[net,2/2] net: mpls: Remove rcu protection from nh_dev

Commit Message

Benjamin Poirier Nov. 29, 2021, 6:15 a.m. UTC

Following the previous commit, nh_dev can no longer be accessed and
modified concurrently.

Signed-off-by: Benjamin Poirier <[e-mail]>
---
 net/mpls/af_mpls.c  | 39 +++++++++++++++------------------------
 net/mpls/internal.h |  2 +-
 2 files changed, 16 insertions(+), 25 deletions(-)

Patch

diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 6e587feb705c..0c7bde1c14a6 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -409,7 +409,7 @@  static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
 		goto err;
 
 	/* Find the output device */
-	out_dev = rcu_dereference(nh->nh_dev);
+	out_dev = nh->nh_dev;
 	if (!mpls_output_possible(out_dev))
 		goto tx_err;
 
@@ -698,7 +698,7 @@  static int mpls_nh_assign_dev(struct net *net, struct mpls_route *rt,
 	    (dev->addr_len != nh->nh_via_alen))
 		goto errout;
 
-	RCU_INIT_POINTER(nh->nh_dev, dev);
+	nh->nh_dev = dev;
 
 	if (!(dev->flags & IFF_UP)) {
 		nh->nh_flags |= RTNH_F_DEAD;
@@ -1510,12 +1510,9 @@  static int mpls_ifdown(struct net_device *dev, int event)
 			u8 deleted = 0;
 
 			for_nexthops(rt) {
-				struct net_device *nh_dev =
-					rtnl_dereference(nh->nh_dev);
-
-				if (!nh_dev || nh_dev == dev)
+				if (!nh->nh_dev || nh->nh_dev == dev)
 					deleted++;
-				if (nh_dev == dev)
+				if (nh->nh_dev == dev)
 					nh_del = true;
 			} endfor_nexthops(rt);
 
@@ -1540,7 +1537,7 @@  static int mpls_ifdown(struct net_device *dev, int event)
 		change_nexthops(rt) {
 			unsigned int nh_flags = nh->nh_flags;
 
-			if (rtnl_dereference(nh->nh_dev) != dev)
+			if (nh->nh_dev != dev)
 				goto next;
 
 			switch (event) {
@@ -1553,7 +1550,7 @@  static int mpls_ifdown(struct net_device *dev, int event)
 				break;
 			}
 			if (event == NETDEV_UNREGISTER)
-				RCU_INIT_POINTER(nh->nh_dev, NULL);
+				nh->nh_dev = NULL;
 
 			if (nh->nh_flags != nh_flags)
 				WRITE_ONCE(nh->nh_flags, nh_flags);
@@ -1588,14 +1585,12 @@  static void mpls_ifup(struct net_device *dev, unsigned int flags)
 		alive = 0;
 		change_nexthops(rt) {
 			unsigned int nh_flags = nh->nh_flags;
-			struct net_device *nh_dev =
-				rtnl_dereference(nh->nh_dev);
 
 			if (!(nh_flags & flags)) {
 				alive++;
 				continue;
 			}
-			if (nh_dev != dev)
+			if (nh->nh_dev != dev)
 				continue;
 			alive++;
 			nh_flags &= ~flags;
@@ -2030,7 +2025,7 @@  static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
 		    nla_put_via(skb, nh->nh_via_table, mpls_nh_via(rt, nh),
 				nh->nh_via_alen))
 			goto nla_put_failure;
-		dev = rtnl_dereference(nh->nh_dev);
+		dev = nh->nh_dev;
 		if (dev && nla_put_u32(skb, RTA_OIF, dev->ifindex))
 			goto nla_put_failure;
 		if (nh->nh_flags & RTNH_F_LINKDOWN)
@@ -2048,7 +2043,7 @@  static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
 			goto nla_put_failure;
 
 		for_nexthops(rt) {
-			dev = rtnl_dereference(nh->nh_dev);
+			dev = nh->nh_dev;
 			if (!dev)
 				continue;
 
@@ -2159,18 +2154,14 @@  static int mpls_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh,
 static bool mpls_rt_uses_dev(struct mpls_route *rt,
 			     const struct net_device *dev)
 {
-	struct net_device *nh_dev;
-
 	if (rt->rt_nhn == 1) {
 		struct mpls_nh *nh = rt->rt_nh;
 
-		nh_dev = rtnl_dereference(nh->nh_dev);
-		if (dev == nh_dev)
+		if (nh->nh_dev == dev)
 			return true;
 	} else {
 		for_nexthops(rt) {
-			nh_dev = rtnl_dereference(nh->nh_dev);
-			if (nh_dev == dev)
+			if (nh->nh_dev == dev)
 				return true;
 		} endfor_nexthops(rt);
 	}
@@ -2258,7 +2249,7 @@  static inline size_t lfib_nlmsg_size(struct mpls_route *rt)
 		size_t nhsize = 0;
 
 		for_nexthops(rt) {
-			if (!rtnl_dereference(nh->nh_dev))
+			if (!nh->nh_dev)
 				continue;
 			nhsize += nla_total_size(sizeof(struct rtnexthop));
 			/* RTA_VIA */
@@ -2504,7 +2495,7 @@  static int mpls_getroute(struct sk_buff *in_skb, struct nlmsghdr *in_nlh,
 	    nla_put_via(skb, nh->nh_via_table, mpls_nh_via(rt, nh),
 			nh->nh_via_alen))
 		goto nla_put_failure;
-	dev = rtnl_dereference(nh->nh_dev);
+	dev = nh->nh_dev;
 	if (dev && nla_put_u32(skb, RTA_OIF, dev->ifindex))
 		goto nla_put_failure;
 
@@ -2543,7 +2534,7 @@  static int resize_platform_label_table(struct net *net, size_t limit)
 		rt0 = mpls_rt_alloc(1, lo->addr_len, 0);
 		if (IS_ERR(rt0))
 			goto nort0;
-		RCU_INIT_POINTER(rt0->rt_nh->nh_dev, lo);
+		rt0->rt_nh->nh_dev = lo;
 		rt0->rt_protocol = RTPROT_KERNEL;
 		rt0->rt_payload_type = MPT_IPV4;
 		rt0->rt_ttl_propagate = MPLS_TTL_PROP_DEFAULT;
@@ -2557,7 +2548,7 @@  static int resize_platform_label_table(struct net *net, size_t limit)
 		rt2 = mpls_rt_alloc(1, lo->addr_len, 0);
 		if (IS_ERR(rt2))
 			goto nort2;
-		RCU_INIT_POINTER(rt2->rt_nh->nh_dev, lo);
+		rt2->rt_nh->nh_dev = lo;
 		rt2->rt_protocol = RTPROT_KERNEL;
 		rt2->rt_payload_type = MPT_IPV6;
 		rt2->rt_ttl_propagate = MPLS_TTL_PROP_DEFAULT;
diff --git a/net/mpls/internal.h b/net/mpls/internal.h
index 838cdfc10e47..893df00b77b6 100644
--- a/net/mpls/internal.h
+++ b/net/mpls/internal.h
@@ -87,7 +87,7 @@  enum mpls_payload_type {
 };
 
 struct mpls_nh { /* next hop label forwarding entry */
-	struct net_device __rcu *nh_dev;
+	struct net_device	*nh_dev;
 
 	/* nh_flags is accessed under RCU in the packet path; it is
 	 * modified handling netdev events with rtnl lock held