[PATCH] watchdog/iTCO_wdt: fix bug related to gcc uninit warning

[PATCH] watchdog/iTCO_wdt: fix bug related to gcc uninit warning

[Jeff Garzik]

gcc emits the following warning:

drivers/char/watchdog/iTCO_wdt.c: In function ‘iTCO_wdt_ioctl’:
drivers/char/watchdog/iTCO_wdt.c:429: warning: ‘time_left’ may be used uninitialized in this function

This indicates a condition near enough to a bug, to want to fix.
iTCO_wdt_get_timeleft() stores a value in 'time_left' iff
iTCO_version==(1 or 2).  This driver only supports versions
1 or 2, so this is ok.  However, since (a) the return value of
iTCO_wdt_get_timeleft() is handled anyway, (b) it fixes the warning,
and (c) it future-proofs the driver, we go ahead and add the obvious
return value.

Signed-off-by: Jeff Garzik <jeff@garzik.org>

---

 drivers/char/watchdog/iTCO_wdt.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/char/watchdog/iTCO_wdt.c b/drivers/char/watchdog/iTCO_wdt.c
index aaac94d..bf5cd55 100644
--- a/drivers/char/watchdog/iTCO_wdt.c
+++ b/drivers/char/watchdog/iTCO_wdt.c
@@ -355,7 +355,8 @@ static int iTCO_wdt_get_timeleft (int *t
 		spin_unlock(&iTCO_wdt_private.io_lock);
 
 		*time_left = (val8 * 6) / 10;
-	}
+	} else
+		return -EINVAL;
 	return 0;
 }
 
@@ -426,7 +427,6 @@ static int iTCO_wdt_ioctl (struct inode 
 {
 	int new_options, retval = -EINVAL;
 	int new_heartbeat;
-	int time_left;
 	void __user *argp = (void __user *)arg;
 	int __user *p = argp;
 	static struct watchdog_info ident = {
@@ -486,6 +486,8 @@ static int iTCO_wdt_ioctl (struct inode 
 
 		case WDIOC_GETTIMELEFT:
 		{
+			int time_left;
+
 			if (iTCO_wdt_get_timeleft(&time_left))
 				return -EINVAL;
 

Re: [PATCH] watchdog/iTCO_wdt: fix bug related to gcc uninit warning

[Wim Van Sebroeck]

Hi Jeff,

> gcc emits the following warning:
> 
> drivers/char/watchdog/iTCO_wdt.c: In function ‘iTCO_wdt_ioctl’:
> drivers/char/watchdog/iTCO_wdt.c:429: warning: ‘time_left’ may be used uninitialized in this function

Don't know how I missed that.
Anyway: patch applied to my linux-2.6-watchdog-mm tree.

Thanks,
Wim.