Just Verification of Mutual Exclusion Algorithms

TL;DR

This paper employs model checking to verify the correctness of various mutual exclusion algorithms, considering different assumptions about shared register communication and using justness as a completeness criterion.

Contribution

It introduces a verification approach for mutual exclusion algorithms that accounts for atomic and non-atomic shared registers using justness, and suggests improvements based on counterexamples.

Findings

Several algorithms violate correctness properties under certain assumptions.

Using justness helps eliminate spurious counterexamples in verification.

Proposed improvements enhance algorithm correctness.

Abstract

We verify the correctness of a variety of mutual exclusion algorithms through model checking. We look at algorithms where communication is via shared read/write registers, where those registers can be atomic or non-atomic. For the verification of liveness properties, it is necessary to assume a completeness criterion to eliminate spurious counterexamples. We use justness as completeness criterion. Justness depends on a concurrency relation; we consider several such relations, modelling different assumptions on the working of the shared registers. We present executions demonstrating the violation of correctness properties by several algorithms, and in some cases suggest improvements.