* Serialize calls to acpi_alloc_resource(), acpi_release_resource(),
acpi_Enable(), acpi_Disable(), and acpi_debug_sysctl().
* Acquire the ACPI mutex in acpi_register_ioctl(), acpi_deregister_ioctl(),
and acpiioctl().
* Acquire the mutex while disabling subsequent requests to enter a
sleep state in acpi_SetSleepState().
* Be sure to re-enable sleep requests and don't run resume methods when
the current request fails.
* Don't check if sleep requests are disabled in the ACPIIO_SETSLPSTATE
ioctl. acpi_SetSleepState() does this for us.
* Remove the acquisition of Giant from the struct cdevsw.
* Remove the ACPI_USE_THREADS option.