Merge pull request #9215 from liamwhite/swordfight

Ensure correctness of atomic store ordering
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Fernando S 2022-11-09 14:50:49 +01:00 committed by GitHub
commit 3161b34ff6
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2 changed files with 9 additions and 3 deletions

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@ -384,7 +384,8 @@ void KScheduler::SwitchThread(KThread* next_thread) {
void KScheduler::ScheduleImpl() {
// First, clear the needs scheduling bool.
m_state.needs_scheduling.store(false, std::memory_order_seq_cst);
m_state.needs_scheduling.store(false, std::memory_order_relaxed);
std::atomic_thread_fence(std::memory_order_seq_cst);
// Load the appropriate thread pointers for scheduling.
KThread* const cur_thread{GetCurrentThreadPointer(kernel)};
@ -400,7 +401,8 @@ void KScheduler::ScheduleImpl() {
// If there aren't, we want to check if the highest priority thread is the same as the current
// thread.
if (highest_priority_thread == cur_thread) {
// If they're the same, then we can just return.
// If they're the same, then we can just issue a memory barrier and return.
std::atomic_thread_fence(std::memory_order_seq_cst);
return;
}
@ -476,7 +478,8 @@ void KScheduler::ScheduleImplFiber() {
// We failed to successfully do the context switch, and need to retry.
// Clear needs_scheduling.
m_state.needs_scheduling.store(false, std::memory_order_seq_cst);
m_state.needs_scheduling.store(false, std::memory_order_relaxed);
std::atomic_thread_fence(std::memory_order_seq_cst);
// Refresh the highest priority thread.
highest_priority_thread = m_state.highest_priority_thread;

View file

@ -60,6 +60,9 @@ public:
// Release an instance of the lock.
if ((--lock_count) == 0) {
// Perform a memory barrier here.
std::atomic_thread_fence(std::memory_order_seq_cst);
// We're no longer going to hold the lock. Take note of what cores need scheduling.
const u64 cores_needing_scheduling =
SchedulerType::UpdateHighestPriorityThreads(kernel);