Re: Semi-typical watchdog bug re early misc_register()

[Wim Van Sebroeck]

Hi Alexey,

> 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.

Totally agree. patch has been added to linux-2.6-watchdog-mm tree.

> Also, is there similar ordering between register_reboot_notifier() and
> misc_register() ? Some drivers do misc_register() last, some register
> reboot notifiers.

I prefer that the reboot notifiers are loaded before you give userspace the
ability to communicate with the driver.

Greetings,
Wim.

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