linux-kernel - Re: [PATCH printk v1 05/13] printk: call boot_delay_msec() in printk

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Message-ID: <Ygxt13r9MWa4vnwG@google.com>
Date:   Wed, 16 Feb 2022 12:21:59 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        John Ogness <john.ogness@...utronix.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH printk v1 05/13] printk: call boot_delay_msec() in
 printk_delay()

On (22/02/15 15:59), Petr Mladek wrote:
> > > -static inline void printk_delay(void)
> > > +static inline void printk_delay(int level)
> > >  {
> > > +	boot_delay_msec(level);
> > > +
> > >  	if (unlikely(printk_delay_msec)) {
> > >  		int m = printk_delay_msec;
> > >  
> > > @@ -2224,8 +2226,7 @@ asmlinkage int vprintk_emit(int facility, int level,
> > >  		in_sched = true;
> > >  	}
> > >  
> > > -	boot_delay_msec(level);
> > > -	printk_delay();
> > > +	printk_delay(level);
> > 
> > As a side note, I wonder why do boot_delay_msec() and printk_delay()
> > touch only NMI watchdog. Shouldn't they also touch softlockup, WQ,
> > RCU, etc. watchdogs?
> 
> It seems that touch_nmi_watchdog() actually calls touch_softlockup_watchdog()
> that calls wq_watchdog_touch().

Oh, you are right, good point.

Well, we still have RCU stall detector which can trigger (in theory).