[Offload] Make olLaunchKernel test thread safe

offload/include/Shared/APITypes.h

@@ -21,6 +21,7 @@
 
 #include <cstddef>
 #include <cstdint>
+#include <mutex>
 
 extern "C" {
 
@@ -75,6 +76,11 @@ struct __tgt_async_info {
   /// should be freed after finalization.
   llvm::SmallVector<void *, 2> AssociatedAllocations;
 
+  /// Mutex to guard access to AssociatedAllocations and the Queue.
+  /// This is only used for liboffload and should be ignored in libomptarget
+  /// code.
+  std::mutex Mutex;
+
   /// The kernel launch environment used to issue a kernel. Stored here to
   /// ensure it is a valid location while the transfer to the device is
   /// happening.

offload/liboffload/src/OffloadImpl.cpp

@@ -206,7 +206,7 @@ Error initPlugins(OffloadContext &Context) {
 }
 
 Error olInit_impl() {
-  std::lock_guard<std::mutex> Lock{OffloadContextValMutex};
+  std::lock_guard<std::mutex> Lock(OffloadContextValMutex);
 
   if (isOffloadInitialized()) {
     OffloadContext::get().RefCount++;
@@ -224,7 +224,7 @@ Error olInit_impl() {
 }
 
 Error olShutDown_impl() {
-  std::lock_guard<std::mutex> Lock{OffloadContextValMutex};
+  std::lock_guard<std::mutex> Lock(OffloadContextValMutex);
 
   if (--OffloadContext::get().RefCount != 0)
     return Error::success();
@@ -487,16 +487,12 @@ Error olSyncQueue_impl(ol_queue_handle_t Queue) {
   // Host plugin doesn't have a queue set so it's not safe to call synchronize
   // on it, but we have nothing to synchronize in that situation anyway.
   if (Queue->AsyncInfo->Queue) {
-    if (auto Err = Queue->Device->Device->synchronize(Queue->AsyncInfo))
+    // We don't need to release the queue and we would like the ability for
+    // other offload threads to submit work concurrently, so pass "false" here.
+    if (auto Err = Queue->Device->Device->synchronize(Queue->AsyncInfo, false))
       return Err;
   }
 
-  // Recreate the stream resource so the queue can be reused
-  // TODO: Would be easier for the synchronization to (optionally) not release
-  // it to begin with.
-  if (auto Res = Queue->Device->Device->initAsyncInfo(&Queue->AsyncInfo))
-    return Res;
-
   return Error::success();
 }
 
@@ -727,7 +723,7 @@ Error olGetSymbol_impl(ol_program_handle_t Program, const char *Name,
                        ol_symbol_kind_t Kind, ol_symbol_handle_t *Symbol) {
   auto &Device = Program->Image->getDevice();
 
-  std::lock_guard<std::mutex> Lock{Program->SymbolListMutex};
+  std::lock_guard<std::mutex> Lock(Program->SymbolListMutex);
 
   switch (Kind) {
   case OL_SYMBOL_KIND_KERNEL: {

offload/libomptarget/interface.cpp

@@ -116,7 +116,7 @@ targetData(ident_t *Loc, int64_t DeviceId, int32_t ArgNum, void **ArgsBase,
            TargetDataFuncPtrTy TargetDataFunction, const char *RegionTypeMsg,
            const char *RegionName) {
   assert(PM && "Runtime not initialized");
-  static_assert(std::is_convertible_v<TargetAsyncInfoTy, AsyncInfoTy>,
+  static_assert(std::is_convertible_v<TargetAsyncInfoTy &, AsyncInfoTy &>,
                 "TargetAsyncInfoTy must be convertible to AsyncInfoTy.");
 
