Index: head/share/man/man9/refcount.9
===================================================================
--- head/share/man/man9/refcount.9
+++ head/share/man/man9/refcount.9
@@ -32,7 +32,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 23, 2019
+.Dd November 2, 2020
 .Dt REFCOUNT 9
 .Os
 .Sh NAME
@@ -46,6 +46,8 @@
 .In sys/refcount.h
 .Ft void
 .Fn refcount_init "volatile u_int *count" "u_int value"
+.Ft u_int
+.Fn refcount_load "volatile u_int *count"
 .Ft void
 .Fn refcount_acquire "volatile u_int *count"
 .Ft bool
@@ -55,6 +57,8 @@
 .Ft bool
 .Fn refcount_release "volatile u_int *count"
 .Ft bool
+.Fn refcount_release_if_last "volatile u_int *count"
+.Ft bool
 .Fn refcount_release_if_not_last "volatile u_int *count"
 .Sh DESCRIPTION
 The
@@ -75,6 +79,16 @@
 It is normally used when creating a reference-counted object.
 .Pp
 The
+.Fn refcount_load
+function returns a snapshot of the counter value.
+This value may immediately become out-of-date in the absence of external
+synchronization.
+.Fn refcount_load
+should be used instead of relying on the properties of the
+.Vt volatile
+qualifier.
+.Pp
+The
 .Fn refcount_acquire
 function is used to acquire a new reference.
 The caller is responsible for ensuring that it holds a valid reference
@@ -119,16 +133,33 @@
 otherwise, it returns false.
 .Pp
 The
+.Fn refcount_release_if_last
+and
 .Fn refcount_release_if_not_last
-is a variant of
+functions are variants of
 .Fn refcount_release
-which only drops the reference when it is not the last reference.
-In other words, the function returns
+which only drop the reference when it is or is not the last reference,
+respectively.
+In other words,
+.Fn refcount_release_if_last
+returns
 .Dv true
 when
 .Fa *count
+is equal to one, in which case it is decremented to zero.
+Otherwise,
+.Fa *count
+is not modified and the function returns
+.Dv false .
+Similarly,
+.Fn refcount_release_if_not_last
+returns
+.Dv true
+when
+.Fa *count
 is greater than one, in which case
-.Fa *count is decremented.
+.Fa *count
+is decremented.
 Otherwise, if
 .Fa *count
 is equal to one, the reference is not released and the function returns
Index: head/sys/sys/refcount.h
===================================================================
--- head/sys/sys/refcount.h
+++ head/sys/sys/refcount.h
@@ -67,6 +67,12 @@
 }
 
 static __inline u_int
+refcount_load(volatile u_int *count)
+{
+	return (atomic_load_int(count));
+}
+
+static __inline u_int
 refcount_acquire(volatile u_int *count)
 {
 	u_int old;
@@ -168,32 +174,50 @@
 	return (refcount_releasen(count, 1));
 }
 
+#define	_refcount_release_if_cond(cond, name)				\
+static __inline __result_use_check bool					\
+_refcount_release_if_##name(volatile u_int *count, u_int n)		\
+{									\
+	u_int old;							\
+									\
+	KASSERT(n > 0, ("%s: zero increment", __func__));		\
+	old = atomic_load_int(count);					\
+	for (;;) {							\
+		if (!(cond))						\
+			return (false);					\
+		if (__predict_false(REFCOUNT_SATURATED(old)))		\
+			return (false);					\
+		if (atomic_fcmpset_rel_int(count, &old, old - 1))	\
+			return (true);					\
+	}								\
+}
+_refcount_release_if_cond(old > n, gt)
+_refcount_release_if_cond(old == n, eq)
+
 static __inline __result_use_check bool
 refcount_release_if_gt(volatile u_int *count, u_int n)
 {
-	u_int old;
 
-	KASSERT(n > 0,
-	    ("refcount_release_if_gt: Use refcount_release for final ref"));
-	old = atomic_load_int(count);
-	for (;;) {
-		if (old <= n)
-			return (false);
-		if (__predict_false(REFCOUNT_SATURATED(old)))
-			return (true);
-		/*
-		 * Paired with acquire fence in refcount_releasen().
-		 */
-		if (atomic_fcmpset_rel_int(count, &old, old - 1))
-			return (true);
+	return (_refcount_release_if_gt(count, n));
+}
+
+static __inline __result_use_check bool
+refcount_release_if_last(volatile u_int *count)
+{
+
+	if (_refcount_release_if_eq(count, 1)) {
+		/* See the comment in refcount_releasen(). */
+		atomic_thread_fence_acq();
+		return (true);
 	}
+	return (false);
 }
 
 static __inline __result_use_check bool
 refcount_release_if_not_last(volatile u_int *count)
 {
 
-	return (refcount_release_if_gt(count, 1));
+	return (_refcount_release_if_gt(count, 1));
 }
 
 #endif /* !__SYS_REFCOUNT_H__ */