From nobody Mon Nov 25 17:44:56 2024 Received: from serv108.segi.ulg.ac.be (serv108.segi.ulg.ac.be [139.165.32.111]) (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 BFB58212177; Fri, 25 Oct 2024 13:46:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=139.165.32.111 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729863987; cv=none; b=HAIxHz9baDDZjFI1j7doZrPtLWAuqOvg4AFYLU6ObZkrpta91XYjeFMR4gbOWN8kBcz6UXCuggpAdFIBdYWl7ol7jisafRez3728RDO32XHmXJ/2WzDboBaVWJ/7emoSK3rrOKmancKnvREFiyYkq3wJF6wQbB82IQofBkCMNFU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729863987; c=relaxed/simple; bh=pN5S/suqrVBmUuOOhlG641kV76MVLuZyxF3UxYpKWJM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=IeDIzHPjGGs2piKpP4p02s9W2ndGgs4zTXg227JU2Jr0REj72e5f/DulaaekIuG2mXdVwcv5+97OluZJ1oXCmPDTJ8GHANCQ0L5+JRVY+5L9pGP1fT8KqQkBaQGqX1Ozjhs+akkGJMDG6P+F5CnOoz47WoWuDzdRZFmjxiifKyc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=uliege.be; spf=pass smtp.mailfrom=uliege.be; dkim=pass (2048-bit key) header.d=uliege.be header.i=@uliege.be header.b=0u6jS3/u; arc=none smtp.client-ip=139.165.32.111 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=uliege.be Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=uliege.be Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=uliege.be header.i=@uliege.be header.b="0u6jS3/u" Received: from localhost.localdomain (220.24-245-81.adsl-dyn.isp.belgacom.be [81.245.24.220]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by serv108.segi.ulg.ac.be (Postfix) with ESMTPSA id A96AC200EEC4; Fri, 25 Oct 2024 15:37:49 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 serv108.segi.ulg.ac.be A96AC200EEC4 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uliege.be; s=ulg20190529; t=1729863469; bh=1+tgB7eC8476UFHHG9DorVn20PbINOrYtk0wudgCZhA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0u6jS3/u+5aFCoCVC8vpi0PKT8EEk+Qi/zedGzpgSz+VMpSY9yuWCZ+Mi+SEFrtR/ Qt1D1M1NmZQuRviwumzhj7fNCOqqaBhxIH+drhkLhstIKMf8Wz2idZA/OHGYxWopGQ G/jvoLqJ12eNfqLeUmjXnv3bDuNu8gw0ZsTRJnhtcPJpce4AWF0JjoEN+F2jX/Ba+3 QxMsWtALS7/6+yjLuEKULusC9i2k1YZF8aLuuQL8FOemZl8Uw8wVrI7Xnqs5T1DQul rECe0MyBq+ftV/XKzADn1P09xfHsAonURjWX1xaenkoEFSTm61ZlbWcqS91RPaVZ9X 8MUimQdGxSo8Q== From: Justin Iurman To: netdev@vger.kernel.org Cc: davem@davemloft.net, dsahern@kernel.org, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, linux-kernel@vger.kernel.org, justin.iurman@uliege.be Subject: [PATCH net-next 1/3] net: ipv6: ioam6_iptunnel: mitigate 2-realloc issue Date: Fri, 25 Oct 2024 15:37:25 +0200 Message-Id: <20241025133727.27742-2-justin.iurman@uliege.be> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20241025133727.27742-1-justin.iurman@uliege.be> References: <20241025133727.27742-1-justin.iurman@uliege.be> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This patch mitigates the two-reallocations issue with ioam6_iptunnel by providing the dst_entry (in the cache) to the first call to skb_cow_head(). As a result, the very first iteration would still trigger two reallocations (i.e., empty cache), while next iterations would only trigger a single reallocation. Performance tests before/after applying this patch, which clearly shows the improvement: - inline mode: - before: https://ibb.co/LhQ8V63 - after: https://ibb.co/x5YT2bS - encap mode: - before: https://ibb.co/3Cjm5m0 - after: https://ibb.co/TwpsxTC - encap mode with tunsrc: - before: https://ibb.co/Gpy9QPg - after: https://ibb.co/PW1bZFT This patch also fixes an incorrect behavior: after the insertion, the second call to skb_cow_head() makes sure that the dev has enough headroom in the skb for layer 2 and stuff. In that case, the "old" dst_entry was used, which is now fixed. After discussing with Paolo, it appears that both patches can be merged into a single one -this one- (for the sake of readability) and target net-next. Signed-off-by: Justin Iurman --- net/ipv6/ioam6_iptunnel.c | 84 ++++++++++++++++++++------------------- 1 file changed, 43 insertions(+), 41 deletions(-) diff --git a/net/ipv6/ioam6_iptunnel.c b/net/ipv6/ioam6_iptunnel.c index beb6b4cfc551..da79055fc02a 100644 --- a/net/ipv6/ioam6_iptunnel.c +++ b/net/ipv6/ioam6_iptunnel.c @@ -255,14 +255,16 @@ static int ioam6_do_fill(struct net *net, struct sk_b= uff *skb) } =20 static int ioam6_do_inline(struct net *net, struct sk_buff *skb, - struct ioam6_lwt_encap *tuninfo) + struct ioam6_lwt_encap *tuninfo, + struct dst_entry *dst) { struct ipv6hdr *oldhdr, *hdr; int hdrlen, err; =20 hdrlen =3D (tuninfo->eh.hdrlen + 1) << 3; =20 - err =3D skb_cow_head(skb, hdrlen + skb->mac_len); + err =3D skb_cow_head(skb, hdrlen + (!dst ? skb->mac_len + : LL_RESERVED_SPACE(dst->dev))); if (unlikely(err)) return err; =20 @@ -293,16 +295,17 @@ static int ioam6_do_encap(struct net *net, struct sk_= buff *skb, struct ioam6_lwt_encap *tuninfo, bool has_tunsrc, struct in6_addr *tunsrc, - struct in6_addr *tundst) + struct in6_addr *tundst, + struct dst_entry *dst) { - struct dst_entry *dst =3D skb_dst(skb); struct ipv6hdr *hdr, *inner_hdr; int hdrlen, len, err; =20 hdrlen =3D (tuninfo->eh.hdrlen + 1) << 3; len =3D sizeof(*hdr) + hdrlen; =20 - err =3D skb_cow_head(skb, len + skb->mac_len); + err =3D skb_cow_head(skb, len + (!dst ? skb->mac_len + : LL_RESERVED_SPACE(dst->dev))); if (unlikely(err)) return err; =20 @@ -326,7 +329,7 @@ static int ioam6_do_encap(struct net *net, struct sk_bu= ff *skb, if (has_tunsrc) memcpy(&hdr->saddr, tunsrc, sizeof(*tunsrc)); else - ipv6_dev_get_saddr(net, dst->dev, &hdr->daddr, + ipv6_dev_get_saddr(net, skb_dst(skb)->dev, &hdr->daddr, IPV6_PREFER_SRC_PUBLIC, &hdr->saddr); =20 skb_postpush_rcsum(skb, hdr, len); @@ -336,7 +339,7 @@ static int ioam6_do_encap(struct net *net, struct sk_bu= ff *skb, =20 static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *= skb) { - struct dst_entry *dst =3D skb_dst(skb); + struct dst_entry *dst, *orig_dst =3D skb_dst(skb); struct in6_addr orig_daddr; struct ioam6_lwt *ilwt; int err =3D -EINVAL; @@ -345,7 +348,7 @@ static int ioam6_output(struct net *net, struct sock *s= k, struct sk_buff *skb) if (skb->protocol !