commit fb8f7ba077b5c665432082ab205bcd2cb01f6a3c
author Alexey Dobriyan <adobriyan@gmail.com> Sat Mar 24 15:58:12 2007 +0300
committer Wim Van Sebroeck <wim@iguana.be> Mon Mar 26 20:26:11 2007 +0000
tree 13a956eb9a1723bd3d5463230acbfc6513f3b034
parent 0e94f2ee0d1947ba6c2c00c3e971ff93ce8edec1

[WATCHDOG] Semi-typical watchdog bug re early misc_register()

It seems that some watchdog drivers are doing following mistake:

	rv = misc_register();
	if (rv < 0)
		return rv;
	rv = request_region();
	if (rv < 0) {
		misc_deregister();
		return rv;
	}

But, right after misc_register() returns, misc device can be opened and
ioctls interacting with hardware issued, and driver can do outb() to
port it doesn't own yet, because request_region() is still pending.

Here is my patch, compile-tested only.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/char/watchdog/cpu5wdt.c

diff --git a/drivers/char/watchdog/cpu5wdt.c b/drivers/char/watchdog/cpu5wdt.c
index bcd7e36..d0d45a8 100644
--- a/drivers/char/watchdog/cpu5wdt.c
+++ b/drivers/char/watchdog/cpu5wdt.c
@@ -220,17 +220,17 @@
 	if ( verbose )
 		printk(KERN_DEBUG PFX "port=0x%x, verbose=%i\n", port, verbose);
 
-	if ( (err = misc_register(&cpu5wdt_misc)) < 0 ) {
-		printk(KERN_ERR PFX "misc_register failed\n");
-		goto no_misc;
-	}
-
 	if ( !request_region(port, CPU5WDT_EXTENT, PFX) ) {
 		printk(KERN_ERR PFX "request_region failed\n");
 		err = -EBUSY;
 		goto no_port;
 	}
 
+	if ( (err = misc_register(&cpu5wdt_misc)) < 0 ) {
+		printk(KERN_ERR PFX "misc_register failed\n");
+		goto no_misc;
+	}
+
 	/* watchdog reboot? */
 	val = inb(port + CPU5WDT_STATUS_REG);
 	val = (val >> 2) & 1;
@@ -250,9 +250,9 @@
 
 	return 0;
 
-no_port:
-	misc_deregister(&cpu5wdt_misc);
 no_misc:
+	release_region(port, CPU5WDT_EXTENT);
+no_port:
 	return err;
 }