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https://github.com/RGBCube/serenity
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AK: Add Atomic.h
Use gcc built-in atomics
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parent
2530378f59
commit
b0773a8ea6
6 changed files with 606 additions and 53 deletions
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@ -9,15 +9,15 @@ void Lock::lock()
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hang();
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}
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for (;;) {
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if (CAS(&m_lock, 1, 0) == 0) {
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bool expected = false;
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if (m_lock.compare_exchange_strong(expected, true, AK::memory_order_acq_rel)) {
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if (!m_holder || m_holder == current) {
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m_holder = current;
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++m_level;
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memory_barrier();
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m_lock = 0;
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m_lock.store(false, AK::memory_order_release);
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return;
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}
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m_lock = 0;
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m_lock.store(false, AK::memory_order_release);
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}
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Scheduler::donate_to(m_holder, m_name);
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}
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@ -26,18 +26,17 @@ void Lock::lock()
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void Lock::unlock()
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{
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for (;;) {
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if (CAS(&m_lock, 1, 0) == 0) {
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bool expected = false;
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if (m_lock.compare_exchange_strong(expected, true, AK::memory_order_acq_rel)) {
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ASSERT(m_holder == current);
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ASSERT(m_level);
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--m_level;
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if (m_level) {
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memory_barrier();
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m_lock = 0;
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m_lock.store(false, AK::memory_order_release);
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return;
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}
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m_holder = nullptr;
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memory_barrier();
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m_lock = 0;
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m_lock.store(false, AK::memory_order_release);
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return;
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}
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Scheduler::donate_to(m_holder, m_name);
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@ -47,25 +46,24 @@ void Lock::unlock()
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bool Lock::unlock_if_locked()
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{
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for (;;) {
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if (CAS(&m_lock, 1, 0) == 0) {
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bool expected = false;
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if (m_lock.compare_exchange_strong(expected, true, AK::memory_order_acq_rel)) {
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if (m_level == 0) {
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m_lock = 0;
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m_lock.store(false, AK::memory_order_release);
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return false;
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}
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if (m_holder != current) {
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m_lock = 0;
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m_lock.store(false, AK::memory_order_release);
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return false;
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}
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ASSERT(m_level);
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--m_level;
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if (m_level) {
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memory_barrier();
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m_lock = 0;
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m_lock.store(false, AK::memory_order_release);
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return false;
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}
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m_holder = nullptr;
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memory_barrier();
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m_lock = 0;
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m_lock.store(false, AK::memory_order_release);
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return true;
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}
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}
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@ -2,6 +2,7 @@
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#include <AK/Assertions.h>
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#include <AK/Types.h>
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#include <AK/Atomic.h>
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#include <Kernel/Arch/i386/CPU.h>
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#include <Kernel/KSyms.h>
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#include <Kernel/Scheduler.h>
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@ -9,17 +10,6 @@
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class Thread;
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extern Thread* current;
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static inline u32 CAS(volatile u32* mem, u32 newval, u32 oldval)
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{
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u32 ret;
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asm volatile(
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"cmpxchgl %2, %1"
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: "=a"(ret), "+m"(*mem)
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: "r"(newval), "0"(oldval)
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: "cc", "memory");
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return ret;
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}
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class Lock {
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public:
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Lock(const char* name = nullptr)
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@ -35,7 +25,7 @@ public:
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const char* name() const { return m_name; }
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private:
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volatile u32 m_lock { 0 };
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Atomic<bool> m_lock { false };
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u32 m_level { 0 };
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Thread* m_holder { nullptr };
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const char* m_name { nullptr };
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