Ensure explicit multidriver teardown during context destroy

- When multiple drivers are present, delayed init did not always update
  the handles in the alldrivers such that the drivers were unloaded at
teardown. To fix this, the loader now creates a unique list of driver
library handles opened during the process that need to be released
during context destruction.
- Unit tests added to ensure this functionality continues to operate
  correctly.

Signed-off-by: Neil R. Spruit <[email protected]>

Author: nrspruit

source/loader/ze_loader.cpp

@@ -1,6 +1,6 @@
 /*
  *
- * Copyright (C) 2019-2025 Intel Corporation
+ * Copyright (C) 2019-2026 Intel Corporation
  *
  * SPDX-License-Identifier: MIT
  *
@@ -9,6 +9,7 @@
 
 #include "driver_discovery.h"
 #include <iostream>
+#include <set>
 
 #ifdef __linux__
 #include <unistd.h>
@@ -824,18 +825,36 @@ namespace loader
             }
         }
 
-        for( auto& drv : allDrivers )
-        {
+        // Collect all unique driver handles from allDrivers, zeDrivers, and zesDrivers
+        // to ensure we free each library exactly once, avoiding double-free issues
+        std::set<HMODULE> uniqueHandles;
+        for (const auto& drv : allDrivers) {
             if (drv.handle) {
-                auto free_result = FREE_DRIVER_LIBRARY( drv.handle );
-                auto failure = FREE_DRIVER_LIBRARY_FAILURE_CHECK(free_result);
-                if (debugTraceEnabled && failure) {
-                    GET_LIBRARY_ERROR(freeLibraryErrorValue);
-                    if (!freeLibraryErrorValue.empty()) {
-                        std::string errorMessage = "Free Library Failed for " + drv.name + " With ";
-                        debug_trace_message(errorMessage, freeLibraryErrorValue);
-                        freeLibraryErrorValue.clear();
-                    }
+                uniqueHandles.insert(drv.handle);
+            }
+        }
+        for (const auto& drv : zeDrivers) {
+            if (drv.handle) {
+                uniqueHandles.insert(drv.handle);
+            }
+        }
+        for (const auto& drv : zesDrivers) {
+            if (drv.handle) {
+                uniqueHandles.insert(drv.handle);
+            }
+        }
+
+        // Free each unique driver library exactly once
+        for (auto handle : uniqueHandles)
+        {
+            auto free_result = FREE_DRIVER_LIBRARY( handle );
+            auto failure = FREE_DRIVER_LIBRARY_FAILURE_CHECK(free_result);
+            if (debugTraceEnabled && failure) {
+                GET_LIBRARY_ERROR(freeLibraryErrorValue);
+                if (!freeLibraryErrorValue.empty()) {
+                    std::string errorMessage = "Free Library Failed With ";
+                    debug_trace_message(errorMessage, freeLibraryErrorValue);
+                    freeLibraryErrorValue.clear();
                 }
             }
         }

test/CMakeLists.txt

@@ -9,10 +9,13 @@ add_executable(
   loader_tracing_layer.cpp
 )
 
-# Only include driver_ordering_unit_tests for static builds or non-Windows platforms
-# as it requires internal loader symbols that are not exported in Windows DLLs
+# Only include driver_ordering_unit_tests and driver_teardown_unit_tests for static builds or non-Windows platforms
+# as they require internal loader symbols that are not exported in Windows DLLs
 if(BUILD_STATIC OR NOT WIN32)
-  target_sources(tests PRIVATE driver_ordering_unit_tests.cpp)
+  target_sources(tests PRIVATE
+    driver_ordering_unit_tests.cpp
+    driver_teardown_unit_tests.cpp
+  )
 endif()
 
