mirror of
https://github.com/Atmosphere-NX/Atmosphere.git
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95 lines
3.7 KiB
C++
95 lines
3.7 KiB
C++
/*
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* Copyright (c) 2018-2020 Atmosphère-NX
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include <mesosphere/kern_common.hpp>
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#include <mesosphere/kern_k_spin_lock.hpp>
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#include <mesosphere/kern_k_current_context.hpp>
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#include <mesosphere/kern_k_scoped_lock.hpp>
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namespace ams::kern {
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class KThread;
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/*
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TODO: C++20
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template<typename T>
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concept KSchedulerLockable = !std::is_reference<T>::value && requires {
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{ T::DisableScheduling() } -> std::same_as<void>;
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{ T::EnableScheduling(std::declval<u64>()) } -> std::same_as<void>;
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{ T::UpdateHighestPriorityThreads() } -> std::convertible_to<u64>;
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};
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*/
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template<typename SchedulerType> /* TODO C++20: requires KSchedulerLockable<SchedulerType> */
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class KAbstractSchedulerLock {
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private:
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KAlignedSpinLock spin_lock;
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s32 lock_count;
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KThread *owner_thread;
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public:
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constexpr ALWAYS_INLINE KAbstractSchedulerLock() : spin_lock(), lock_count(0), owner_thread(nullptr) { MESOSPHERE_ASSERT_THIS(); }
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ALWAYS_INLINE bool IsLockedByCurrentThread() const {
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MESOSPHERE_ASSERT_THIS();
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return this->owner_thread == GetCurrentThreadPointer();
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}
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ALWAYS_INLINE void Lock() {
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MESOSPHERE_ASSERT_THIS();
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if (this->IsLockedByCurrentThread()) {
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/* If we already own the lock, we can just increment the count. */
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MESOSPHERE_ASSERT(this->lock_count > 0);
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this->lock_count++;
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} else {
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/* Otherwise, we want to disable scheduling and acquire the spinlock. */
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SchedulerType::DisableScheduling();
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this->spin_lock.Lock();
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/* For debug, ensure that our state is valid. */
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MESOSPHERE_ASSERT(this->lock_count == 0);
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MESOSPHERE_ASSERT(this->owner_thread == nullptr);
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/* Increment count, take ownership. */
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this->lock_count = 1;
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this->owner_thread = GetCurrentThreadPointer();
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}
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}
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ALWAYS_INLINE void Unlock() {
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MESOSPHERE_ASSERT_THIS();
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MESOSPHERE_ASSERT(this->IsLockedByCurrentThread());
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MESOSPHERE_ASSERT(this->lock_count > 0);
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/* Release an instance of the lock. */
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if ((--this->lock_count) == 0) {
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/* We're no longer going to hold the lock. Take note of what cores need scheduling. */
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const u64 cores_needing_scheduling = SchedulerType::UpdateHighestPriorityThreads();
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/* Note that we no longer hold the lock, and unlock the spinlock. */
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this->owner_thread = nullptr;
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this->spin_lock.Unlock();
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/* Enable scheduling, and perform a rescheduling operation. */
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SchedulerType::EnableScheduling(cores_needing_scheduling);
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}
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}
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};
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}
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