SIMPLE_RB_READY
if (cmpxchg(&cpu_buffer->status, SIMPLE_RB_READY, SIMPLE_RB_WRITING) != SIMPLE_RB_READY)
smp_store_release(&cpu_buffer->status, SIMPLE_RB_READY);
return cmpxchg(&cpu_buffer->status, SIMPLE_RB_UNAVAILABLE, SIMPLE_RB_READY);
SIMPLE_RB_READY,
if (prev_status == SIMPLE_RB_READY)