From mboxrd@z Thu Jan  1 00:00:00 1970
From: Joe Perches <joe@perches.com>
Subject: Re: New sparse warning in net/mac80211/debugfs_sta.c
Date: Mon, 25 Feb 2008 08:53:49 -0800
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Cc: David Miller <davem@davemloft.net>, kaber@trash.net,
	harvey.harrison@gmail.com, netdev@vger.kernel.org
To: Johannes Berg <johannes@sipsolutions.net>
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On Mon, 2008-02-25 at 10:53 +0100, Johannes Berg wrote:
> Maybe we should just add a new printf modifier like %M for MAC
> addresses? Then we could use sprintf, snprintf, printk and whatever we
> please without any of the macro stuff...

Could gcc validate the printf %M arguments?

Another possibility without changing printf argument validation
is to use a MAC_FMT macro in place of "%s"

#ifdef CONFIG_INLINE_MAC

#define MAC_FMT "%02x:%02x:%02x:%02x:%02x:%02x"
#define DECLARE_MAC_BUF(var)
#define print_mac(buf, addr) (addr)[0], (addr)[1], (addr)[2], (addr)[3], (addr)[4], (addr)[5]

#else

#define MAC_FMT "%s"
#define DECLARE_MAC_BUF(var) char var[18];
extern char *print_mac(char *buf, const unsigned char *addr);

#endif

use:

DECLARE_MAC_BUF(mac);
printk(KERN_INFO "Mac address is: " MAC_FMT "\n", print_mac(mac, addr));