linux-kernel - Re: [patch] fix the softlockup watchdog to actually work

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Message-Id: <20070717143843.2a5cbf1b.randy.dunlap@oracle.com>
Date:	Tue, 17 Jul 2007 14:38:43 -0700
From:	Randy Dunlap <randy.dunlap@...cle.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Jeremy Fitzhardinge <jeremy@...p.org>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>, stable@...nel.org,
	Greg KH <greg@...ah.com>, Chris Wright <chrisw@...s-sol.org>
Subject: Re: [patch] fix the softlockup watchdog to actually work

On Tue, 17 Jul 2007 11:14:51 -0700 (PDT) Linus Torvalds wrote:

> On Tue, 17 Jul 2007, Randy Dunlap wrote:
> >
> > > +	if ((print_timestamp >= touch_timestamp &&
> > > +			print_timestamp < (touch_timestamp + 1)) ||
> > > +			did_panic || !per_cpu(watchdog_task, this_cpu)) {
> > >  		return;
> > > +	}
> > >  
> > >  	/* do not print during early bootup: */
> > >  	if (unlikely(system_state != SYSTEM_RUNNING)) {
> > 
> > patch contains unneeded braces { }.
> 
> When there are issues with indentation, those braces are actually not 
> unneeded any more, except for the compiler.
> 
> Just _look_ at the code. The indentation is not obvious, because the 
> if-conditional itself is multiple lines, and indented (arguably wrongly so 
> too, but that's another issue).

I strongly agree with your parenthetical remark and think that is
the real problem.


> So it's no longer a trivial one-liner statement, it's a "multi-statement" 
> spread out over multiple lines, and I think the braces are actually a good 
> idea for things like that.
> 
> I also encourage people do do braces when you have nested indentation, ie
> 
> 	if (something)
> 		if (somethingelse)
> 			return;

I think that this is wrong only when there is an "else" branch
following this.

> is actively *wrong*, while
> 
> 	if (something) {
> 		if (somethingelse)
> 			return;
> 	}
> 
> is right, even though the braces are "unnecessary". Again, it's about the 
> visual representation, not about whether the compiler needs them or not.

I agree with your last statement.
And thankfully none of this is in CodingStyle.  (oops)


---
~Randy
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