linux-kernel - Re: [PATCH 3/4] SunRPC: Use no_printk() for the null dprintk() and dfprintk()

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Date:	Thu, 26 Sep 2013 08:30:15 -0700
From:	Joe Perches <joe@...ches.com>
To:	David Howells <dhowells@...hat.com>
Cc:	bfields@...ldses.org, Trond.Myklebust@...app.com, olof@...om.net,
	linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] SunRPC: Use no_printk() for the null dprintk() and
 dfprintk()

On Thu, 2013-09-26 at 15:45 +0100, David Howells wrote:
> Use no_printk() for the null dprintk() and dfprintk() so that the compiler
> doesn't complain about unused variables for stuff that's just printed.

no_printk doesn't prevent any argument side-effects
from being optimized away by the compiler.

ie:
	dprintk("%d", func())
func is now always called when before it wasn't.

Are there any side-effects?

btw: Using

#define dprintk(fmt, ...)
do {
	if (0)
		printk(fmt, ##__VA_ARGS__);
} while (0)

does away with side-effects.


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