From nobody Mon Apr 6 09:12:03 2026 Received: from mail.aperture-lab.de (mail.aperture-lab.de [116.203.183.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7E6D2355F5C; Sat, 7 Mar 2026 04:46:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=116.203.183.178 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772858780; cv=none; b=Yxgc+p2RLUEg9NNGZ+p2Vt3q+2y9iJS1YjmWsZimqEomU5XYsjH9Bc09Vf24G0NqBX5BEDES7UwZLm0/73vcz5gzMv3YodRCt2FnXzR7aoigrfY8xHJsg1OJAx2bVA3DutZbgo39uCtkKXrfb0w1IIbEQ6xFdIxf7wqGATTtOSA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772858780; c=relaxed/simple; bh=qEndSg74IrSsHyC+dBq6x34fpvQkg8HB8RGj8cYl2Wg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=gsDo6U6dVMXHZefNfQ1/GWc92br6JTVdhUz4Rm1p/+sg9Nn36NpycAgzwh72QKimOPbiYwaiGCp8XiPnseRCYl2eLZiKIVUSDAHxxyNDud8ts98MG5beWhzAhaHq/NuLfCM6aVCeu7TLJtONqjPakxwmdoj1XAIJTBK2AgaqsQo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=c0d3.blue; spf=pass smtp.mailfrom=c0d3.blue; arc=none smtp.client-ip=116.203.183.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=c0d3.blue Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=c0d3.blue Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 174B554C936; Sat, 7 Mar 2026 05:46:16 +0100 (CET) From: =?UTF-8?q?Linus=20L=C3=BCssing?= To: bridge@lists.linux.dev Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Nikolay Aleksandrov , Ido Schimmel , Andrew Lunn , Simon Horman , Paolo Abeni , Jakub Kicinski , Eric Dumazet , "David S . Miller" , Kuniyuki Iwashima , Stanislav Fomichev , Xiao Liang , shuah@kernel.org, petrm@nvidia.com, =?UTF-8?q?Linus=20L=C3=BCssing?= Subject: [PATCH net-next v4 11/14] net: bridge: mcast: track active state, prepare for outside lock reads Date: Sat, 7 Mar 2026 05:45:45 +0100 Message-ID: <20260307044548.5230-12-linus.luessing@c0d3.blue> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260307044548.5230-1-linus.luessing@c0d3.blue> References: <20260307044548.5230-1-linus.luessing@c0d3.blue> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Last-TLS-Session-Version: TLSv1.3 We are updating ip{4,6}_active and check all variables their state relies on while holding the bridge multicast spinlock. However we are going to read it without this lock in a follow-up commit on fast/data path, too. As these variables are only booleans this shouldn't be a problem, ip{4,6}_active will be loaded and stored atomically. And those read sides should converge eventually. But to allow tooling to verify this use the READ_ONCE() and WRITE_ONCE macros. Signed-off-by: Linus L=C3=BCssing --- net/bridge/br_multicast.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index cb78f9555db6..6faa484dede7 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -1085,9 +1085,10 @@ static void br_ip4_multicast_update_active(struct ne= t_bridge_mcast *brmctx, bool force_inactive) { if (force_inactive) - brmctx->ip4_active =3D false; + WRITE_ONCE(brmctx->ip4_active, false); else - brmctx->ip4_active =3D br_ip4_multicast_querier_exists(brmctx); + WRITE_ONCE(brmctx->ip4_active, + br_ip4_multicast_querier_exists(brmctx)); } =20 static void br_ip6_multicast_update_active(struct net_bridge_mcast *brmctx, @@ -1095,23 +1096,26 @@ static void br_ip6_multicast_update_active(struct n= et_bridge_mcast *brmctx, { #if IS_ENABLED(CONFIG_IPV6) if (force_inactive) - brmctx->ip6_active =3D false; + WRITE_ONCE(brmctx->ip6_active, false); else - brmctx->ip6_active =3D br_ip6_multicast_querier_exists(brmctx); + WRITE_ONCE(brmctx->ip6_active, + br_ip6_multicast_querier_exists(brmctx)); #endif } =20 static void br_multicast_notify_active(struct net_bridge_mcast *brmctx, bool ip4_active_old, bool ip6_active_old) { - if (brmctx->ip4_active =3D=3D ip4_active_old && - brmctx->ip6_active =3D=3D ip6_active_old) + int ip4_active =3D brmctx->ip4_active; + int ip6_active =3D brmctx->ip6_active; + + if (ip4_active =3D=3D ip4_active_old && + ip6_active =3D=3D ip6_active_old) return; =20 br_debug(brmctx->br, "mc_active changed, vid: %i: v4: %i->%i, v6: %i->%i\= n", brmctx->vlan ? brmctx->vlan->vid : -1, - ip4_active_old, brmctx->ip4_active, - ip6_active_old, brmctx->ip6_active); + ip4_active_old, ip4_active, ip6_active_old, ip6_active); } =20 /** @@ -4269,7 +4273,7 @@ void br_multicast_ctx_init(struct net_bridge *br, brmctx->multicast_membership_interval =3D 260 * HZ; =20 brmctx->ip4_querier.port_ifidx =3D 0; - brmctx->ip4_active =3D 0; + WRITE_ONCE(brmctx->ip4_active, 0); seqcount_spinlock_init(&brmctx->ip4_querier.seq, &br->multicast_lock); brmctx->multicast_igmp_version =3D 2; #if IS_ENABLED(CONFIG_IPV6) @@ -4277,7 +4281,7 @@ void br_multicast_ctx_init(struct net_bridge *br, brmctx->ip6_querier.port_ifidx =3D 0; seqcount_spinlock_init(&brmctx->ip6_querier.seq, &br->multicast_lock); #endif - brmctx->ip6_active =3D 0; + WRITE_ONCE(brmctx->ip6_active, 0); =20 timer_setup(&brmctx->ip4_mc_router_timer, NULL, 0); timer_setup(&brmctx->ip4_other_query.timer, NULL, 0); --=20 2.53.0