linux-kernel - [PATCH] [media] m920x: let GCC see 'ret' is used initialized

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Message-ID: <1362404600.16460.26.camel@x61.thuisdomein>
Date:	Mon, 04 Mar 2013 14:43:20 +0100
From:	Paul Bolle <pebolle@...cali.nl>
To:	Mauro Carvalho Chehab <mchehab@...hat.com>
Cc:	Antonio Ospite <ospite@...denti.unina.it>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] [media] m920x: let GCC see 'ret' is used initialized

Since commit 7543f344e9b06afe86b55a2620f5c11b38bd5642 ("[media] m920x:
factor out a m920x_write_seq() function") building m920x.o triggers this
GCC warning:
    drivers/media/usb/dvb-usb/m920x.c: In function ‘m920x_probe’:
    drivers/media/usb/dvb-usb/m920x.c:91:6: warning: ‘ret’ may be used uninitialized in this function [-Wuninitialized]

This warning is caused by m920x_write_seq(), which is apparently inlined
into m920x_probe(). It is clear why GCC thinks 'ret' may be used
uninitialized. But in practice the first seq->address will always be
non-zero when this function is called. That means we can change the
while()-do{} loop into a do{}-while() loop. And that suffices to make
GCC see that 'ret' will not be used uninitialized.

Signed-off-by: Paul Bolle <pebolle@...cali.nl>
---
Compile tested only!

 drivers/media/usb/dvb-usb/m920x.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/dvb-usb/m920x.c b/drivers/media/usb/dvb-usb/m920x.c
index 92afeb2..79b31ae 100644
--- a/drivers/media/usb/dvb-usb/m920x.c
+++ b/drivers/media/usb/dvb-usb/m920x.c
@@ -68,13 +68,13 @@ static inline int m920x_write_seq(struct usb_device *udev, u8 request,
 				  struct m920x_inits *seq)
 {
 	int ret;
-	while (seq->address) {
+	do {
 		ret = m920x_write(udev, request, seq->data, seq->address);
 		if (ret != 0)
 			return ret;
 
 		seq++;
-	}
+	} while (seq->address);
 
 	return ret;
 }
-- 
1.7.11.7

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