From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9F06530B50F; Mon, 13 Oct 2025 15:32:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760369543; cv=none; b=u7SHJud3Q5r8IoOTtY1YT/ZSygtYSVUvnblNEE0AmXKZylhbcoPzWgbNQ+WWPE+vp33ki3b82XBzFJpDbFl8Uq9VvCs04Tsb28D0RUUKRcaU0DCCDdkxZAU7msevveR283plJcuD6bExfApAavg8j8121ylMY6S506uwLYZFmYs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760369543; c=relaxed/simple; bh=LS7Sv0eWZDH+bUW56JhJaPYUv5PeU1gtn/8g7v64Yh8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=R+0cnxYhUKbJcNLfr/ptsRxftqWjqr+N0RKMorD7kgKEXvlfu0YTDuExrK1A4VMo5+57d4kMLtJrqzc0ox4Q86F2wm/Ca9wvYeVPEllT/+qgjJuyUurxaoVvuJRq0VF5WSou7oxjdCOR/EPyVMtwM0efhfviz9KqVUfc3YVV2is= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cqUeefee; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="cqUeefee" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1B385C116B1; Mon, 13 Oct 2025 15:32:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1760369543; bh=LS7Sv0eWZDH+bUW56JhJaPYUv5PeU1gtn/8g7v64Yh8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cqUeefeeCU+cuyJkfv1jkrbL6Jrdh8b1vzNE6fyqEOLixYYm1lkvcWQJudL1h9PAS Sm55ViffflQ9Fm86LNFauu2HV6zTWdYIgMclAI82l9/PatUhG2AjgZl2LugJM1ehJs 32qTbOQv5NRg5o0XjEQhYdI+Mm9EkDTliZapwisU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , David Ahern , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.17 284/563] net: dst: introduce dst->dev_rcu Date: Mon, 13 Oct 2025 16:42:25 +0200 Message-ID: <20251013144421.558676618@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251013144411.274874080@linuxfoundation.org> References: <20251013144411.274874080@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit caedcc5b6df1b2e2b5f39079e3369c1d4d5c5f50 ] Followup of commit 88fe14253e18 ("net: dst: add four helpers to annotate data-races around dst->dev"). We want to gradually add explicit RCU protection to dst->dev, including lockdep support. Add an union to alias dst->dev_rcu and dst->dev. Add dst_dev_net_rcu() helper. Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20250828195823.3958522-2-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- include/net/dst.h | 16 +++++++++++----- net/core/dst.c | 2 +- net/ipv4/route.c | 4 ++-- 3 files changed, 14 insertions(+), 8 deletions(-) diff --git a/include/net/dst.h b/include/net/dst.h index bab01363bb975..f8aa1239b4db6 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -24,7 +24,10 @@ struct sk_buff; struct dst_entry { - struct net_device *dev; + union { + struct net_device *dev; + struct net_device __rcu *dev_rcu; + }; struct dst_ops *ops; unsigned long _metrics; unsigned long expires; @@ -570,9 +573,12 @@ static inline struct net_device *dst_dev(const struct dst_entry *dst) static inline struct net_device *dst_dev_rcu(const struct dst_entry *dst) { - /* In the future, use rcu_dereference(dst->dev) */ - WARN_ON_ONCE(!rcu_read_lock_held()); - return READ_ONCE(dst->dev); + return rcu_dereference(dst->dev_rcu); +} + +static inline struct net *dst_dev_net_rcu(const struct dst_entry *dst) +{ + return dev_net_rcu(dst_dev_rcu(dst)); } static inline struct net_device *skb_dst_dev(const struct sk_buff *skb) @@ -592,7 +598,7 @@ static inline struct net *skb_dst_dev_net(const struct sk_buff *skb) static inline struct net *skb_dst_dev_net_rcu(const struct sk_buff *skb) { - return dev_net_rcu(skb_dst_dev(skb)); + return dev_net_rcu(skb_dst_dev_rcu(skb)); } struct dst_entry *dst_blackhole_check(struct dst_entry *dst, u32 cookie); diff --git a/net/core/dst.c b/net/core/dst.c index e2de8b68c41d3..e9d35f49c9e78 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -150,7 +150,7 @@ void dst_dev_put(struct dst_entry *dst) dst->ops->ifdown(dst, dev); WRITE_ONCE(dst->input, dst_discard); WRITE_ONCE(dst->output, dst_discard_out); - WRITE_ONCE(dst->dev, blackhole_netdev); + rcu_assign_pointer(dst->dev_rcu, blackhole_netdev); netdev_ref_replace(dev, blackhole_netdev, &dst->dev_tracker, GFP_ATOMIC); } diff --git a/net/ipv4/route.c b/net/ipv4/route.c index baa43e5966b19..97b96275a775d 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1026,7 +1026,7 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) return; rcu_read_lock(); - net = dev_net_rcu(dst_dev(dst)); + net = dst_dev_net_rcu(dst); if (mtu < net->ipv4.ip_rt_min_pmtu) { lock = true; mtu = min(old_mtu, net->ipv4.ip_rt_min_pmtu); @@ -1326,7 +1326,7 @@ static unsigned int ipv4_default_advmss(const struct dst_entry *dst) struct net *net; rcu_read_lock(); - net = dev_net_rcu(dst_dev(dst)); + net = dst_dev_net_rcu(dst); advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size, net->ipv4.ip_rt_min_advmss); rcu_read_unlock(); -- 2.51.0