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Kernel: Introduce the DeviceManagement singleton

This singleton simplifies many aspects that we struggled with before:
1. There's no need to make derived classes of Device expose the
constructor as public anymore. The singleton is a friend of them, so he
can call the constructor. This solves the issue with try_create_device
helper neatly, hopefully for good.
2. Getting a reference of the NullDevice is now being done from this
singleton, which means that NullDevice no longer needs to use its own
singleton, and we can apply the try_create_device helper on it too :)
3. We can now defer registration completely after the Device constructor
which means the Device constructor is merely assigning the major and
minor numbers of the Device, and the try_create_device helper ensures it
calls the after_inserting method immediately after construction. This
creates a great opportunity to make registration more OOM-safe.
This commit is contained in:
Liav A 2021-09-11 09:19:20 +03:00 committed by Idan Horowitz
parent 9aa6dd6b78
commit aee4786d8e
43 changed files with 244 additions and 123 deletions

View file

@ -5,22 +5,18 @@
*/
#include <AK/Singleton.h>
#include <Kernel/Devices/DeviceManagement.h>
#include <Kernel/Devices/NullDevice.h>
#include <Kernel/Sections.h>
namespace Kernel {
static Singleton<NullDevice> s_the;
UNMAP_AFTER_INIT void NullDevice::initialize()
UNMAP_AFTER_INIT NonnullRefPtr<NullDevice> NullDevice::must_initialize()
{
s_the.ensure_instance();
s_the->after_inserting();
}
NullDevice& NullDevice::the()
{
return *s_the;
auto null_device_or_error = DeviceManagement::try_create_device<NullDevice>();
// FIXME: Find a way to propagate errors
VERIFY(!null_device_or_error.is_error());
return null_device_or_error.release_value();
}
UNMAP_AFTER_INIT NullDevice::NullDevice()