From mboxrd@z Thu Jan 1 00:00:00 1970 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 C151A324718; Mon, 2 Mar 2026 05:40:57 +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=1772430059; cv=none; b=ARls/8WrQJzZ2XEz6N399KhWMOmifIngdUTxd2FBl/0I0JHH70WU54QhMEPR0AQVD3pkPvYm9fBIYS5L+Ph9e23P9kBJvyTuH1m27yTwUB6Xq9452iA6bAcALuaK2prxqnmdD8RPYAxQ+AMrgkLxkBSHOgbNv8pMV8MSthO6/cM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772430059; c=relaxed/simple; bh=jvBSBWd5IWs/b49CVRn+6ZYlDfgfqyySBV3Fm4/20+U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=jMftndo9Ff23VFqeO0cMpdaIMXCfF5AXbQUbMmOg9jqfyBjshtDypwKCTM0mBaZBh9X7fMGwbMThiWpgrSf3LbEn3w//nisGML8kcmThEmemHA6lEmfu/jtAMZcrGdzfqgVriuM+cBkrn9VnGPvg19Fa5OMpcCGJRoSzeTWXg7s= 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 8128C54CC77; Mon, 2 Mar 2026 06:40:55 +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, =?UTF-8?q?Linus=20L=C3=BCssing?= Subject: [PATCH net-next v3 11/14] net: bridge: mcast: track active state, prepare for outside lock reads Date: Mon, 2 Mar 2026 06:40:05 +0100 Message-ID: <20260302054008.21638-12-linus.luessing@c0d3.blue> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260302054008.21638-1-linus.luessing@c0d3.blue> References: <20260302054008.21638-1-linus.luessing@c0d3.blue> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Lüssing --- net/bridge/br_multicast.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index 8eedb98378b6..715a0e0aa5ad 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -1083,9 +1083,9 @@ static void br_ip4_multicast_update_active(struct net_bridge_mcast *brmctx, bool force_inactive) { if (force_inactive) - brmctx->ip4_active = false; + WRITE_ONCE(brmctx->ip4_active, false); else - brmctx->ip4_active = br_ip4_multicast_querier_exists(brmctx); + WRITE_ONCE(brmctx->ip4_active, br_ip4_multicast_querier_exists(brmctx)); } static void br_ip6_multicast_update_active(struct net_bridge_mcast *brmctx, @@ -1093,23 +1093,25 @@ static void br_ip6_multicast_update_active(struct net_bridge_mcast *brmctx, { #if IS_ENABLED(CONFIG_IPV6) if (force_inactive) - brmctx->ip6_active = false; + WRITE_ONCE(brmctx->ip6_active, false); else - brmctx->ip6_active = br_ip6_multicast_querier_exists(brmctx); + WRITE_ONCE(brmctx->ip6_active, br_ip6_multicast_querier_exists(brmctx)); #endif } static void br_multicast_notify_active(struct net_bridge_mcast *brmctx, bool ip4_active_old, bool ip6_active_old) { - if (brmctx->ip4_active == ip4_active_old && - brmctx->ip6_active == ip6_active_old) + int ip4_active = brmctx->ip4_active; + int ip6_active = brmctx->ip6_active; + + if (ip4_active == ip4_active_old && + ip6_active == ip6_active_old) return; 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); } /** @@ -1134,7 +1136,8 @@ static void br_multicast_notify_active(struct net_bridge_mcast *brmctx, */ static void br_multicast_update_active(struct net_bridge_mcast *brmctx) { - bool ip4_active_old = brmctx->ip4_active, ip6_active_old = brmctx->ip6_active; + bool ip4_active_old = brmctx->ip4_active; + bool ip6_active_old = brmctx->ip6_active; bool force_inactive = false; lockdep_assert_held_once(&brmctx->br->multicast_lock); @@ -4261,13 +4264,13 @@ void br_multicast_ctx_init(struct net_bridge *br, brmctx->multicast_membership_interval = 260 * HZ; brmctx->ip4_querier.port_ifidx = 0; - brmctx->ip4_active = 0; + WRITE_ONCE(brmctx->ip4_active, 0); seqcount_spinlock_init(&brmctx->ip4_querier.seq, &br->multicast_lock); brmctx->multicast_igmp_version = 2; #if IS_ENABLED(CONFIG_IPV6) brmctx->multicast_mld_version = 1; brmctx->ip6_querier.port_ifidx = 0; - brmctx->ip6_active = 0; + WRITE_ONCE(brmctx->ip6_active, 0); seqcount_spinlock_init(&brmctx->ip6_querier.seq, &br->multicast_lock); #endif -- 2.51.0