 # For builds on non-Windows platforms, include init_driver_unit_tests
@@ -745,7 +748,28 @@ set_property(TEST driver_ordering_trim_function PROPERTY ENVIRONMENT "ZE_ENABLE_
 
 add_test(NAME driver_ordering_parse_driver_order COMMAND tests --gtest_filter=DriverOrderingHelperFunctionsTest.ParseDriverOrder_*)
 set_property(TEST driver_ordering_parse_driver_order PROPERTY ENVIRONMENT "ZE_ENABLE_LOADER_DEBUG_TRACE=1;ZE_ENABLE_NULL_DRIVER=1")
+# Driver Teardown Unit Tests
+add_test(NAME driver_teardown_unit_tests COMMAND tests --gtest_filter=DriverTeardownUnitTest.*)
+set_property(TEST driver_teardown_unit_tests PROPERTY ENVIRONMENT "ZE_ENABLE_LOADER_DEBUG_TRACE=1;ZE_ENABLE_NULL_DRIVER=1")
+
+# Individual Driver Teardown Unit Tests for better granular reporting
+add_test(NAME driver_teardown_basic_collection COMMAND tests --gtest_filter=DriverTeardownUnitTest.NoDrivers_*:DriverTeardownUnitTest.AllNullHandles_*:DriverTeardownUnitTest.SingleDriverInAllDrivers_*:DriverTeardownUnitTest.MultipleUniqueHandlesInAllDrivers_*)
+set_property(TEST driver_teardown_basic_collection PROPERTY ENVIRONMENT "ZE_ENABLE_LOADER_DEBUG_TRACE=1;ZE_ENABLE_NULL_DRIVER=1")
+
+add_test(NAME driver_teardown_duplicate_handles COMMAND tests --gtest_filter=DriverTeardownUnitTest.SameHandleInAllThreeVectors_*:DriverTeardownUnitTest.MultipleDuplicateHandlesAcrossVectors_*:DriverTeardownUnitTest.SameHandleInZeAndZesOnly_*)
+set_property(TEST driver_teardown_duplicate_handles PROPERTY ENVIRONMENT "ZE_ENABLE_LOADER_DEBUG_TRACE=1;ZE_ENABLE_NULL_DRIVER=1")
+
+add_test(NAME driver_teardown_handle_distribution COMMAND tests --gtest_filter=DriverTeardownUnitTest.OnlyZeDriversHaveHandles_*:DriverTeardownUnitTest.OnlyZesDriversHaveHandles_*:DriverTeardownUnitTest.DifferentHandlesInEachVector_*)
+set_property(TEST driver_teardown_handle_distribution PROPERTY ENVIRONMENT "ZE_ENABLE_LOADER_DEBUG_TRACE=1;ZE_ENABLE_NULL_DRIVER=1")
+
+add_test(NAME driver_teardown_realistic_scenarios COMMAND tests --gtest_filter=DriverTeardownUnitTest.SingleDriverScenario_*:DriverTeardownUnitTest.MultipleDriversScenario_*:DriverTeardownUnitTest.PartialInitialization_*:DriverTeardownUnitTest.DifferentDriversInitializedInZeVsZes_*)
+set_property(TEST driver_teardown_realistic_scenarios PROPERTY ENVIRONMENT "ZE_ENABLE_LOADER_DEBUG_TRACE=1;ZE_ENABLE_NULL_DRIVER=1")
+
+add_test(NAME driver_teardown_edge_cases COMMAND tests --gtest_filter=DriverTeardownUnitTest.MixedNullAndValidHandles_*:DriverTeardownUnitTest.VectorSizeMismatch_*:DriverTeardownUnitTest.LargeNumberOfDrivers_*:DriverTeardownUnitTest.CustomDriverScenario_*)
+set_property(TEST driver_teardown_edge_cases PROPERTY ENVIRONMENT "ZE_ENABLE_LOADER_DEBUG_TRACE=1;ZE_ENABLE_NULL_DRIVER=1")
 
+add_test(NAME driver_teardown_driver_types COMMAND tests --gtest_filter=DriverTeardownUnitTest.MixedDriverTypes_*:DriverTeardownUnitTest.ComplexRealWorldScenario_*)
+set_property(TEST driver_teardown_driver_types PROPERTY ENVIRONMENT "ZE_ENABLE_LOADER_DEBUG_TRACE=1;ZE_ENABLE_NULL_DRIVER=1")
 # Init Driver Unit Tests
 add_test(NAME init_driver_unit_tests COMMAND tests --gtest_filter=InitDriverUnitTest.*)
 if (MSVC)