netdev - [PATCH v4 net-next 02/13] ip_tunnel: annotate data-races around t->parms.link

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Date: Tue, 13 Feb 2024 06:32:34 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH v4 net-next 02/13] ip_tunnel: annotate data-races around t->parms.link

t->parms.link is read locklessly, annotate these reads
and opposite writes accordingly.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/ip_tunnel.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 00da0b80320fb514bca58de7cd13894ab49a2ca6..248eb2d9829b31f89b7700460e317bf88bf325d9 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -102,10 +102,9 @@ struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net *itn,
 		if (!ip_tunnel_key_match(&t->parms, flags, key))
 			continue;
 
-		if (t->parms.link == link)
+		if (READ_ONCE(t->parms.link) == link)
 			return t;
-		else
-			cand = t;
+		cand = t;
 	}
 
 	hlist_for_each_entry_rcu(t, head, hash_node) {
@@ -117,9 +116,9 @@ struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net *itn,
 		if (!ip_tunnel_key_match(&t->parms, flags, key))
 			continue;
 
-		if (t->parms.link == link)
+		if (READ_ONCE(t->parms.link) == link)
 			return t;
-		else if (!cand)
+		if (!cand)
 			cand = t;
 	}
 
@@ -137,9 +136,9 @@ struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net *itn,
 		if (!ip_tunnel_key_match(&t->parms, flags, key))
 			continue;
 
-		if (t->parms.link == link)
+		if (READ_ONCE(t->parms.link) == link)
 			return t;
-		else if (!cand)
+		if (!cand)
 			cand = t;
 	}
 
@@ -150,9 +149,9 @@ struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net *itn,
 		    !(t->dev->flags & IFF_UP))
 			continue;
 
-		if (t->parms.link == link)
+		if (READ_ONCE(t->parms.link) == link)
 			return t;
-		else if (!cand)
+		if (!cand)
 			cand = t;
 	}
 
@@ -221,7 +220,7 @@ static struct ip_tunnel *ip_tunnel_find(struct ip_tunnel_net *itn,
 	hlist_for_each_entry_rcu(t, head, hash_node) {
 		if (local == t->parms.iph.saddr &&
 		    remote == t->parms.iph.daddr &&
-		    link == t->parms.link &&
+		    link == READ_ONCE(t->parms.link) &&
 		    type == t->dev->type &&
 		    ip_tunnel_key_match(&t->parms, flags, key))
 			break;
@@ -747,7 +746,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 
 	ip_tunnel_init_flow(&fl4, protocol, dst, tnl_params->saddr,
 			    tunnel->parms.o_key, RT_TOS(tos),
-			    dev_net(dev), tunnel->parms.link,
+			    dev_net(dev), READ_ONCE(tunnel->parms.link),
 			    tunnel->fwmark, skb_get_hash(skb), 0);
 
 	if (ip_tunnel_encap(skb, &tunnel->encap, &protocol, &fl4) < 0)
@@ -867,7 +866,7 @@ static void ip_tunnel_update(struct ip_tunnel_net *itn,
 	if (t->parms.link != p->link || t->fwmark != fwmark) {
 		int mtu;
 
-		t->parms.link = p->link;
+		WRITE_ONCE(t->parms.link, p->link);
 		t->fwmark = fwmark;
 		mtu = ip_tunnel_bind_dev(dev);
 		if (set_mtu)
@@ -1057,9 +1056,9 @@ EXPORT_SYMBOL(ip_tunnel_get_link_net);
 
 int ip_tunnel_get_iflink(const struct net_device *dev)
 {
-	struct ip_tunnel *tunnel = netdev_priv(dev);
+	const struct ip_tunnel *tunnel = netdev_priv(dev);
 
-	return tunnel->parms.link;
+	return READ_ONCE(tunnel->parms.link);
 }
 EXPORT_SYMBOL(ip_tunnel_get_iflink);
 
-- 
2.43.0.687.g38aa6559b0-goog