net: remove DST_NOGC flag

Now that all the components have been changed to release dst based on
refcnt only and not depend on dst gc anymore, we can remove the
temporary flag DST_NOGC.

Note that we also need to remove the DST_NOCACHE check in dst_release()
and dst_hold_safe() because now all the dst are released based on refcnt
and behaves as DST_NOCACHE.
Signed-off-by: NWei Wang <weiwan@google.com>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/dst.h

@@ -57,7 +57,6 @@ struct dst_entry {
 #define DST_XFRM_TUNNEL		0x0080
 #define DST_XFRM_QUEUE		0x0100
 #define DST_METADATA		0x0200
-#define DST_NOGC		0x0400
 
 	short			error;
 
@@ -336,10 +335,7 @@ static inline void skb_dst_force(struct sk_buff *skb)
  */
 static inline bool dst_hold_safe(struct dst_entry *dst)
 {
-	if (dst->flags & (DST_NOCACHE | DST_NOGC))
-		return atomic_inc_not_zero(&dst->__refcnt);
-	dst_hold(dst);
-	return true;
+	return atomic_inc_not_zero(&dst->__refcnt);
 }
 
 /**

net/core/dst.c

@@ -179,14 +179,12 @@ void dst_release(struct dst_entry *dst)
 {
 	if (dst) {
 		int newrefcnt;
-		unsigned short destroy_after_rcu = dst->flags &
-						   (DST_NOCACHE | DST_NOGC);
 
 		newrefcnt = atomic_dec_return(&dst->__refcnt);
 		if (unlikely(newrefcnt < 0))
 			net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
 					     __func__, dst, newrefcnt);
-		if (!newrefcnt && unlikely(destroy_after_rcu))
+		if (!newrefcnt)
 			call_rcu(&dst->rcu_head, dst_destroy_rcu);
 	}
 }

net/decnet/dn_route.c

@@ -1179,8 +1179,7 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowidn *o
 	if (dev_out->flags & IFF_LOOPBACK)
 		flags |= RTCF_LOCAL;
 
-	rt = dst_alloc(&dn_dst_ops, dev_out, 1, DST_OBSOLETE_NONE,
-		       DST_HOST | DST_NOGC);
+	rt = dst_alloc(&dn_dst_ops, dev_out, 1, DST_OBSOLETE_NONE, DST_HOST);
 	if (rt == NULL)
 		goto e_nobufs;
 
@@ -1445,8 +1444,7 @@ static int dn_route_input_slow(struct sk_buff *skb)
 	}
 
 make_route:
-	rt = dst_alloc(&dn_dst_ops, out_dev, 1, DST_OBSOLETE_NONE,
-		       DST_HOST | DST_NOGC);
+	rt = dst_alloc(&dn_dst_ops, out_dev, 1, DST_OBSOLETE_NONE, DST_HOST);
 	if (rt == NULL)
 		goto e_nobufs;
 

net/ipv4/route.c

@@ -1496,8 +1496,7 @@ struct rtable *rt_dst_alloc(struct net_device *dev,
 	rt = dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
 		       (will_cache ? 0 : (DST_HOST | DST_NOCACHE)) |
 		       (nopolicy ? DST_NOPOLICY : 0) |
-		       (noxfrm ? DST_NOXFRM : 0) |
-		       DST_NOGC);
+		       (noxfrm ? DST_NOXFRM : 0));
 
 	if (rt) {
 		rt->rt_genid = rt_genid_ipv4(dev_net(dev));
@@ -2503,7 +2502,7 @@ struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_or
 	struct rtable *ort = (struct rtable *) dst_orig;
 	struct rtable *rt;
 
-	rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_NONE, DST_NOGC);
+	rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_NONE, 0);
 	if (rt) {
 		struct dst_entry *new = &rt->dst;
 

net/ipv6/route.c

@@ -354,8 +354,7 @@ static struct rt6_info *__ip6_dst_alloc(struct net *net,
 					int flags)
 {
 	struct rt6_info *rt = dst_alloc(&net->ipv6.ip6_dst_ops, dev,
-					1, DST_OBSOLETE_FORCE_CHK,
-					flags | DST_NOGC);
+					1, DST_OBSOLETE_FORCE_CHK, flags);
 
 	if (rt)
 		rt6_info_init(rt);
@@ -1255,7 +1254,7 @@ struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_ori
 	struct dst_entry *new = NULL;
 
 	rt = dst_alloc(&ip6_dst_blackhole_ops, loopback_dev, 1,
-		       DST_OBSOLETE_NONE, DST_NOGC);
+		       DST_OBSOLETE_NONE, 0);
 	if (rt) {
 		rt6_info_init(rt);
 

net/xfrm/xfrm_policy.c

@@ -1622,7 +1622,7 @@ static inline struct xfrm_dst *xfrm_alloc_dst(struct net *net, int family)
 	default:
 		BUG();
 	}
-	xdst = dst_alloc(dst_ops, NULL, 1, DST_OBSOLETE_NONE, DST_NOGC);
+	xdst = dst_alloc(dst_ops, NULL, 1, DST_OBSOLETE_NONE, 0);
 
 	if (likely(xdst)) {
 		struct dst_entry *dst = &xdst->u.dst;