forked from suyu/suyu
127 lines
4 KiB
C++
127 lines
4 KiB
C++
// Copyright 2021 yuzu Emulator Project
|
|
// Licensed under GPLv2 or any later version
|
|
// Refer to the license.txt file included.
|
|
|
|
#include "core/hle/kernel/k_light_lock.h"
|
|
#include "core/hle/kernel/k_scheduler.h"
|
|
#include "core/hle/kernel/k_thread.h"
|
|
#include "core/hle/kernel/k_thread_queue.h"
|
|
#include "core/hle/kernel/kernel.h"
|
|
|
|
namespace Kernel {
|
|
|
|
namespace {
|
|
|
|
class ThreadQueueImplForKLightLock final : public KThreadQueue {
|
|
public:
|
|
explicit ThreadQueueImplForKLightLock(KernelCore& kernel_) : KThreadQueue(kernel_) {}
|
|
|
|
void CancelWait(KThread* waiting_thread, ResultCode wait_result,
|
|
bool cancel_timer_task) override {
|
|
// Remove the thread as a waiter from its owner.
|
|
if (KThread* owner = waiting_thread->GetLockOwner(); owner != nullptr) {
|
|
owner->RemoveWaiter(waiting_thread);
|
|
}
|
|
|
|
// Invoke the base cancel wait handler.
|
|
KThreadQueue::CancelWait(waiting_thread, wait_result, cancel_timer_task);
|
|
}
|
|
};
|
|
|
|
} // namespace
|
|
|
|
void KLightLock::Lock() {
|
|
const uintptr_t cur_thread = reinterpret_cast<uintptr_t>(GetCurrentThreadPointer(kernel));
|
|
|
|
while (true) {
|
|
uintptr_t old_tag = tag.load(std::memory_order_relaxed);
|
|
|
|
while (!tag.compare_exchange_weak(old_tag, (old_tag == 0) ? cur_thread : (old_tag | 1),
|
|
std::memory_order_acquire)) {
|
|
}
|
|
|
|
if (old_tag == 0 || this->LockSlowPath(old_tag | 1, cur_thread)) {
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
void KLightLock::Unlock() {
|
|
const uintptr_t cur_thread = reinterpret_cast<uintptr_t>(GetCurrentThreadPointer(kernel));
|
|
|
|
uintptr_t expected = cur_thread;
|
|
if (!tag.compare_exchange_strong(expected, 0, std::memory_order_release)) {
|
|
this->UnlockSlowPath(cur_thread);
|
|
}
|
|
}
|
|
|
|
bool KLightLock::LockSlowPath(uintptr_t _owner, uintptr_t _cur_thread) {
|
|
KThread* cur_thread = reinterpret_cast<KThread*>(_cur_thread);
|
|
ThreadQueueImplForKLightLock wait_queue(kernel);
|
|
|
|
// Pend the current thread waiting on the owner thread.
|
|
{
|
|
KScopedSchedulerLock sl{kernel};
|
|
|
|
// Ensure we actually have locking to do.
|
|
if (tag.load(std::memory_order_relaxed) != _owner) {
|
|
return false;
|
|
}
|
|
|
|
// Add the current thread as a waiter on the owner.
|
|
KThread* owner_thread = reinterpret_cast<KThread*>(_owner & ~1ULL);
|
|
cur_thread->SetAddressKey(reinterpret_cast<uintptr_t>(std::addressof(tag)));
|
|
owner_thread->AddWaiter(cur_thread);
|
|
|
|
// Begin waiting to hold the lock.
|
|
cur_thread->BeginWait(std::addressof(wait_queue));
|
|
|
|
if (owner_thread->IsSuspended()) {
|
|
owner_thread->ContinueIfHasKernelWaiters();
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
void KLightLock::UnlockSlowPath(uintptr_t _cur_thread) {
|
|
KThread* owner_thread = reinterpret_cast<KThread*>(_cur_thread);
|
|
|
|
// Unlock.
|
|
{
|
|
KScopedSchedulerLock sl(kernel);
|
|
|
|
// Get the next owner.
|
|
s32 num_waiters;
|
|
KThread* next_owner = owner_thread->RemoveWaiterByKey(
|
|
std::addressof(num_waiters), reinterpret_cast<uintptr_t>(std::addressof(tag)));
|
|
|
|
// Pass the lock to the next owner.
|
|
uintptr_t next_tag = 0;
|
|
if (next_owner != nullptr) {
|
|
next_tag =
|
|
reinterpret_cast<uintptr_t>(next_owner) | static_cast<uintptr_t>(num_waiters > 1);
|
|
|
|
next_owner->EndWait(ResultSuccess);
|
|
|
|
if (next_owner->IsSuspended()) {
|
|
next_owner->ContinueIfHasKernelWaiters();
|
|
}
|
|
}
|
|
|
|
// We may have unsuspended in the process of acquiring the lock, so we'll re-suspend now if
|
|
// so.
|
|
if (owner_thread->IsSuspended()) {
|
|
owner_thread->TrySuspend();
|
|
}
|
|
|
|
// Write the new tag value.
|
|
tag.store(next_tag, std::memory_order_release);
|
|
}
|
|
}
|
|
|
|
bool KLightLock::IsLockedByCurrentThread() const {
|
|
return (tag | 1ULL) == (reinterpret_cast<uintptr_t>(GetCurrentThreadPointer(kernel)) | 1ULL);
|
|
}
|
|
|
|
} // namespace Kernel
|