-----Original Message-----
From: linux-omap-owner@vger.kernel.org 
[mailto:linux-omap-owner@vger.kernel.org] On Behalf Of Niels de Vos
Sent: Tuesday, May 10, 2011 2:51 PM
To: linux-omap@vger.kernel.org
Cc: linux-fbdev@vger.kernel.org; 
linux-kernel@vger.kernel.org; Niels de Vos
Subject: [PATCH] omap2/omapfb: make DBG() more resistant in 
if-else constructions

When DBG() is used in a simple if-else, the resulting code path
currently depends on the definition of DBG(). Inserting the 
statement in
a "do { ... } while (0)" prevents this possible misuse.

Signed-off-by: Niels de Vos <redacted>

---
Note, I have not found any offenders, but a mistake can 
easily be made.
The following example shows what can go wrong if little intention is
paid to the definition of the DBG() macro.

Example:
	if something_went_wrong()
		DBG("oh no, something went wrong!\n");
	else
		printk("all went fine\n");

Old result where the else is placed inside the first if-statment:
	if something_went_wrong() {
		if (omapfb_debug) {
			printk(KERN_DEBUG "oh no, something 
went wrong!\n");
		} else {
			printk("all went fine\n");
		}
	}

New result where the else is an alternative to the first if-statement:
	if something_went_wrong() {
		do {
			if (omapfb_debug)
				printk(KERN_DEBUG "oh no, 
something went wrong!\n");
		} while (0);
	} else {
		printk("all went fine\n");
	}
---
 drivers/video/omap2/omapfb/omapfb.h |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/video/omap2/omapfb/omapfb.h 

b/drivers/video/omap2/omapfb/omapfb.h
index 1305fc9..a01b0bb 100644

--- a/drivers/video/omap2/omapfb/omapfb.h
+++ b/drivers/video/omap2/omapfb/omapfb.h

@@ -34,8 +34,10 @@
 #ifdef DEBUG
 extern unsigned int omapfb_debug;
 #define DBG(format, ...) \
-	if (omapfb_debug) \
-		printk(KERN_DEBUG "OMAPFB: " format, ## __VA_ARGS__)
+	do { \
+		if (omapfb_debug) \
+			printk(KERN_DEBUG "OMAPFB: " format, ## 

__VA_ARGS__); \
+	while (0)