netdev - [PATCH net-next 07/14] ipv6: lockless IPV6_MULTICAST

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Date: Tue, 12 Sep 2023 16:02:05 +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: David Ahern <dsahern@...nel.org>, netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 07/14] ipv6: lockless IPV6_MULTICAST_ALL implementation

Move np->mc_all to an atomic flags to fix data-races.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/linux/ipv6.h     |  1 -
 include/net/inet_sock.h  |  1 +
 net/ipv6/af_inet6.c      |  2 +-
 net/ipv6/ipv6_sockglue.c | 14 ++++++--------
 net/ipv6/mcast.c         |  2 +-
 5 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 0d2b0a1b2daeaee51a03624adab5a385cc852cc7..d88e91b7f0a319a816488025ef213c4fb90ed359 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -255,7 +255,6 @@ struct ipv6_pinfo {
 				dontfrag:1,
 				autoflowlabel:1,
 				autoflowlabel_set:1,
-				mc_all:1,
 				rtalert_isolate:1;
 	__u8			min_hopcount;
 	__u8			tclass;
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 8cf1f7b442348bef83cc3d9648521a01667efae7..97e70a97dae888e6ab93c6446f4f3ba58cd8583e 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -270,6 +270,7 @@ enum {
 	INET_FLAGS_DEFER_CONNECT = 19,
 	INET_FLAGS_MC6_LOOP	= 20,
 	INET_FLAGS_RECVERR6_RFC4884 = 21,
+	INET_FLAGS_MC6_ALL	= 22,
 };
 
 /* cmsg flags for inet */
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index bbd4aa1b96d09d346c521dab2194045123e7a5a6..372fb7b9112c8dfed09b6ddfdb37016a1a668494 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -218,7 +218,7 @@ static int inet6_create(struct net *net, struct socket *sock, int protocol,
 	np->hop_limit	= -1;
 	np->mcast_hops	= IPV6_DEFAULT_MCASTHOPS;
 	inet6_set_bit(MC6_LOOP, sk);
-	np->mc_all	= 1;
+	inet6_set_bit(MC6_ALL, sk);
 	np->pmtudisc	= IPV6_PMTUDISC_WANT;
 	np->repflow	= net->ipv6.sysctl.flowlabel_reflect & FLOWLABEL_REFLECT_ESTABLISHED;
 	sk->sk_ipv6only	= net->ipv6.sysctl.bindv6only;
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index b65e73ac2ccdee79aa293948d3ba9853966e1e2d..7a181831f226c67813446145f8f58fa58908e3ae 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -469,6 +469,11 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 			return -EINVAL;
 		inet6_assign_bit(RECVERR6_RFC4884, sk, valbool);
 		return 0;
+	case IPV6_MULTICAST_ALL:
+		if (optlen < sizeof(int))
+			return -EINVAL;
+		inet6_assign_bit(MC6_ALL, sk, valbool);
+		return 0;
 	}
 	if (needs_rtnl)
 		rtnl_lock();
@@ -890,13 +895,6 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 			retv = ipv6_sock_ac_drop(sk, mreq.ipv6mr_ifindex, &mreq.ipv6mr_acaddr);
 		break;
 	}
-	case IPV6_MULTICAST_ALL:
-		if (optlen < sizeof(int))
-			goto e_inval;
-		np->mc_all = valbool;
-		retv = 0;
-		break;
-
 	case MCAST_JOIN_GROUP:
 	case MCAST_LEAVE_GROUP:
 		if (in_compat_syscall())
@@ -1372,7 +1370,7 @@ int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
 		break;
 
 	case IPV6_MULTICAST_ALL:
-		val = np->mc_all;
+		val = inet6_test_bit(MC6_ALL, sk);
 		break;
 
 	case IPV6_UNICAST_IF:
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 6a33a50687bcf7201e75574f03e619fe89636068..483f797ae44d538009184b5e53ad7755d73bab4a 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -642,7 +642,7 @@ bool inet6_mc_check(const struct sock *sk, const struct in6_addr *mc_addr,
 	}
 	if (!mc) {
 		rcu_read_unlock();
-		return np->mc_all;
+		return inet6_test_bit(MC6_ALL, sk);
 	}
 	psl = rcu_dereference(mc->sflist);
 	if (!psl) {
-- 
2.42.0.283.g2d96d420d3-goog