Add user reference for nested maps.

[saxena-anurag]

Fixes #4272

This pull request adds user reference for nested maps (BPF_MAP_TYPE_ARRAY_OF_MAPS, BPF_MAP_TYPE_HASH_OF_MAPS, BPF_MAP_TYPE_PROG_ARRAY), and removes the logic of weak references.

With this change, outer maps maintain both user and total references. User reference corresponds to references taken when the object is pinned or a handle is created. When an object is inserted in the outer map, a reference is taken on the inner object (program or map). Once the user reference of the outer map is 0, the outer map is cleaned up and references to the underlying objects are released.

The PR also removes the refcount logic for the IDs as the weak reference is no longer used.

Note: There is a follow up PR #4684 that should be merged after this PR is merged.

Testing

The PR add news tests to validate the new scenario.

Documentation

No

Installation

No

[Copilot]

Pull Request Overview

This PR adds user reference counting for nested maps (BPF_MAP_TYPE_ARRAY_OF_MAPS, BPF_MAP_TYPE_HASH_OF_MAPS, BPF_MAP_TYPE_PROG_ARRAY) and removes weak reference logic. The change enables outer maps to maintain both user and total references, ensuring proper cleanup when user references reach zero.

• Introduces user reference counting alongside existing reference counting in the object system
• Updates nested maps to take direct references on inner objects instead of using weak ID-based references
• Removes the ID reference counting logic that supported weak references

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
libs/runtime/ebpf_object.h	Adds user reference count field and function signatures for user reference tracking
libs/runtime/ebpf_object.c	Implements user reference counting logic and removes ID-based reference functions
libs/execution_context/ebpf_maps.c	Updates nested maps to use direct object references and adds cleanup logic for user reference zeroing
tests/end_to_end/end_to_end.cpp	Adds comprehensive tests for nested map user reference behavior
tests/api_test/api_test.cpp	Adds API-level tests for user reference functionality and code formatting cleanup

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[Alan-Jowett]

Can we get macros for acquire user reference and acquire kernel reference?