loopback_setup
dev = alloc_netdev(0, "lo", NET_NAME_PREDICTABLE, loopback_setup);
struct loopback_setup setup[MAX_PCM_SUBSTREAMS][2];
struct loopback_setup *setup;
static inline struct loopback_setup *get_setup(struct loopback_pcm *dpcm)
struct loopback_setup *setup;