linux-kernel - Re: [PATCH] staging: nvec: fixed few coding style warnings

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Message-ID: <20151015084812.GP7289@mwanda>
Date:	Thu, 15 Oct 2015 11:48:12 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Marc Dietrich <marvin24@....de>
Cc:	gregkh@...uxfoundation.org, linux-tegra@...r.kernel.org,
	Sakshi Bansal <sakshi.april5@...il.com>,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: nvec: fixed few coding style warnings

On Thu, Oct 15, 2015 at 10:39:02AM +0200, Marc Dietrich wrote:
> > > -			if (unlikely(nvec->rx == NULL)) {
> > > +			if (!unlikely(nvec->rx)) {
> > 
> > This isn't right.  You intented to say:
> > 
> > 	if (unlikely(!nvec->rx)) {
> > 
> > But even better to just remove the unlikely entirely.
> > 
> > 	if (!nvec->rx) {
> 
> why? the "unlikely" is there to optimize a critical interrupt path.

The rule is that drivers should not use likely/unlikely() unless there
is a difference in benchmark numbers.  How critical can it be when it's
always followed by a udelay(100)???

There are more important optimizations needed here.

regards,
dan carpenter

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