhaqhc.fsf@jogness.linutronix.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <87y1qhaqhc.fsf@jogness.linutronix.de>
Precedence: bulk

On Thu 2023-01-05 17:41:59, John Ogness wrote:
> On 2023-01-05, Petr Mladek <pmladek@suse.com> wrote:
> >> +	if (WARN_ON_ONCE(len + PREFIX_MAX >= outbuf_sz))
> >> +		return;
> >
> > I guess that this will always trigger the compiler warning
> > when CONFIG_PRINTK is disabled. See the report for v3 at
> > https://lore.kernel.org/r/202301052114.vvN3wQoH-lkp@intel.com
> 
> That report is actually complaining about the check after this one. It
> is the same "problem".

I see.

> > Hmm, we might want to fix this warning so that it does not break
> > build with -Werror.
> >
> > IMHO, the proper solution would be to define this function only when
> > CONFIG_PRINTK is defined. But it might require bigger changes
> > and define many more console functions only when CONFIG_PRINTK
> > is defined. This is out-of-scope of this patchset.
> >
> > I wonder if the following would work as an "intermediate" workaround:
> >
> > 	if (!IS_ENABLED(CONFIG_PRINTK) ||
> > 	    WARN_ON_ONCE(len + PREFIX_MAX >= outbuf_sz))
> > 		return;
> 
> The whole CONFIG_PRINTK stuff is a total mess right now. We should
> definitely get that cleaned up at some point. As an intermediate
> workaround, it might make more sense to just put the whole function
> inside an "#ifdef CONFIG_PRINTK". It doesn't return anything anyway.
> 
> #ifdef CONFIG_PRINTK
> static void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped)
> {
> ...
> }
> #else
> #define console_prepend_dropped(pmsg, dropped)
> #endif

Looks good.

The question is if we want to do it in this patch or as a follow up
fix.

I slightly prefer to do it as a follow up fix to avoid another respin.
Also we will not need to complicate this patch with explaining
why this is needed.

Best Regards,
Petr