=3D htons(ETH_P_IPV6)) goto drop; =20 - ilwt =3D ioam6_lwt_state(dst->lwtstate); + ilwt =3D ioam6_lwt_state(orig_dst->lwtstate); =20 /* Check for insertion frequency (i.e., "k over n" insertions) */ pkt_cnt =3D atomic_fetch_inc(&ilwt->pkt_cnt); @@ -354,6 +357,10 @@ static int ioam6_output(struct net *net, struct sock *= sk, struct sk_buff *skb) =20 orig_daddr =3D ipv6_hdr(skb)->daddr; =20 + local_bh_disable(); + dst =3D dst_cache_get(&ilwt->cache); + local_bh_enable(); + switch (ilwt->mode) { case IOAM6_IPTUNNEL_MODE_INLINE: do_inline: @@ -361,7 +368,7 @@ static int ioam6_output(struct net *net, struct sock *s= k, struct sk_buff *skb) if (ipv6_hdr(skb)->nexthdr =3D=3D NEXTHDR_HOP) goto out; =20 - err =3D ioam6_do_inline(net, skb, &ilwt->tuninfo); + err =3D ioam6_do_inline(net, skb, &ilwt->tuninfo, dst); if (unlikely(err)) goto drop; =20 @@ -371,7 +378,7 @@ static int ioam6_output(struct net *net, struct sock *s= k, struct sk_buff *skb) /* Encapsulation (ip6ip6) */ err =3D ioam6_do_encap(net, skb, &ilwt->tuninfo, ilwt->has_tunsrc, &ilwt->tunsrc, - &ilwt->tundst); + &ilwt->tundst, dst); if (unlikely(err)) goto drop; =20 @@ -389,45 +396,40 @@ static int ioam6_output(struct net *net, struct sock = *sk, struct sk_buff *skb) goto drop; } =20 - err =3D skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); - if (unlikely(err)) - goto drop; + if (unlikely(!dst)) { + struct ipv6hdr *hdr =3D ipv6_hdr(skb); + struct flowi6 fl6; + + memset(&fl6, 0, sizeof(fl6)); + fl6.daddr =3D hdr->daddr; + fl6.saddr =3D hdr->saddr; + fl6.flowlabel =3D ip6_flowinfo(hdr); + fl6.flowi6_mark =3D skb->mark; + fl6.flowi6_proto =3D hdr->nexthdr; + + dst =3D ip6_route_output(net, NULL, &fl6); + if (dst->error) { + err =3D dst->error; + dst_release(dst); + goto drop; + } =20 - if (!ipv6_addr_equal(&orig_daddr, &ipv6_hdr(skb)->daddr)) { local_bh_disable(); - dst =3D dst_cache_get(&ilwt->cache); + dst_cache_set_ip6(&ilwt->cache, dst, &fl6.saddr); local_bh_enable(); =20 - if (unlikely(!dst)) { - struct ipv6hdr *hdr =3D ipv6_hdr(skb); - struct flowi6 fl6; - - memset(&fl6, 0, sizeof(fl6)); - fl6.daddr =3D hdr->daddr; - fl6.saddr =3D hdr->saddr; - fl6.flowlabel =3D ip6_flowinfo(hdr); - fl6.flowi6_mark =3D skb->mark; - fl6.flowi6_proto =3D hdr->nexthdr; - - dst =3D ip6_route_output(net, NULL, &fl6); - if (dst->error) { - err =3D dst->error; - dst_release(dst); - goto drop; - } - - local_bh_disable(); - dst_cache_set_ip6(&ilwt->cache, dst, &fl6.saddr); - local_bh_enable(); - } + err =3D skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); + if (unlikely(err)) + goto drop; + } =20 - skb_dst_drop(skb); - skb_dst_set(skb, dst); + skb_dst_drop(skb); + skb_dst_set(skb, dst); =20 + if (!ipv6_addr_equal(&orig_daddr, &ipv6_hdr(skb)->daddr)) return dst_output(net, sk, skb); - } out: - return dst->lwtstate->orig_output(net, sk, skb); + return orig_dst->lwtstate->orig_output(net, sk, skb); drop: kfree_skb(skb); return err; --=20 2.34.1 From nobody Mon Nov 25 17:44:56 2024 Received: from serv108.segi.ulg.ac.be (serv108.segi.ulg.ac.be [139.165.32.111]) (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 DCA5E3A8D2; Fri, 25 Oct 2024 13:46:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=139.165.32.111 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729863987; cv=none; b=r44Yi2n9hXR0kHAW2aexjI6LNDt2QK3W/9Qbv14lg/mRzaJpsUZR3kbxZvookQUYIh2/HSyMXpSJQrRXJIMFcHb7Mk4VGAyorG8OznQWsPTTGtmRfJa5CLzL437ktNXtkph5J8qIITg83RDn8miV/LDVFt35qFTSjnW69y9DuBw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729863987; c=relaxed/simple; bh=wmDMRmRySC2chPRGrnkGc4c6bRSIRdYPcSiPv2a/C9M=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=BhsU+BUJV2FLQTqNRwJMG+SXzbLunByAuA7zDde27QMU8KINpr8egcojLsMtw9jywCuBCGdRCy0h8I31TtCXDyhJCfQmWwRHJF2W6xJPSSNH8QtkVQ8ELqefWhmiEssHB4x+phcT151GJvAlgSb4J66HECgZck2AG13XJqyxl90= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=uliege.be; spf=pass