Index: sys/srp.h
===================================================================
RCS file: /cvs/src/sys/sys/srp.h,v
retrieving revision 1.7
diff -u -p -r1.7 srp.h
--- sys/srp.h	3 Dec 2015 16:27:32 -0000	1.7
+++ sys/srp.h	7 Apr 2016 03:56:56 -0000
@@ -56,11 +56,13 @@ void		 srp_update(struct srp_gc *, struc
 void		*srp_enter(struct srp *);
 void		*srp_follow(struct srp *, void *, struct srp *);
 void		 srp_leave(struct srp *, void *);
+void		 srp_wait(void *);
 #else /* MULTIPROCESSOR */
 #define srp_update(_gc, _srp, _v)	srp_update_locked((_gc), (_srp), (_v))
 #define srp_enter(_srp)			((_srp)->ref)
 #define srp_follow(_srp, _v, _next)	((_next)->ref)
 #define srp_leave(_srp, _v)		do { } while (0)
+#define srp_wait(_srp, _v)		do { } while (0)
 #endif /* MULTIPROCESSOR */
 
 #endif /* _KERNEL */
Index: kern/kern_srp.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_srp.c,v
retrieving revision 1.7
diff -u -p -r1.7 kern_srp.c
--- kern/kern_srp.c	23 Nov 2015 10:56:19 -0000	1.7
+++ kern/kern_srp.c	7 Apr 2016 03:56:56 -0000
@@ -260,6 +260,33 @@ srp_leave(struct srp *srp, void *v)
 	panic("%s: unexpected ref %p via %p", __func__, v, srp);
 }
 
+static inline int
+srp_referenced(void *v)
+{
+	struct cpu_info *ci;
+	CPU_INFO_ITERATOR cii;
+	u_int i;
+	struct srp_hazard *hzrd;
+
+	CPU_INFO_FOREACH(cii, ci) {
+		for (i = 0; i < nitems(ci->ci_srp_hazards); i++) {
+			hzrd = &ci->ci_srp_hazards[i];
+
+			if (hzrd->sh_v == v)
+				return (1);
+		}
+	}
+
+	return (0);
+}
+
+void
+srp_wait(void *v)
+{
+	while (srp_referenced(v))
+		tsleep(v, PWAIT, "srpwait", 1);
+}
+
 #else /* MULTIPROCESSOR */
 
 void