queue: New debug macros for STAILQ

The new STAILQ_ASSERT_EMPTY() macro allows callers to assert that some
STAILQ is empty.  It leverages the new QMD_STAILQ_CHECK_EMPTY() internal
macro.

QMD_STAILQ_CHECK_EMPTY() is a check for empty STAILQ, where heads's
'stqh_last' field must point to the 'stqh_first' one.  Use it in
STAILQ_ASSERT_EMPTY().

QMD_STAILQ_CHECK_TAIL() checks that the tail pointed by 'head' does not
have a next element.  It is similar to the already existing
QMD_TAILQ_CHECK_TAIL(), but without the superfluous 'field' argument and
clearer documentation.  Use it in STAILQ_INSERT_TAIL().

Approved by:    markj (mentor)
MFC after:      2 weeks
Sponsored by:   The FreeBSD Foundation
Differential Revision:  https://reviews.freebsd.org/D46889

0 files changed, 0 insertions, 0 deletions