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waitQueue.compare_exchange_strong in the true loop can be weak #70636

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Merged
merged 1 commit into from
Jan 9, 2024
+10 −10
Merged

waitQueue.compare_exchange_strong in the true loop can be weak #70636

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20 changes: 10 additions & 10 deletions stdlib/public/Concurrency/TaskGroup.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1779,14 +1779,14 @@ reevaluate_if_taskgroup_has_results:;
// ==== 3) Add to wait queue -------------------------------------------------
assert(assumed.readyTasks(this) == 0);
_swift_tsan_release(static_cast<Job *>(waitingTask));
if (!hasSuspended) {
waitingTask->flagAsSuspendedOnTaskGroup(asAbstract(this));
hasSuspended = true;
}
while (true) {
if (!hasSuspended) {
hasSuspended = true;
waitingTask->flagAsSuspendedOnTaskGroup(asAbstract(this));
}
// Put the waiting task at the beginning of the wait queue.
SWIFT_TASK_GROUP_DEBUG_LOG(this, "WATCH OUT, SET WAITER ONTO waitQueue.head = %p", waitQueue.load(std::memory_order_relaxed));
if (waitQueue.compare_exchange_strong(
if (waitQueue.compare_exchange_weak(
waitHead, waitingTask,
/*success*/ std::memory_order_release,
/*failure*/ std::memory_order_acquire)) {
Expand Down Expand Up @@ -1941,13 +1941,13 @@ void TaskGroupBase::waitAll(SwiftError* bodyError, AsyncTask *waitingTask,

auto waitHead = waitQueue.load(std::memory_order_acquire);
_swift_tsan_release(static_cast<Job *>(waitingTask));
if (!hasSuspended) {
waitingTask->flagAsSuspendedOnTaskGroup(asAbstract(this));
hasSuspended = true;
}
while (true) {
if (!hasSuspended) {
hasSuspended = true;
waitingTask->flagAsSuspendedOnTaskGroup(asAbstract(this));
}
// Put the waiting task at the beginning of the wait queue.
if (waitQueue.compare_exchange_strong(
if (waitQueue.compare_exchange_weak(
waitHead, waitingTask,
/*success*/ std::memory_order_release,
/*failure*/ std::memory_order_acquire)) {
Expand Down