   TIMESCOPE_WITH_DETAILS_AND_IDENT("Runtime: Data Copy",
@@ -311,7 +311,7 @@ static inline int targetKernel(ident_t *Loc, int64_t DeviceId, int32_t NumTeams,
                                int32_t ThreadLimit, void *HostPtr,
                                KernelArgsTy *KernelArgs) {
   assert(PM && "Runtime not initialized");
-  static_assert(std::is_convertible_v<TargetAsyncInfoTy, AsyncInfoTy>,
+  static_assert(std::is_convertible_v<TargetAsyncInfoTy &, AsyncInfoTy &>,
                 "Target AsyncInfoTy must be convertible to AsyncInfoTy.");
   DP("Entering target region for device %" PRId64 " with entry point " DPxMOD
      "\n",

offload/plugins-nextgen/amdgpu/src/rtl.cpp

@@ -2232,16 +2232,11 @@ struct AMDGPUDeviceTy : public GenericDeviceTy, AMDGenericDeviceTy {
   /// Get the stream of the asynchronous info structure or get a new one.
   Error getStream(AsyncInfoWrapperTy &AsyncInfoWrapper,
                   AMDGPUStreamTy *&Stream) {
-    // Get the stream (if any) from the async info.
-    Stream = AsyncInfoWrapper.getQueueAs<AMDGPUStreamTy *>();
-    if (!Stream) {
-      // There was no stream; get an idle one.
-      if (auto Err = AMDGPUStreamManager.getResource(Stream))
-        return Err;
-
-      // Modify the async info's stream.
-      AsyncInfoWrapper.setQueueAs<AMDGPUStreamTy *>(Stream);
-    }
+    auto WrapperStream =
+        AsyncInfoWrapper.getOrInitQueue<AMDGPUStreamTy *>(AMDGPUStreamManager);
+    if (!WrapperStream)
+      return WrapperStream.takeError();
+    Stream = *WrapperStream;
     return Plugin::success();
   }
 
@@ -2296,7 +2291,8 @@ struct AMDGPUDeviceTy : public GenericDeviceTy, AMDGenericDeviceTy {
   }
 
   /// Synchronize current thread with the pending operations on the async info.
-  Error synchronizeImpl(__tgt_async_info &AsyncInfo) override {
+  Error synchronizeImpl(__tgt_async_info &AsyncInfo,
+                        bool ReleaseQueue) override {
     AMDGPUStreamTy *Stream =
         reinterpret_cast<AMDGPUStreamTy *>(AsyncInfo.Queue);
     assert(Stream && "Invalid stream");
@@ -2307,8 +2303,11 @@ 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 (ReleaseQueue) {
+      AsyncInfo.Queue = nullptr;
+      return AMDGPUStreamManager.returnResource(Stream);
+    }
+    return Plugin::success();
   }
 
   /// Query for the completion of the pending operations on the async info.

offload/plugins-nextgen/common/include/PluginInterface.h

@@ -59,6 +59,7 @@ struct GenericPluginTy;
 struct GenericKernelTy;
 struct GenericDeviceTy;
 struct RecordReplayTy;
+template <typename ResourceRef> class GenericDeviceResourceManagerTy;
 
 /// Class that wraps the __tgt_async_info to simply its usage. In case the
 /// object is constructed without a valid __tgt_async_info, the object will use
@@ -93,6 +94,20 @@ struct AsyncInfoWrapperTy {
     AsyncInfoPtr->Queue = Queue;
   }
 
+  /// Get the queue, using the provided resource manager to initialise it if it
+  /// doesn't exist.
+  template <typename Ty, typename RMTy>
+  Expected<Ty>
+  getOrInitQueue(GenericDeviceResourceManagerTy<RMTy> &ResourceManager) {
+    std::lock_guard<std::mutex> Lock(AsyncInfoPtr->Mutex);
+    if (!AsyncInfoPtr->Queue) {
+      if (auto Err = ResourceManager.getResource(
+              *reinterpret_cast<Ty *>(&AsyncInfoPtr->Queue)))
+        return Err;
+    }
+    return getQueueAs<Ty>();
+  }
+
   /// Synchronize with the __tgt_async_info's pending operations if it's the
   /// internal async info. The error associated to the asynchronous operations
   /// issued in this queue must be provided in \p Err. This function will update
@@ -104,6 +119,7 @@ struct AsyncInfoWrapperTy {
   /// Register \p Ptr as an associated allocation that is freed after
   /// finalization.
   void freeAllocationAfterSynchronization(void *Ptr) {
+    std::lock_guard<std::mutex> AllocationGuard{AsyncInfoPtr->Mutex};
     AsyncInfoPtr->AssociatedAllocations.push_back(Ptr);
   }
 
