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/machzwd.c

diff --git a/drivers/char/watchdog/machzwd.c b/drivers/char/watchdog/machzwd.c
index 76c7fa3..a0d2716 100644
--- a/drivers/char/watchdog/machzwd.c
+++ b/drivers/char/watchdog/machzwd.c
@@ -440,13 +440,6 @@
 	spin_lock_init(&zf_lock);
 	spin_lock_init(&zf_port_lock);
 
-	ret = misc_register(&zf_miscdev);
-	if (ret){
-		printk(KERN_ERR "can't misc_register on minor=%d\n",
-							WATCHDOG_MINOR);
-		goto out;
-	}
-
 	if(!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")){
 		printk(KERN_ERR "cannot reserve I/O ports at %d\n",
 							ZF_IOBASE);
@@ -461,16 +454,23 @@
 		goto no_reboot;
 	}
 
+	ret = misc_register(&zf_miscdev);
+	if (ret){
+		printk(KERN_ERR "can't misc_register on minor=%d\n",
+							WATCHDOG_MINOR);
+		goto no_misc;
+	}
+
 	zf_set_status(0);
 	zf_set_control(0);
 
 	return 0;
 
+no_misc:
+	unregister_reboot_notifier(&zf_notifier);
 no_reboot:
 	release_region(ZF_IOBASE, 3);
 no_region:
-	misc_deregister(&zf_miscdev);
-out:
 	return ret;
 }