ALSA: usb-audio: make hwc_debug a noop in case HW_CONST_DEBUG is not set

Just defining it to nothing is dangerous as it can alter the code
execution flow, for example when used in as only function in a
conditional code block.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/debug.h b/sound/usb/debug.h
index 343ec2d9ee6675ff2bea1016188a840418f4aadc..58030176f0083deef38d3d37b2ea46775cce58a0 100644 (file)
--- a/sound/usb/debug.h
+++ b/sound/usb/debug.h
@@ -8,7 +8,7 @@
 #ifdef HW_CONST_DEBUG
 #define hwc_debug(fmt, args...) printk(KERN_DEBUG fmt, ##args)
 #else
-#define hwc_debug(fmt, args...) /**/
+#define hwc_debug(fmt, args...) do { } while(0)
 #endif
 
 #endif /* __USBAUDIO_DEBUG_H */