linux-kernel - Re: [PATCH wireless-next 2/3] ath5k: Introduce _ath5k

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Message-ID: <1332215281.7847.54.camel@joe2Laptop>
Date:	Mon, 19 Mar 2012 20:48:01 -0700
From:	Joe Perches <joe@...ches.com>
To:	Adrian Chadd <adrian@...ebsd.org>
Cc:	Jiri Slaby <jirislaby@...il.com>,
	Nick Kossifidis <mickflemm@...il.com>,
	"Luis R. Rodriguez" <mcgrof@....qualcomm.com>,
	Bob Copeland <me@...copeland.com>,
	"John W. Linville" <linville@...driver.com>,
	linux-wireless@...r.kernel.org, ath5k-devel@...ts.ath5k.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH wireless-next 2/3] ath5k: Introduce _ath5k_printk to
 reduce code/text

On Mon, 2012-03-19 at 20:39 -0700, Adrian Chadd wrote:
> On 18 March 2012 22:18, Joe Perches <joe@...ches.com> wrote:
> >> Otherwise compiling in debugging will cause a _lot_ of spurious
> >> register reads to occur that are then tossed. This was one of the big
> >> reasons for instability and slow performance when AH_DEBUG was
> >> enabled.
> > That doesn't make any sense in this case.
> >
> > It's either a call to printk or _ath5_printk
> > but it's still a call to a function.
> 
> The FreeBSD HAL used to be like this. I changed it so it didn't
> evaluate the arguments before it figured out whether or not to do the
> (k)printf().
> 
> I'm just pointing it out as you're (currently) knee deep in the
> debugging code and it may be useful for you to also think about
> implementing.

I see, thanks for the heads-up.

The no_printk function could/does eval args
and can cause those sorts of issues.

So care does need to be used.

cheers, Joe

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