[llvm] [Offload] Properly guard modifications to the RPC device array (PR #126790)

[Joseph Huber via llvm-commits]

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@@ -128,6 +128,7 @@ void RPCServerTy::ServerThread::run() {
     Lock.unlock();
     while (NumUsers.load(std::memory_order_relaxed) > 0 &&
            Running.load(std::memory_order_relaxed)) {
+      std::lock_guard<decltype(Mutex)> Lock(BufferMutex);
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jhuber6 wrote:

Every time we do a full scan of all the ports, so very often but I don't think there's a way to avoid that overhead.

https://github.com/llvm/llvm-project/pull/126790