active_context
old_active_cntx = atomic_long_read(&per_cpu(active_context, cpu));
atomic_long_cmpxchg_relaxed(&per_cpu(active_context, cpu),
atomic_long_set(&per_cpu(active_context, cpu), cntx);
static DEFINE_PER_CPU(atomic_long_t, active_context);
cntx = atomic_long_xchg_relaxed(&per_cpu(active_context, i), 0);
cap->rq = active_context(engine, active_ccid(engine));
rq = active_context(engine, engine->execlists.reset_ccid);