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Kernel: Introduce the DeviceManagement singleton

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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
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45
Kernel/Devices/Device.cpp
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@ -6,20 +6,13 @@
#include <AK/Singleton.h>
#include <Kernel/Devices/Device.h>
#include <Kernel/Devices/DeviceManagement.h>
#include <Kernel/FileSystem/InodeMetadata.h>
#include <Kernel/FileSystem/SysFS.h>
#include <Kernel/Locking/MutexProtected.h>
#include <Kernel/Sections.h>
namespace Kernel {
static Singleton<MutexProtected<HashMap<u32, Device*>>> s_all_devices;
MutexProtected<HashMap<u32, Device*>>& Device::all_devices()
{
return *s_all_devices;
}
NonnullRefPtr<SysFSDeviceComponent> SysFSDeviceComponent::must_create(Device const& device)
{
return adopt_ref_if_nonnull(new SysFSDeviceComponent(device)).release_nonnull();
@ -115,41 +108,15 @@ RefPtr<SysFSComponent> SysFSCharacterDevicesDirectory::lookup(StringView name)
});
}
void Device::for_each(Function<void(Device&)> callback)
{
all_devices().with_exclusive([&](auto& map) -> void {
for (auto& entry : map)
callback(*entry.value);
});
}
Device* Device::get_device(unsigned major, unsigned minor)
{
return all_devices().with_exclusive([&](auto& map) -> Device* {
auto it = map.find(encoded_device(major, minor));
if (it == map.end())
return nullptr;
return it->value;
});
}
Device::Device(unsigned major, unsigned minor)
: m_major(major)
, m_minor(minor)
{
u32 device_id = encoded_device(major, minor);
all_devices().with_exclusive([&](auto& map) -> void {
auto it = map.find(device_id);
if (it != map.end()) {
dbgln("Already registered {},{}: {}", major, minor, it->value->class_name());
}
VERIFY(!map.contains(device_id));
map.set(device_id, this);
});
}
void Device::after_inserting()
{
DeviceManagement::the().after_inserting_device({}, *this);
VERIFY(!m_sysfs_component);
auto sys_fs_component = SysFSDeviceComponent::must_create(*this);
m_sysfs_component = sys_fs_component;
@ -160,21 +127,17 @@ void Device::after_inserting()
void Device::before_removing()
{
m_state = State::BeingRemoved;
VERIFY(m_sysfs_component);
SysFSComponentRegistry::the().devices_list().with_exclusive([&](auto& list) -> void {
list.remove(*m_sysfs_component);
});
DeviceManagement::the().before_device_removal({}, *this);
m_state = State::BeingRemoved;
}
Device::~Device()
{
VERIFY(m_state == State::BeingRemoved);
u32 device_id = encoded_device(m_major, m_minor);
all_devices().with_exclusive([&](auto& map) -> void {
VERIFY(map.contains(device_id));
map.remove(encoded_device(m_major, m_minor));
});
}
String Device::absolute_path() const