pr_debug and "if (0)" statement

[luca ellero <lroluk@xxxxxxxxx>]

Hi all,

looking into kernel source code (2.6.26.8) I encountered this definition 
(in include/linux/kernel.h):

#ifdef DEBUG
/* If you are writing a driver, please use dev_dbg instead */
#define pr_debug(fmt, arg...) \
	printk(KERN_DEBUG fmt, ##arg)
#else
#define pr_debug(fmt, arg...) \
	({ if (0) printk(KERN_DEBUG fmt, ##arg); 0; })
#endif


can someone please explain me the meaning/benefits of the "if (0)" 
statement?


Thanks

Regards

Luca


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