What are lock-free programming techniques in embedded systems?

Lock-free programming avoids mutexes using atomic operations, preventing priority inversion and deadlocks. Key concepts: Atomic operations: Read-modify-write that cannot be interrupted (load-exclusive/store-exclusive on ARM). Compare-and-swap (CAS): Atomically update if current value matches expected. Memory barriers: Ensure memory operation ordering across cores/compiler. Common patterns: Lock-free queue (single-producer single-consumer): Head and tail pointers updated atomically; no locks needed. Lock-free stack: CAS to update top pointer. Seqlock: Sequence counter for read-mostly data. RCU (Read-Copy-Update): Readers lock-free, writers copy-modify-replace. Challenges: ABA problem (value changes and changes back). Memory ordering complexity (acquire/release semantics). Harder to reason about correctness. Platform-specific implementations. Tools: C11/C++11 atomics (<stdatomic.h>), compiler intrinsics. Use cases: ISR to task communication, high-performance logging, low-latency data paths.