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

[Ross Brunton via llvm-commits]

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@@ -2227,6 +2227,7 @@ struct AMDGPUDeviceTy : public GenericDeviceTy, AMDGenericDeviceTy {
   /// Get the stream of the asynchronous info structure or get a new one.
   Error getStream(AsyncInfoWrapperTy &AsyncInfoWrapper,
                   AMDGPUStreamTy *&Stream) {
+    std::lock_guard<std::mutex> StreamLock{StreamMutex};
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RossBrunton wrote:

Multiple threads can call `getStream`, see that the stream doesn't exist and create a new one. This can result in multiple streams being created in error.

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