[llvm] [Offload] Make olLaunchKernel test thread safe (PR #149497)

[Ross Brunton via llvm-commits]

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@@ -2302,8 +2304,11 @@ struct AMDGPUDeviceTy : public GenericDeviceTy, AMDGenericDeviceTy {
     // Once the stream is synchronized, return it to stream pool and reset
     // AsyncInfo. This is to make sure the synchronization only works for its
     // own tasks.
-    AsyncInfo.Queue = nullptr;
-    return AMDGPUStreamManager.returnResource(Stream);
+    if (RemoveQueue) {
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RossBrunton wrote:

Sure, but we still have the race condition. Tweaking the interface here allows us to have the lock cover a smaller section of code.

https://github.com/llvm/llvm-project/pull/149497