queue(3) NOTES says The SLIST_END(), LIST_END(), SIMPLEQ_END(), STAILQ_END() and TAILQ_END() macros are deprecated; they provided symmetry with the historical CIRCLEQ_END() and just expand to NULL.
We still have one user, though: $ cd /usr/src/ $ grep -rslwE '(S?LIST|(SIMPLE|S?TAIL))Q_END' sys/dev/pci/pci.c sys/sys/smr.h sys/sys/queue.h share/man/man3/queue.3 No object change. OK? Index: pci.c =================================================================== RCS file: /cvs/src/sys/dev/pci/pci.c,v retrieving revision 1.125 diff -u -p -r1.125 pci.c --- pci.c 17 Jun 2022 10:08:36 -0000 1.125 +++ pci.c 27 Nov 2022 22:04:51 -0000 @@ -1293,7 +1293,7 @@ pciioctl(dev_t dev, u_long cmd, caddr_t func == sel->pc_func) break; } - if (pd == LIST_END(&pci->sc_devs)) + if (pd == NULL) return ENXIO; tag = pci_make_tag(pc, sel->pc_bus, sel->pc_dev, sel->pc_func);