Re: Exit ACPI drivers immediately if acpi is disabled

[Bjorn Helgaas <bjorn.helgaas@hp.com>]

On Friday 21 April 2006 04:43, Thomas Renninger wrote:
> If booting with acpi=off and loading the processor module, it
> may happen that the kernel oopses when trying to unload the module again.
> Better exit all ACPI modules immediately if booted with acpi=off.
> ... 
> @@ -289,31 +289,28 @@ static int __init acpi_ac_init(void)
>  {
>  	int result = 0;
>  
> -	ACPI_FUNCTION_TRACE("acpi_ac_init");
> +	if (acpi_disabled)
> +		return -ENODEV;

This doesn't feel like the right solution to me.
acpi_bus_register_driver() already returns -ENODEV
if acpi_disabled, and that ought to be enough so the
drivers can handle this correctly.

I don't think we should clutter every ACPI driver with
the same check for acpi_disabled.

Did you investigate the oops when unloading the processor module?
I wonder if that driver has a bug there.  It has a mysterious
comment that "we keep the driver loaded even when ACPI is not
running" for powernow-k8.   I don't understand that at all, but
it sounds like it requires extra care to make sure everything
works right.