From 26dd4278000890378d1660509fc68c2a03aa4fcb Mon Sep 17 00:00:00 2001
From: Mark Johnston <markj@FreeBSD.org>
Date: Mon, 6 Jul 2020 21:20:57 +0000
Subject: [PATCH] Split nhop_ref_object().

Now nhop_ref_object() unconditionally acquires a reference, and the new
nhop_try_ref_object() uses refcount_acquire_if_not_zero() to
conditionally acquire a reference.  Since the former is cheaper, use it
when we know that the initial counter value is non-zero.  No functional
change intended.

Reviewed by:	melifaro
Differential Revision:	https://reviews.freebsd.org/D25535
---
 sys/net/route/nhop_ctl.c | 13 +++++++++++--
 sys/net/route/shared.h   |  3 ++-
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/sys/net/route/nhop_ctl.c b/sys/net/route/nhop_ctl.c
index 2d74faa212ce..7787d403eb84 100644
--- a/sys/net/route/nhop_ctl.c
+++ b/sys/net/route/nhop_ctl.c
@@ -598,8 +598,17 @@ destroy_nhop_epoch(epoch_context_t ctx)
 	destroy_nhop(nh_priv);
 }
 
-int
+void
 nhop_ref_object(struct nhop_object *nh)
+{
+	u_int old;
+
+	old = refcount_acquire(&nh->nh_priv->nh_refcnt);
+	KASSERT(old > 0, ("%s: nhop object %p has 0 refs", __func__, nh));
+}
+
+int
+nhop_try_ref_object(struct nhop_object *nh)
 {
 
 	return (refcount_acquire_if_not_zero(&nh->nh_priv->nh_refcnt));
@@ -654,7 +663,7 @@ int
 nhop_ref_any(struct nhop_object *nh)
 {
 
-	return (nhop_ref_object(nh));
+	return (nhop_try_ref_object(nh));
 }
 
 void
diff --git a/sys/net/route/shared.h b/sys/net/route/shared.h
index bca0467d891d..ce5075896c96 100644
--- a/sys/net/route/shared.h
+++ b/sys/net/route/shared.h
@@ -51,7 +51,8 @@ struct rib_head;
 void nhops_init(void);
 int nhops_init_rib(struct rib_head *rh);
 void nhops_destroy_rib(struct rib_head *rh);
-int nhop_ref_object(struct nhop_object *nh);
+void nhop_ref_object(struct nhop_object *nh);
+int nhop_try_ref_object(struct nhop_object *nh);
 int nhop_ref_any(struct nhop_object *nh);
 void nhop_free_any(struct nhop_object *nh);