Add ability to Register a TeardownCallback to notify release of L0 resources

[nrspruit]

This pull request introduces a new teardown callback mechanism for the Level Zero loader, enabling applications to register and handle callbacks during the loader teardown process. It also removes the old stability check mechanism and replaces it with a more robust teardown notification system. Below are the most important changes grouped by themes:

Teardown Callback Mechanism:

• Added a new API function, zelRegisterTeardownCallback, allowing applications to register teardown callbacks. This includes defining the function prototype and its implementation in both ze_loader.h and ze_lib.cpp (zelRegisterTeardownCallback) [1] [2].
• Introduced new data structures in ze_lib.h, such as teardownCallbacks (a map) and teardownCallbacksCount (an atomic counter), to manage registered callbacks and their indices (teardownCallbacks, teardownCallbacksCount).

Loader Teardown Handling:

• Implemented logic in the context_t destructor to invoke registered teardown callbacks and clear the callback registry during loader teardown (teardownCallbacks.clear()) [1] [2].
• Added staticLoaderTeardownCallback and applicationTeardownCallback functions to handle loader teardown events and remove callbacks from the registry (staticLoaderTeardownCallback, applicationTeardownCallback).

Initialization and Registration:

• Updated ze_lib context initialization to dynamically load the zelRegisterTeardownCallback function and register the static loader callback if available (zelRegisterTeardownCallback).

Stability Check Removal:

• Removed the old stability check mechanism, including the stabilityCheck function and related code, replacing it with the new teardown callback system [1] [2].

Debugging and Logging Enhancements:

• Enhanced debug tracing to log messages when teardown callbacks are registered, invoked, or when the loader enters a teardown state (debug_trace_message) [1] [2].

[Copilot]

Pull Request Overview

This pull request introduces a new teardown callback mechanism in the Level Zero loader that enables applications to register callbacks during loader teardown. The key changes include:

• Implementation of the new API function zelRegisterTeardownCallback and its declaration in both the header and source files.
• Introduction of new data structures (atomic counter, map, mutex) in the context for managing registered callbacks.
• Updates to the loader teardown handling logic in the context destructor and in the zelCheckIsLoaderInTearDown function.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
source/lib/ze_lib.h	Added new data structures and included ze_loader.h for teardown callback support.
source/lib/ze_lib.cpp	Implemented callback invocation logic in the context destructor, defined static and application teardown callbacks, and updated registration and teardown state checks.
include/loader/ze_loader.h	Declared the new API functions and callback type definitions for teardown handling.

Comments suppressed due to low confidence (1)

source/lib/ze_lib.cpp:73

• Before invoking loaderTeardownCallback, consider adding an explicit null-check to ensure that the callback pointer is valid to prevent potential null pointer dereference issues.

if (loaderTeardownRegistrationEnabled && !loaderTeardownCallbackReceived) { loaderTeardownCallback(loaderTeardownCallbackIndex); }