TAILQ_END
TAILQ_FIRST(&tmgrp->txn_chain)) != TAILQ_END(&tmgrp->txn_chain))
#define TAILQ_EMPTY(head) ((head)->tqh_first == TAILQ_END(head))
(var) != TAILQ_END(head); \
for ((var) = ((var) != TAILQ_END((head)) ? \
(var) != TAILQ_END(head); \
(var) != TAILQ_END(head) && \
for ((var) = ((var) != TAILQ_END((head)) ? \
(var) != TAILQ_END(head) && \
(var) != TAILQ_END(head); \
for ((var) = ((var) != TAILQ_END((head)) ? \
(var) != TAILQ_END(head); \
(var) != TAILQ_END(head) && \
for ((var) = ((var) != TAILQ_END((head)) ? \
(var) != TAILQ_END(head) && \
TAILQ_FIRST((head)) = TAILQ_END((head)); \