watchdog: f71808e_wdt: Fix magic close handling

ipylypiv · Wim Van Sebroeck · commit 7bd3e7b74395 · 2018-03-03T15:52:32.000+01:00
Watchdog close is "expected" when any byte is 'V' not just the last one.
Writing "V" to the device fails because the last byte is the end of string.

$ echo V &gt; /dev/watchdog
f71808e_wdt: Unexpected close, not stopping watchdog!

Signed-off-by: Igor Pylypiv &lt;igor.pylypiv@gmail.com&gt;
Reviewed-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: Wim Van Sebroeck &lt;wim@iguana.be&gt;
diff --git a/drivers/watchdog/f71808e_wdt.c b/drivers/watchdog/f71808e_wdt.c
@@ -566,7 +566,8 @@ static ssize_t watchdog_write(struct file *file, const char __user *buf,
 				char c;
 				if (get_user(c, buf + i))
 					return -EFAULT;
-				expect_close = (c == 'V');
+				if (c == 'V')
+					expect_close = true;
 			}
 
 			/* Properly order writes across fork()ed processes */

Original file line number	Diff line number	Diff line change
`@@ -566,7 +566,8 @@ static ssize_t watchdog_write(struct file file, const char __user buf,`
`566`	`566`	`char c;`
`567`	`567`	`if (get_user(c, buf + i))`
`568`	`568`	`return -EFAULT;`
`569`		`- expect_close = (c == 'V');`
	`569`	`+ if (c == 'V')`
	`570`	`+ expect_close = true;`
`570`	`571`	`}`
`571`	`572`
`572`	`573`	`/* Properly order writes across fork()ed processes */`