From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sonic313-37.consmr.mail.ne1.yahoo.com (sonic313-37.consmr.mail.ne1.yahoo.com [66.163.185.60]) (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 28AFD2D9797 for ; Wed, 12 Nov 2025 07:35:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=66.163.185.60 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762932958; cv=none; b=cmQBLRGTKEkjSaJsav1y7uzHVnjmdwHw5QFuyhAIf1PCGzoNOlX3TUff44eFk5+wwUw4m1LW4/yj32kETVuAlaudPaUA2Huzjx+O54qgrnP4L2fG6dvtJMO2isqCXnfaHGNIzOC+BnZRByUQoqjGptxu+ncod9WzwaSafYmU5SE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762932958; c=relaxed/simple; bh=OyU7iNrKx66tOSbtWr9f5sbmRQ8+Kw4kZvZJKKMruR4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Oxh+KlsRkSwlQJF/7ucXZgu1lQ0FNTvd7CpfP1PQB3soQyA1ATRUs3XiyrzOZWazCfLdqm08g+0W1brpbkTfNRkFl3dSqlYhaQi1xVHKgTZYGQoRYTOwNNWq2xtHs7rmqMd7mMzsUcloEL6WgocGgwmd02Q7rSWB8xtanZKPTtE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=yahoo.com; spf=pass smtp.mailfrom=yahoo.com; dkim=pass (2048-bit key) header.d=yahoo.com header.i=@yahoo.com header.b=Pts68ZZN; arc=none smtp.client-ip=66.163.185.60 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=yahoo.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=yahoo.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=yahoo.com header.i=@yahoo.com header.b="Pts68ZZN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1762932955; bh=CH0G10o9ovK4ErRUQI3fyw6Jpp8tKHNbeB7uxEnNREk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From:Subject:Reply-To; b=Pts68ZZNDz/C2ngjRB8G4u09AQs54fXtJMKQrnEYwbMR83x0s200tZff8oRQZzc+FUr1udeFhCeFxSLuW9gImeZPdYcflVTjxnAVRqMn2pbdsGCcwSXZB8gXcW/4HNGMuvRFTwD+KxJuoh8s26G+I6lo1FjqLdo/nEwg5Pcu/0j7Ej7c9lnLdgfiY5palh9CVHM221lWxZsuHwpRDPqOOSYgFqmbg0viKpmo29m/UJ5lVwC0rauXPAcoLCuoLvMQX/lTFRDwv/GbCC5wrwClVoVvXEMvpyZivMn1xTq5SG3m2+Um9esUFwJjDEuTY1E24fcRTc8H/7nax7G8XiMsxg== X-SONIC-DKIM-SIGN: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1762932955; bh=owevqugNSvm/dXvu43EsRAEe2S9zwXcWRpEnXZffAJA=; h=X-Sonic-MF:From:To:Subject:Date:From:Subject; b=ZMSORxfKzq3JcHBH39tqE2kz+G5rMM9DdJtjOGld85niZGeSyNGKBsB4kCEkRpPyjSqZN7KHMMKAEJQXSHrm6t+zKGakwO3Vml+1VKRGGv4u9Vecx3IfeQaGUWuxDnO2NMKEMo19k47Yk8p963AMHJ9tUKhKFAnEf4JBL5WuOmoOahGYe7KFan9yAw/dxq/2z1g61GM6dAE0l8e2y7GDrWiLLS5dNA/6IJjxJBJgR5WYOzSvaY3jJGj90i0stPo8y/pZ3fy3zzcvUOo3XD1qk9fedji9GZRWEzPzmmdaqIppzGcXtIsE+/2/TPc/gAj9L6ZXLytJHpqkDUMJ2puX4Q== X-YMail-OSG: zN6d2HAVM1m9hflmCMiXD2TsqqkaW7Fop.SMyMFbHfwRbkMeMoqgspsST2hPkY9 8ueCBzPNpq8Of7DLT1EPj0dtsbUO9QijbvzKCVU_bUW6mkNQU1OmkAcmKFIuyIaT55DVmFb21GrP RQ0tAlgth7.Bl_S4yJozqRY6sPAVRnd2JjfQcnJaZNAlulkEpp4WMZ8pYrgwR5yCKe4BCbizoq3h 