SIMPLEQ_FIRST
pbuf = SIMPLEQ_FIRST(&skdev->waitqueue);
for ((var) = SIMPLEQ_FIRST((head)); \
((var) != SIMPLEQ_END(head) ? (var) : SIMPLEQ_FIRST((head)));\
for ((var) = SIMPLEQ_FIRST((head)); \
((var) != SIMPLEQ_END(head) ? (var) : SIMPLEQ_FIRST((head)));\
SIMPLEQ_FIRST((head)) = NULL; \
(head)->sqh_last = &SIMPLEQ_FIRST((head)); \
if ((SIMPLEQ_NEXT((elm), field) = SIMPLEQ_FIRST((head))) == NULL)\
SIMPLEQ_FIRST((head)) = (elm); \
if ((SIMPLEQ_FIRST((head)) = \
SIMPLEQ_NEXT(SIMPLEQ_FIRST((head)), field)) == NULL) \
(head)->sqh_last = &SIMPLEQ_FIRST((head)); \
if (SIMPLEQ_FIRST((head)) == (elm)) { \
QUEUE_TYPEOF(type) *curelm = SIMPLEQ_FIRST((head)); \