From: Eric Dumazet <edumazet@google.com>
Date: Wed, 9 Oct 2024 18:44:04 +0000 (+0000)
Subject: ipmr: use READ_ONCE() to read net->ipv[46].ipmr_seq
X-Git-Tag: v6.13-rc1~135^2~349^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=055202b16c589cc82cc8ab9d4316701547fb8853;p=thirdparty%2Fkernel%2Flinux.git

ipmr: use READ_ONCE() to read net->ipv[46].ipmr_seq

mr_call_vif_notifiers() and mr_call_mfc_notifiers() already
uses WRITE_ONCE() on the write side.

Using RTNL to protect the reads seems a big hammer.

Constify 'struct net' argument of ip6mr_rules_seq_read()
and ipmr_rules_seq_read().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20241009184405.3752829-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 089864c6a35ee..35ed031651842 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -288,7 +288,7 @@ static int ipmr_rules_dump(struct net *net, struct notifier_block *nb,
 	return fib_rules_dump(net, nb, RTNL_FAMILY_IPMR, extack);
 }
 
-static unsigned int ipmr_rules_seq_read(struct net *net)
+static unsigned int ipmr_rules_seq_read(const struct net *net)
 {
 	return fib_rules_seq_read(net, RTNL_FAMILY_IPMR);
 }
@@ -346,7 +346,7 @@ static int ipmr_rules_dump(struct net *net, struct notifier_block *nb,
 	return 0;
 }
 
-static unsigned int ipmr_rules_seq_read(struct net *net)
+static unsigned int ipmr_rules_seq_read(const struct net *net)
 {
 	return 0;
 }
@@ -3037,9 +3037,7 @@ static const struct net_protocol pim_protocol = {
 
 static unsigned int ipmr_seq_read(struct net *net)
 {
-	ASSERT_RTNL();
-
-	return net->ipv4.ipmr_seq + ipmr_rules_seq_read(net);
+	return READ_ONCE(net->ipv4.ipmr_seq) + ipmr_rules_seq_read(net);
 }
 
 static int ipmr_dump(struct net *net, struct notifier_block *nb,
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 2ce4ae0d8dc3b..3f9501fd8c1ae 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -276,7 +276,7 @@ static int ip6mr_rules_dump(struct net *net, struct notifier_block *nb,
 	return fib_rules_dump(net, nb, RTNL_FAMILY_IP6MR, extack);
 }
 
-static unsigned int ip6mr_rules_seq_read(struct net *net)
+static unsigned int ip6mr_rules_seq_read(const struct net *net)
 {
 	return fib_rules_seq_read(net, RTNL_FAMILY_IP6MR);
 }
@@ -335,7 +335,7 @@ static int ip6mr_rules_dump(struct net *net, struct notifier_block *nb,
 	return 0;
 }
 
-static unsigned int ip6mr_rules_seq_read(struct net *net)
+static unsigned int ip6mr_rules_seq_read(const struct net *net)
 {
 	return 0;
 }
@@ -1262,9 +1262,7 @@ static int ip6mr_device_event(struct notifier_block *this,
 
 static unsigned int ip6mr_seq_read(struct net *net)
 {
-	ASSERT_RTNL();
-
-	return net->ipv6.ipmr_seq + ip6mr_rules_seq_read(net);
+	return READ_ONCE(net->ipv6.ipmr_seq) + ip6mr_rules_seq_read(net);
 }
 
 static int ip6mr_dump(struct net *net, struct notifier_block *nb,