4UZMYiShpfLvjcUA8tjv7QEL3ufqQ9x8UmYAuYcQmHGami_3XMw43aemVrz3AYGTHWP429cczRso sXYIXqutVtBLnA3YgaAUbTZvZq9LEBxq5TWU0BaBoWeRBT4l5Ubr55AVSIVKEZhb.eCgg5nTogA0 Vzc4KipUz2ulKMIAS_fzHb_LJxWeENJ3BWydIr3KRtmcwpHIox.YlLQxFdVidjVxkyEvDQ0ujjdJ 3__4aM2fFvD_ytoM3zk_5TkAYsxR2RoOUqwDgjaWEPRewlD05gDD9A6IgMRiFIi4TA.hlGvvri8i GXtsreH1hkTBeqpHAkWXLkQV4dCZ.JFTrh5fVqRrmf5pwpATAw6Voikd0orDvdKohXoGVYT9k4sz EuJhw07uglwi3oIpBry76n_WurGPYwqdXZOSt9CINoIntMBtICt5zJ1Pg30iGnJKd1E9EHOOcUHc WWaWYTuNwJ.3gdrqahnNxtAv7cSAzYOu_xbKGWBXXXLn7B4vASzpECzwpE6SqnO4ArMFAwVpjTi1 _9ZR.pSXaXVFsQDDDVOLhEoE97oASaVVEo_4_eyoFQwTH8I2uSytiSARxi6cuQyvW_Dt8kn_aaYD eedSy9ZDROno0Zp3ZyeY4avzo4WmIckEmgE2sVJhK87Ha1TZ7dAEGG06iYFd3ZnmNizIjpR.k3Il SjKvEOyyFfzyia.JbAQjLBozPi4ZTT.zwJhiL90psgwGPokhcYGxV7Qjpivx0..KY2.kEJgQ_JN. A89odhAJYWwpLIu_vfRzigDR_qrlS74CWFOS53_l6vfUz.sy.FD97A0m8WxAqOW0O5P5gAcsjdub Z.6vDv7j5F4s1ZZK0_cWABI.w0c2MkVClYqCLZt544pu1OpaoEMRCn7ZCLnb0Oz6XdoikYEdmqTI 5XX_R_OPq0xNjln6A3PJOQ_.dybS3CA2MC9QaE30GrwkwPsEWxFdLtdniLgI5IALenzkfzRvyb54 cfLxZxp2GnaVwcshyhqnCkCJ3_TcPyLvD7RI_dRHgIIzCW_QGVcDKaccLUQzudFohdcxqQYDbHk2 7hlDu4FW5i2V7Z7iQSn4a_ZSwNKYLWI25kLL_D5x3dKy9irBRnKtKIWCj4qEVMJ5pV3Rmh1yVKE4 cULWB.6JI7xINCvcDE6Y93oM9Sm0Vc4tDhTUewV_nSBmM4vq8.QkT_YZ.Us6zjHoNk_dtgemgfYu bzYaN0JC9JZ5jkJTxRm3Cgsy_oFpZ0S_8iZqZlq.M1A8u5mC9Eq7fzF_Yx9ED415wuHhoZkVqkqI axIASGzMRipWgvY4VfNFKPG2QBY21ieLmX2Q4YaYEcuCl_fijHC0z.b.UQPLEWhv8ie4BtGy4wva X2azNo89uW86HvwL4v8wQu6INs1qggT9Bc0tLIHISstSjQWidlriLojRdcvZ1FIAUVnsC3wt_1o8 hxQkHWH7CoKiJaTkgNoDEKP94obmWe7O.5efE1fG4txGyRlWesnhE1l7vfrLLgBwhx6EIKD6Yhze FlI2DrbghvruSv8mz6OJnSI3AQ1ztPjL_q9LhFIPxDufmBZtQ4DWp_UbjWLdSoX3wbfygJQwVScZ Va3RjSRkuzKQFd4srgZRRWdD9_86Y7iY7wM9kq2mjBWAo2Fni54lNJdIPfWvjgAmxTAHIniwjDtR DrzutDO4sJrgbhZHQakj5A0ZlsokIvmgqyRcnDGN4o3AQnP9BuaShPm4da9BMXvjY9qDpLqNx5i6 TmTFSMCROhaU05uBBTCdXkedolRWn1fkylQiS43R.gAkMT5ya0bV9stHcxntXYjrArkrzRnhlM9. tNJN35xspHwXc799NWE2m9XnKx6W1HQfX941yxntWhUy2Yvb2ddDRjZh37QW70lmkReL2E2puM9Y 8b1LiFEu4vav5bzZH83LStgba4wtSWTmMgPwFz476DXRCh5u0itX6gdiDRK03eRX8.qdrzA74wNB _VmBbGHJ.0sOTAPaAekBes2RPr1xGIqz4gx01Jvdg8FcS8bvxoM6ofPENVuxT0nzj6SdJa8tZiA6 rS_MsJ4rMqkw- X-Sonic-MF: X-Sonic-ID: f3893782-864e-449d-8175-4b2b5ba3e303 Received: from sonic.gate.mail.ne1.yahoo.com by sonic313.consmr.mail.ne1.yahoo.com with HTTP; Wed, 12 Nov 2025 07:35:55 +0000 Received: by hermes--production-ir2-5fcfdd8d7f-gtwf2 (Yahoo Inc. Hermes SMTP Server) with ESMTPA ID 8a3972250952fefb5c72bc783ca56e47; Wed, 12 Nov 2025 07:33:53 +0000 (UTC) From: Marek Mietus To: netdev@vger.kernel.org, sd@queasysnail.net, kuba@kernel.org Cc: Marek Mietus Subject: [PATCH net-next v4 10/14] net: tunnel: convert ip_md_tunnel_xmit to use a noref dst when possible Date: Wed, 12 Nov 2025 08:33:20 +0100 Message-ID: <20251112073324.5301-1-mmietus97@yahoo.