Explicitly specify USMFree as a non-blocking operation.

Also update CL adapter to reflect this.

include/ur_api.h

@@ -3645,6 +3645,13 @@ urUSMSharedAlloc(
 ///////////////////////////////////////////////////////////////////////////////
 /// @brief Free the USM memory object
 ///
+/// @details
+///     - Note that implementations are not obliged to wait for previously
+///       enqueued operations that may be using `hMem` to finish before freeing
+///       `hMem`.
+///     - Care should be taken to properly synchronize calling this entry point
+///       with any prior uses of `hMem`, especially kernel executions.
+///
 /// @returns
 ///     - ::UR_RESULT_SUCCESS
 ///     - ::UR_RESULT_ERROR_UNINITIALIZED

scripts/core/usm.yml

@@ -361,6 +361,9 @@ desc: "Free the USM memory object"
 class: $xUSM
 name: Free
 ordinal: "0"
+details:
+  - "Note that implementations are not obliged to wait for previously enqueued operations that may be using `hMem` to finish before freeing `hMem`."
+  - "Care should be taken to properly synchronize calling this entry point with any prior uses of `hMem`, especially kernel executions."
 params:
     - type: $x_context_handle_t
       name: hContext

source/adapters/opencl/common.hpp

@@ -186,7 +186,7 @@ namespace cl_ext {
 CONSTFIX char HostMemAllocName[] = "clHostMemAllocINTEL";
 CONSTFIX char DeviceMemAllocName[] = "clDeviceMemAllocINTEL";
 CONSTFIX char SharedMemAllocName[] = "clSharedMemAllocINTEL";
-CONSTFIX char MemBlockingFreeName[] = "clMemBlockingFreeINTEL";
+CONSTFIX char MemFreeName[] = "clMemFreeINTEL";
 CONSTFIX char CreateBufferWithPropertiesName[] =
     "clCreateBufferWithPropertiesINTEL";
 CONSTFIX char SetKernelArgMemPointerName[] = "clSetKernelArgMemPointerINTEL";

source/adapters/opencl/extension_functions.def

@@ -4,7 +4,7 @@ CL_EXTENSION_FUNC(clSharedMemAllocINTEL)
 CL_EXTENSION_FUNC(clGetDeviceFunctionPointer)
 CL_EXTENSION_FUNC(clGetDeviceGlobalVariablePointer)
 CL_EXTENSION_FUNC(clCreateBufferWithPropertiesINTEL)
-CL_EXTENSION_FUNC(clMemBlockingFreeINTEL)
+CL_EXTENSION_FUNC(clMemFreeINTEL)
 CL_EXTENSION_FUNC(clSetKernelArgMemPointerINTEL)
 CL_EXTENSION_FUNC(clEnqueueMemFillINTEL)
 CL_EXTENSION_FUNC(clEnqueueMemcpyINTEL)

source/adapters/opencl/usm.cpp

@@ -239,16 +239,13 @@ urUSMSharedAlloc(ur_context_handle_t hContext, ur_device_handle_t hDevice,
 
 UR_APIEXPORT ur_result_t UR_APICALL urUSMFree(ur_context_handle_t hContext,
                                               void *pMem) {
-
-  // Use a blocking free to avoid issues with indirect access from kernels that
-  // might be still running.
-  clMemBlockingFreeINTEL_fn FuncPtr = nullptr;
+  clMemFreeINTEL_fn FuncPtr = nullptr;
 
   cl_context CLContext = cl_adapter::cast<cl_context>(hContext);
   ur_result_t RetVal = UR_RESULT_ERROR_INVALID_OPERATION;
-  RetVal = cl_ext::getExtFuncFromContext<clMemBlockingFreeINTEL_fn>(
-      CLContext, cl_ext::ExtFuncPtrCache->clMemBlockingFreeINTELCache,
-      cl_ext::MemBlockingFreeName, &FuncPtr);
+  RetVal = cl_ext::getExtFuncFromContext<clMemFreeINTEL_fn>(
+      CLContext, cl_ext::ExtFuncPtrCache->clMemFreeINTELCache,
+      cl_ext::MemFreeName, &FuncPtr);
 