@@ -793,9 +809,12 @@ struct GenericDeviceTy : public DeviceAllocatorTy {
   Error setupRPCServer(GenericPluginTy &Plugin, DeviceImageTy &Image);
 
   /// Synchronize the current thread with the pending operations on the
-  /// __tgt_async_info structure.
-  Error synchronize(__tgt_async_info *AsyncInfo);
-  virtual Error synchronizeImpl(__tgt_async_info &AsyncInfo) = 0;
+  /// __tgt_async_info structure. If ReleaseQueue is false, then the
+  // underlying queue will not be released. In this case, additional
+  // work may be submitted to the queue whilst a synchronize is running.
+  Error synchronize(__tgt_async_info *AsyncInfo, bool ReleaseQueue = true);
+  virtual Error synchronizeImpl(__tgt_async_info &AsyncInfo,
+                                bool ReleaseQueue) = 0;
 
   /// Invokes any global constructors on the device if present and is required
   /// by the target.

offload/plugins-nextgen/common/src/PluginInterface.cpp

@@ -1329,18 +1329,25 @@ Error PinnedAllocationMapTy::unlockUnmappedHostBuffer(void *HstPtr) {
   return eraseEntry(*Entry);
 }
 
-Error GenericDeviceTy::synchronize(__tgt_async_info *AsyncInfo) {
-  if (!AsyncInfo || !AsyncInfo->Queue)
-    return Plugin::error(ErrorCode::INVALID_ARGUMENT,
-                         "invalid async info queue");
+Error GenericDeviceTy::synchronize(__tgt_async_info *AsyncInfo,
+                                   bool ReleaseQueue) {
+  SmallVector<void *, 2> AllocsToDelete{};
+  {
+    std::lock_guard<std::mutex> AllocationGuard{AsyncInfo->Mutex};
 
-  if (auto Err = synchronizeImpl(*AsyncInfo))
-    return Err;
+    if (!AsyncInfo || !AsyncInfo->Queue)
+      return Plugin::error(ErrorCode::INVALID_ARGUMENT,
+                           "invalid async info queue");
+
+    if (auto Err = synchronizeImpl(*AsyncInfo, ReleaseQueue))
+      return Err;
+
+    std::swap(AllocsToDelete, AsyncInfo->AssociatedAllocations);
+  }
 
-  for (auto *Ptr : AsyncInfo->AssociatedAllocations)
+  for (auto *Ptr : AllocsToDelete)
     if (auto Err = dataDelete(Ptr, TargetAllocTy::TARGET_ALLOC_DEVICE))
       return Err;
-  AsyncInfo->AssociatedAllocations.clear();
 
   return Plugin::success();
 }

offload/plugins-nextgen/cuda/src/rtl.cpp

@@ -522,16 +522,11 @@ struct CUDADeviceTy : public GenericDeviceTy {
 
   /// Get the stream of the asynchronous info structure or get a new one.
   Error getStream(AsyncInfoWrapperTy &AsyncInfoWrapper, CUstream &Stream) {
-    // Get the stream (if any) from the async info.
-    Stream = AsyncInfoWrapper.getQueueAs<CUstream>();
-    if (!Stream) {
-      // There was no stream; get an idle one.
-      if (auto Err = CUDAStreamManager.getResource(Stream))
-        return Err;
-
-      // Modify the async info's stream.
-      AsyncInfoWrapper.setQueueAs<CUstream>(Stream);
-    }
+    auto WrapperStream =
+        AsyncInfoWrapper.getOrInitQueue<CUstream>(CUDAStreamManager);
+    if (!WrapperStream)
+      return WrapperStream.takeError();
+    Stream = *WrapperStream;
     return Plugin::success();
   }
 
