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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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3
Kernel/FileSystem/DevPtsFS.cpp
View file

@ -5,6 +5,7 @@
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/Devices/DeviceManagement.h>
#include <Kernel/FileSystem/DevPtsFS.h>
#include <Kernel/FileSystem/VirtualFileSystem.h>
#include <Kernel/TTY/SlavePTY.h>
@ -58,7 +59,7 @@ KResultOr<NonnullRefPtr<Inode>> DevPtsFS::get_inode(InodeIdentifier inode_id) co
return *m_root_inode;
unsigned pty_index = inode_index_to_pty_index(inode_id.index());
auto* device = Device::get_device(201, pty_index);
auto* device = DeviceManagement::the().get_device(201, pty_index);
VERIFY(device);
auto inode = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) DevPtsFSInode(const_cast<DevPtsFS&>(*this), inode_id.index(), static_cast<SlavePTY*>(device))));

5
Kernel/FileSystem/DevTmpFS.cpp
View file

@ -5,6 +5,7 @@
*/
#include <AK/StringView.h>
#include <Kernel/Devices/DeviceManagement.h>
#include <Kernel/FileSystem/DevTmpFS.h>
#include <Kernel/FileSystem/VirtualFileSystem.h>
@ -321,7 +322,7 @@ KResultOr<size_t> DevTmpFSDeviceInode::read_bytes(off_t offset, size_t count, Us
{
MutexLocker locker(m_inode_lock);
VERIFY(!!description);
RefPtr<Device> device = Device::get_device(m_major_number, m_minor_number);
RefPtr<Device> device = DeviceManagement::the().get_device(m_major_number, m_minor_number);
if (!device)
return KResult(ENODEV);
if (!device->can_read(*description, offset))
@ -336,7 +337,7 @@ KResultOr<size_t> DevTmpFSDeviceInode::write_bytes(off_t offset, size_t count, c
{
MutexLocker locker(m_inode_lock);
VERIFY(!!description);
RefPtr<Device> device = Device::get_device(m_major_number, m_minor_number);
RefPtr<Device> device = DeviceManagement::the().get_device(m_major_number, m_minor_number);
if (!device)
return KResult(ENODEV);
if (!device->can_write(*description, offset))

3
Kernel/FileSystem/VirtualFileSystem.cpp
View file

@ -9,6 +9,7 @@
#include <AK/StringBuilder.h>
#include <Kernel/Debug.h>
#include <Kernel/Devices/BlockDevice.h>
#include <Kernel/Devices/DeviceManagement.h>
#include <Kernel/FileSystem/Custody.h>
#include <Kernel/FileSystem/FileBackedFileSystem.h>
#include <Kernel/FileSystem/FileSystem.h>
@ -270,7 +271,7 @@ KResultOr<NonnullRefPtr<OpenFileDescription>> VirtualFileSystem::open(StringView
if (metadata.is_device()) {
if (custody.mount_flags() & MS_NODEV)
return EACCES;
auto device = Device::get_device(metadata.major_device, metadata.minor_device);
auto device = DeviceManagement::the().get_device(metadata.major_device, metadata.minor_device);
if (device == nullptr) {
return ENODEV;
}