linux-kernel - Re: [PATCHv7 4/8] printk: always use deferred printk when flush printk

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Date:   Thu, 2 Feb 2017 16:37:54 +0100
From:   Petr Mladek <pmladek@...e.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Jan Kara <jack@...e.cz>, Tejun Heo <tj@...nel.org>,
        Calvin Owens <calvinowens@...com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Hurley <peter@...leysoftware.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCHv7 4/8] printk: always use deferred printk when flush
 printk_safe lines

On Thu 2017-02-02 15:05:38, Sergey Senozhatsky wrote:
> On (02/01/17 11:06), Steven Rostedt wrote:
> [..]
> > >  static void printk_safe_flush_line(const char *text, int len)
> > >  {
> > >  	/*
> > > -	 * The buffers are flushed in NMI only on panic.  The messages must
> > > -	 * go only into the ring buffer at this stage.  Consoles will get
> > > -	 * explicitly called later when a crashdump is not generated.
> > > +	 * Avoid any console drivers calls from here, because we may be
> > > +	 * in NMI or printk_safe context (when in panic). The messages
> > > +	 * must go only into the ring buffer at this stage.  Consoles will
> > > +	 * get explicitly called later when a crashdump is not generated.
> > >  	 */
> > > -	if (in_nmi())
> > > -		printk_deferred("%.*s", len, text);
> > > -	else
> > > -		printk("%.*s", len, text);
> > > +	printk_deferred("%.*s", len, text);
> > >  }
> > 
> > The helper function was there because of the if statement. Just nuke
> > this function and call printk_deferred() directly. You can move the
> > comment to the caller.
> 
> indeed. thanks.
> 
> Petr, how would you prefer to handle this?

I am still learning how to manage the patches in the printk.git tree.

I would like to add Steven's Reviewed-by tags, links to the mails,
and list of CC-ed people. IMHO, the only way is to rebase the for-4.11
and for-next branches. Then I could do the above suggested change during
the rebase.

Any other solutions are welcome. I will wait with the rebase at least
until Monday. We are discussing the lockdep in the 6th patch anyway.

Best Regards,
Petr