@@ -642,17 +637,20 @@ struct CUDADeviceTy : public GenericDeviceTy {
   }
 
   /// Synchronize current thread with the pending operations on the async info.
-  Error synchronizeImpl(__tgt_async_info &AsyncInfo) override {
+  Error synchronizeImpl(__tgt_async_info &AsyncInfo,
+                        bool ReleaseQueue) override {
     CUstream Stream = reinterpret_cast<CUstream>(AsyncInfo.Queue);
     CUresult Res;
     Res = cuStreamSynchronize(Stream);
 
-    // 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;
-    if (auto Err = CUDAStreamManager.returnResource(Stream))
-      return Err;
+    // Once the stream is synchronized and we want to release the queue, return
+    // it to stream pool and reset AsyncInfo. This is to make sure the
+    // synchronization only works for its own tasks.
+    if (ReleaseQueue) {
+      AsyncInfo.Queue = nullptr;
+      if (auto Err = CUDAStreamManager.returnResource(Stream))
+        return Err;
+    }
 
     return Plugin::check(Res, "error in cuStreamSynchronize: %s");
   }

offload/plugins-nextgen/host/src/rtl.cpp

@@ -297,7 +297,8 @@ struct GenELF64DeviceTy : public GenericDeviceTy {
 
   /// All functions are already synchronous. No need to do anything on this
   /// synchronization function.
-  Error synchronizeImpl(__tgt_async_info &AsyncInfo) override {
+  Error synchronizeImpl(__tgt_async_info &AsyncInfo,
+                        bool ReleaseQueue) override {
     return Plugin::success();
   }
 

offload/unittests/OffloadAPI/common/Fixtures.hpp

@@ -9,6 +9,7 @@
 #include <OffloadAPI.h>
 #include <OffloadPrint.hpp>
 #include <gtest/gtest.h>
+#include <thread>
 
 #include "Environment.hpp"
 
@@ -57,6 +58,23 @@ inline std::string SanitizeString(const std::string &Str) {
   return NewStr;
 }
 
+template <typename Fn> inline void threadify(Fn body) {
+  std::vector<std::thread> Threads;
+  for (size_t I = 0; I < 20; I++) {
+    Threads.emplace_back(
+        [&body](size_t I) {
+          std::string ScopeMsg{"Thread #"};
+          ScopeMsg.append(std::to_string(I));
+          SCOPED_TRACE(ScopeMsg);
+          body(I);
+        },
+        I);
+  }
+  for (auto &T : Threads) {
+    T.join();
+  }
+}
+
 struct OffloadTest : ::testing::Test {
   ol_device_handle_t Host = TestEnvironment::getHostDevice();
 };

offload/unittests/OffloadAPI/kernel/olLaunchKernel.cpp

@@ -104,6 +104,29 @@ TEST_P(olLaunchKernelFooTest, Success) {
   ASSERT_SUCCESS(olMemFree(Mem));
 }
 
+TEST_P(olLaunchKernelFooTest, SuccessThreaded) {
+  threadify([&](size_t) {
+    void *Mem;
+    ASSERT_SUCCESS(olMemAlloc(Device, OL_ALLOC_TYPE_MANAGED,
+                              LaunchArgs.GroupSize.x * sizeof(uint32_t), &Mem));
+    struct {
+      void *Mem;
+    } Args{Mem};
+
+    ASSERT_SUCCESS(olLaunchKernel(Queue, Device, Kernel, &Args, sizeof(Args),
+                                  &LaunchArgs, nullptr));
+
+    ASSERT_SUCCESS(olWaitQueue(Queue));
+
+    uint32_t *Data = (uint32_t *)Mem;
+    for (uint32_t i = 0; i < 64; i++) {
+      ASSERT_EQ(Data[i], i);
+    }
+
+    ASSERT_SUCCESS(olMemFree(Mem));
+  });
+}
+
 TEST_P(olLaunchKernelNoArgsTest, Success) {
   ASSERT_SUCCESS(
       olLaunchKernel(Queue, Device, Kernel, nullptr, 0, &LaunchArgs));