CHN_LINK
SLIST_FOREACH(x, CHN_HEAD(y, z), CHN_LINK(z))
SLIST_FOREACH_MUTABLE(w, CHN_HEAD(x, z), CHN_LINK(z), y)
SLIST_INSERT_HEAD(CHN_HEAD(x, z), y, CHN_LINK(z))
SLIST_INSERT_AFTER(x, y, CHN_LINK(z))
SLIST_REMOVE(CHN_HEAD(x, z), y, pcm_channel, CHN_LINK(z))