Keeping ifq_mfreem makes sense from a completeness point of view, but as
nothing makes use of it, why not move it to the Attic for a while?

Index: sys/net/ifq.c
===================================================================
RCS file: /OpenBSD/src/sys/net/ifq.c,v
diff -u -p -u -p -r1.62 ifq.c
--- sys/net/ifq.c	28 Jul 2025 05:25:44 -0000	1.62
+++ sys/net/ifq.c	20 Sep 2026 16:47:44 -0000
@@ -570,16 +570,6 @@ ifq_q_leave(struct ifqueue *ifq, void *q
 }
 
 void
-ifq_mfreem(struct ifqueue *ifq, struct mbuf *m)
-{
-	MUTEX_ASSERT_LOCKED(&ifq->ifq_mtx);
-
-	ifq->ifq_len--;
-	ifq->ifq_qdrops++;
-	ml_enqueue(&ifq->ifq_free, m);
-}
-
-void
 ifq_mfreeml(struct ifqueue *ifq, struct mbuf_list *ml)
 {
 	MUTEX_ASSERT_LOCKED(&ifq->ifq_mtx);
Index: sys/net/ifq.h
===================================================================
RCS file: /OpenBSD/src/sys/net/ifq.h,v
diff -u -p -u -p -r1.44 ifq.h
--- sys/net/ifq.h	4 Mar 2025 01:13:37 -0000	1.44
+++ sys/net/ifq.h	20 Sep 2026 16:47:44 -0000
@@ -213,15 +213,15 @@ struct ifiqueue {
  * The queue lock acquired with ifq_q_enter() is released with
  * ifq_q_leave().
  *
- * === ifq_mfreem() and ifq_mfreeml()
+ * === ifq_mfreeml()
  *
  * A goal of the API is to avoid freeing an mbuf while mutexes are
  * held. Because the ifq API manages the lock on behalf of the backend
  * ifqops, the backend should not directly free mbufs. If a conditioner
  * backend needs to drop a packet during the handling of ifqop_deq_begin,
- * it may free it by calling ifq_mfreem(). This accounts for the drop,
- * and schedules the free of the mbuf outside the hold of ifq_mtx.
- * ifq_mfreeml() takes an mbuf list as an argument instead.
+ * it may free it by calling ifq_mfreeml() with an mbuf list. This accounts
+ * for the drop, and schedules the free of the mbuf outside the hold of
+ * ifq_mtx.
  *
  *
  * == Network Driver API
@@ -437,7 +437,6 @@ void		 ifq_deq_rollback(struct ifqueue *
 struct mbuf	*ifq_dequeue(struct ifqueue *);
 int		 ifq_hdatalen(struct ifqueue *);
 void		 ifq_init_maxlen(struct ifqueue *, unsigned int);
-void		 ifq_mfreem(struct ifqueue *, struct mbuf *);
 void		 ifq_mfreeml(struct ifqueue *, struct mbuf_list *);
 unsigned int	 ifq_purge(struct ifqueue *);
 void		*ifq_q_enter(struct ifqueue *, const struct ifq_ops *);