   if (FuncPtr) {
     RetVal = mapCLErrorToUR(FuncPtr(CLContext, pMem));
@@ -299,10 +296,10 @@ UR_APIEXPORT ur_result_t UR_APICALL urEnqueueUSMFill(
       CLContext, cl_ext::ExtFuncPtrCache->clEnqueueMemcpyINTELCache,
       cl_ext::EnqueueMemcpyName, &USMMemcpy));
 
-  clMemBlockingFreeINTEL_fn USMFree = nullptr;
-  UR_RETURN_ON_FAILURE(cl_ext::getExtFuncFromContext<clMemBlockingFreeINTEL_fn>(
-      CLContext, cl_ext::ExtFuncPtrCache->clMemBlockingFreeINTELCache,
-      cl_ext::MemBlockingFreeName, &USMFree));
+  clMemFreeINTEL_fn USMFree = nullptr;
+  UR_RETURN_ON_FAILURE(cl_ext::getExtFuncFromContext<clMemFreeINTEL_fn>(
+      CLContext, cl_ext::ExtFuncPtrCache->clMemFreeINTELCache,
+      cl_ext::MemFreeName, &USMFree));
 
   cl_int ClErr = CL_SUCCESS;
   auto HostBuffer =
@@ -369,10 +366,10 @@ UR_APIEXPORT ur_result_t UR_APICALL urEnqueueUSMMemcpy(
       CLContext, cl_ext::ExtFuncPtrCache->clEnqueueMemcpyINTELCache,
       cl_ext::EnqueueMemcpyName, &USMMemcpy));
 
-  clMemBlockingFreeINTEL_fn USMFree = nullptr;
-  UR_RETURN_ON_FAILURE(cl_ext::getExtFuncFromContext<clMemBlockingFreeINTEL_fn>(
-      CLContext, cl_ext::ExtFuncPtrCache->clMemBlockingFreeINTELCache,
-      cl_ext::MemBlockingFreeName, &USMFree));
+  clMemFreeINTEL_fn USMFree = nullptr;
+  UR_RETURN_ON_FAILURE(cl_ext::getExtFuncFromContext<clMemFreeINTEL_fn>(
+      CLContext, cl_ext::ExtFuncPtrCache->clMemFreeINTELCache,
+      cl_ext::MemFreeName, &USMFree));
 
   // Check if the two allocations are DEVICE allocations from different
   // devices, if they are we need to do the copy indirectly via a host

source/loader/ur_libapi.cpp

@@ -2400,6 +2400,13 @@ ur_result_t UR_APICALL urUSMSharedAlloc(
 ///////////////////////////////////////////////////////////////////////////////
 /// @brief Free the USM memory object
 ///
+/// @details
+///     - Note that implementations are not obliged to wait for previously
+///       enqueued operations that may be using `hMem` to finish before freeing
+///       `hMem`.
+///     - Care should be taken to properly synchronize calling this entry point
+///       with any prior uses of `hMem`, especially kernel executions.
+///
 /// @returns
 ///     - ::UR_RESULT_SUCCESS
 ///     - ::UR_RESULT_ERROR_UNINITIALIZED

source/ur_api.cpp

@@ -2076,6 +2076,13 @@ ur_result_t UR_APICALL urUSMSharedAlloc(
 ///////////////////////////////////////////////////////////////////////////////
 /// @brief Free the USM memory object
 ///
+/// @details
+///     - Note that implementations are not obliged to wait for previously
+///       enqueued operations that may be using `hMem` to finish before freeing
+///       `hMem`.
+///     - Care should be taken to properly synchronize calling this entry point
+///       with any prior uses of `hMem`, especially kernel executions.
+///
 /// @returns
 ///     - ::UR_RESULT_SUCCESS
 ///     - ::UR_RESULT_ERROR_UNINITIALIZED