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251112072720.5076-1-mmietus97@yahoo.com> References: <20251112072720.5076-1-mmietus97@yahoo.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit ip_md_tunnel_xmit unnecessarily references the dst_entry from the dst_cache when interacting with the cache. Reduce this overhead by avoiding the redundant refcount increments. This is only possible in flows where the cache is used. Otherwise, we fall-back to a referenced dst. This change is safe since ipv4 supports noref xmit under RCU which is already the case for ip_md_tunnel_xmit. Signed-off-by: Marek Mietus --- net/ipv4/ip_tunnel.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c index 6aa045793048..323d085cc377 100644 --- a/net/ipv4/ip_tunnel.c +++ b/net/ipv4/ip_tunnel.c @@ -578,6 +578,7 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, const struct iphdr *inner_iph; struct rtable *rt = NULL; struct flowi4 fl4; + dstref_t dstref; __be16 df = 0; u8 tos, ttl; bool use_cache; @@ -608,20 +609,26 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, goto tx_error; use_cache = ip_tunnel_dst_cache_usable(skb, tun_info); - if (use_cache) - rt = dst_cache_get_ip4(&tun_info->dst_cache, &fl4.saddr); + if (use_cache) { + rt = dst_cache_get_ip4_rcu(&tun_info->dst_cache, &fl4.saddr); + dstref = dst_to_dstref_noref(&rt->dst); + } if (!rt) { rt = ip_route_output_key(tunnel->net, &fl4); if (IS_ERR(rt)) { DEV_STATS_INC(dev, tx_carrier_errors); goto tx_error; } - if (use_cache) - dst_cache_set_ip4(&tun_info->dst_cache, &rt->dst, - fl4.saddr); + if (use_cache) { + dst_cache_steal_ip4(&tun_info->dst_cache, &rt->dst, + fl4.saddr); + dstref = dst_to_dstref_noref(&rt->dst); + } else { + dstref = dst_to_dstref(&rt->dst); + } } if (rt->dst.dev == dev) { - ip_rt_put(rt); + dstref_drop(dstref); DEV_STATS_INC(dev, collisions); goto tx_error; } @@ -630,7 +637,7 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, df = htons(IP_DF); if (tnl_update_pmtu(dev, skb, rt, df, inner_iph, tunnel_hlen, key->u.ipv4.dst, true)) { - ip_rt_put(rt); + dstref_drop(dstref); goto tx_error; } @@ -647,13 +654,13 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, headroom += LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len; if (skb_cow_head(skb, headroom)) { - ip_rt_put(rt); + dstref_drop(dstref); goto tx_dropped; } ip_tunnel_adj_headroom(dev, headroom); - iptunnel_xmit(NULL, dst_to_dstref(&rt->dst), skb, fl4.saddr, fl4.daddr, proto, tos, ttl, + iptunnel_xmit(NULL, dstref, skb, fl4.saddr, fl4.daddr, proto, tos, ttl, df, !net_eq(tunnel->net, dev_net(dev)), 0); return; tx_error: -- 2.51.0