smtp.mailfrom=uliege.be; dkim=pass (2048-bit key) header.d=uliege.be header.i=@uliege.be header.b=J9eWUcBh; arc=none smtp.client-ip=139.165.32.111 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=uliege.be Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=uliege.be Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=uliege.be header.i=@uliege.be header.b="J9eWUcBh" Received: from localhost.localdomain (220.24-245-81.adsl-dyn.isp.belgacom.be [81.245.24.220]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by serv108.segi.ulg.ac.be (Postfix) with ESMTPSA id DE065200EEC7; Fri, 25 Oct 2024 15:37:49 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 serv108.segi.ulg.ac.be DE065200EEC7 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uliege.be; s=ulg20190529; t=1729863470; bh=L3upFZWTjEaF8j/4kVwYHzAsNl63IflPSspzcmSrI70=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=J9eWUcBhAOlvBdOaROcnTNWcHMFuikBlxLarX3wtAtKK9GCo1PJ134ZN0pvYmtFGc WFxVySpoZLUtEUdlJN7o/DvjvRO9YeexM01izmpGqLQd5MyiYHzsRVsqA8DeeeUoFw 9juvwJcMmonmErPdhqHyDZf396Gy+lWoNwidzqjdAYhHAfzB8DWmY+4LHMGr6VIGLe 11o9luy2UNKXGOjKOwfVFeHMN8uABrEN7WjBssY6od92OjyIglk+6GqP6cKJJ4bDca HiEcmV3FRpkhjAUWKKNDweQCIi9lsMskwhP3wgIk4SiE5mmhJlFc2928QYnEZ+ltSu hsz4jGMr731FQ== From: Justin Iurman To: netdev@vger.kernel.org Cc: davem@davemloft.net, dsahern@kernel.org, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, linux-kernel@vger.kernel.org, justin.iurman@uliege.be Subject: [PATCH net-next 2/3] net: ipv6: seg6_iptunnel: mitigate 2-realloc issue Date: Fri, 25 Oct 2024 15:37:26 +0200 Message-Id: <20241025133727.27742-3-justin.iurman@uliege.be> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20241025133727.27742-1-justin.iurman@uliege.be> References: <20241025133727.27742-1-justin.iurman@uliege.be> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This patch mitigates the two-reallocations issue with seg6_iptunnel by providing the dst_entry (in the cache) to the first call to skb_cow_head(). As a result, the very first iteration would still trigger two reallocations (i.e., empty cache), while next iterations would only trigger a single reallocation. Performance tests before/after applying this patch, which clearly shows the improvement: - before: https://ibb.co/3Cg4sNH - after: https://ibb.co/8rQ350r Signed-off-by: Justin Iurman --- net/ipv6/seg6_iptunnel.c | 103 ++++++++++++++++++++++----------------- 1 file changed, 58 insertions(+), 45 deletions(-) diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c index 098632adc9b5..7789a31db355 100644 --- a/net/ipv6/seg6_iptunnel.c +++ b/net/ipv6/seg6_iptunnel.c @@ -127,8 +127,14 @@ static __be32 seg6_make_flowlabel(struct net *net, str= uct sk_buff *skb, /* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH= */ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int p= roto) { - struct dst_entry *dst =3D skb_dst(skb); - struct net *net =3D dev_net(dst->dev); + return __seg6_do_srh_encap(skb, osrh, proto, NULL); +} +EXPORT_SYMBOL_GPL(seg6_do_srh_encap); + +int __seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, + int proto, struct dst_entry *dst) +{ + struct net *net =3D dev_net(skb_dst(skb)->dev); struct ipv6hdr *hdr, *inner_hdr; struct ipv6_sr_hdr *isrh; int hdrlen, tot_len, err; @@ -137,7 +143,8 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_= sr_hdr *osrh, int proto) hdrlen =3D (osrh->hdrlen + 1) << 3; tot_len =3D hdrlen + sizeof(*hdr); =20 - err =3D skb_cow_head(skb, tot_len + skb->mac_len); + err =3D skb_cow_head(skb, tot_len + (!dst ? skb->mac_len + : LL_RESERVED_SPACE(dst->dev))); if (unlikely(err)) return err; =20 @@ -181,7 +188,7 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_= sr_hdr *osrh, int proto) isrh->nexthdr =3D proto; =20 hdr->daddr =3D isrh->segments[isrh->first_segment]; - set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr); + set_tun_src(net, skb_dst(skb)->dev, &hdr->daddr, &hdr->saddr); =20 #ifdef CONFIG_IPV6_SEG6_HMAC if (sr_has_hmac(isrh)) { @@ -197,15 +204,14 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv= 6_sr_hdr *osrh, int proto) =20 return 0; } -EXPORT_SYMBOL_GPL(seg6_do_srh_encap); =20 /* encapsulate an IPv6 packet within an outer IPv6 header with reduced SRH= */ static int seg6_do_srh_encap_red(struct sk_buff *skb, - struct ipv6_sr_hdr *osrh, int proto) + struct ipv6_sr_hdr *osrh, int proto, + struct dst_entry *dst) { __u8 first_seg =3D osrh->first_segment; - struct dst_entry *dst =3D skb_dst(skb); - struct net *net =3D dev_net(dst->dev); + struct net *net =3D dev_net(skb_dst(skb)->dev); struct ipv6hdr *hdr, *inner_hdr; int hdrlen =3D ipv6_optlen(osrh); int red_tlv_offset, tlv_offset; @@ -230,7 +236,8 @@ static int seg6_do_srh_encap_red(struct sk_buff *skb, =20 tot_len =3D red_hdrlen + sizeof(struct ipv6hdr); =20 - err =3D skb_cow_head(skb, tot_len + skb->mac_len); + err =3D skb_cow_head(skb, tot_len + (!dst ? skb->mac_len + : LL_RESERVED_SPACE(dst->dev))); if (unlikely(err)) return err; =20 @@ -263,7 +270,7 @@ static int seg6_do_srh_encap_red(struct sk_buff *skb, if (skip_srh) { hdr->nexthdr =3D proto; =20 - set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr); + set_tun_src(net, skb_dst(skb)->dev, &hdr->daddr, &hdr->saddr); goto out; } =20 @@ -299,7 +306,7 @@ static int seg6_do_srh_encap_red(struct sk_buff *skb, =20 srcaddr: isrh->nexthdr =3D proto; - set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr); + set_tun_src(net, skb_dst(skb)->dev, &hdr->daddr, &hdr->saddr); =20 #ifdef CONFIG_IPV6_SEG6_HMAC if (unlikely(!skip_srh && sr_has_hmac(isrh))) { @@ -319,6 +326,13 @@ static int seg6_do_srh_encap_red(struct sk_buff *skb, =20 /* insert an SRH within an IPv6 packet, just after the IPv6 header */ int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh) +{ + return __seg6_do_srh_inline(skb, osrh, NULL); +} +EXPORT_SYMBOL_GPL(seg6_do_srh_inline); + +int __seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, + struct dst_entry *dst) { struct ipv6hdr *hdr, *oldhdr; struct ipv6_sr_hdr *isrh; @@ -326,7 +340,8 @@ int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6= _sr_hdr *osrh) =20 hdrlen =3D (osrh->hdrlen + 1) << 3; =20 - err =3D skb_cow_head(skb, hdrlen + skb->mac_len); + err =3D skb_cow_head(skb, hdrlen + (!dst ? skb->mac_len + : LL_RESERVED_SPACE(dst->dev))); if (unlikely(err)) return err; =20 @@ -369,22 +384,20 @@ int seg6_do_srh_inline(struct sk_buff *skb, struct ip= v6_sr_hdr *osrh) =20 return 0; } -EXPORT_SYMBOL_GPL(seg6_do_srh_inline); =20 -static int seg6_do_srh(struct sk_buff *skb) +static int seg6_do_srh(struct sk_buff *skb, struct dst_entry *dst) { - struct dst_entry *dst =3D skb_dst(skb); struct seg6_iptunnel_encap *tinfo; int proto, err =3D 0; =20 - tinfo =3D seg6_encap_lwtunnel(dst->lwtstate); + tinfo =3D seg6_encap_lwtunnel(skb_dst(skb)->lwtstate); =20 switch (tinfo->mode) { case SEG6_IPTUN_MODE_INLINE: if (skb->protocol !=3D htons(ETH_P_IPV6)) return -EINVAL; =20 - err =3D seg6_do_srh_inline(skb, tinfo->srh); + err =3D __seg6_do_srh_inline(skb, tinfo->srh, dst); if (err) return err; break; @@ -402,9 +415,9 @@ static int seg6_do_srh(struct sk_buff *skb) return -EINVAL; =20 if (tinfo->mode =3D=3D SEG6_IPTUN_MODE_ENCAP) - err =3D seg6_do_srh_encap(skb, tinfo->srh, proto); + err =3D __seg6_do_srh_encap(skb, tinfo->srh, proto, dst); else - err =3D seg6_do_srh_encap_red(skb, tinfo->srh, proto); + err =3D seg6_do_srh_encap_red(skb, tinfo->srh, proto, dst); =20 if (err) return err; @@ -425,11 +438,11 @@ static int seg6_do_srh(struct sk_buff *skb) skb_push(skb, skb->mac_len); =20 if (tinfo->mode =3D=3D SEG6_IPTUN_MODE_L2ENCAP) - err =3D seg6_do_srh_encap(skb, tinfo->srh, - IPPROTO_ETHERNET); + err =3D __seg6_do_srh_encap(skb, tinfo->srh, + IPPROTO_ETHERNET, dst); else err =3D seg6_do_srh_encap_red(skb, tinfo->srh, - IPPROTO_ETHERNET); + IPPROTO_ETHERNET, dst); =20 if (err) return err; @@ -453,36 +466,37 @@ static int seg6_input_finish(struct net *net, struct = sock *sk, static int seg6_input_core(struct net *net, struct sock *sk, struct sk_buff *skb) { - struct dst_entry *orig_dst =3D skb_dst(skb); - struct dst_entry *dst =3D NULL; + struct dst_entry *dst; struct seg6_lwt *slwt; int err; =20 - err =3D seg6_do_srh(skb); - if (unlikely(err)) - goto drop; - - slwt =3D seg6_lwt_lwtunnel(orig_dst->lwtstate); + slwt =3D seg6_lwt_lwtunnel(skb_dst(skb)->lwtstate); =20 local_bh_disable(); dst =3D dst_cache_get(&slwt->cache); + local_bh_enable(); + + err =3D seg6_do_srh(skb, dst); + if (unlikely(err)) + goto drop; =20 if (!dst) { ip6_route_input(skb); dst =3D skb_dst(skb); if (!dst->error) { + local_bh_disable(); dst_cache_set_ip6(&slwt->cache, dst, &ipv6_hdr(skb)->saddr); + local_bh_enable(); } + + err =3D skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); + if (unlikely(err)) + goto drop; } else { skb_dst_drop(skb); skb_dst_set(skb, dst); } - local_bh_enable(); - - err =3D skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); - if (unlikely(err)) - goto drop; =20 if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled)) return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, @@ -523,21 +537,20 @@ static int seg6_input(struct sk_buff *skb) static int seg6_output_core(struct net *net, struct sock *sk, struct sk_buff *skb) { - struct dst_entry *orig_dst =3D skb_dst(skb); - struct dst_entry *dst =3D NULL; + struct dst_entry *dst; struct seg6_lwt *slwt; int err; =20 - err =3D seg6_do_srh(skb); - if (unlikely(err)) - goto drop; - - slwt =3D seg6_lwt_lwtunnel(orig_dst->lwtstate); + slwt =3D seg6_lwt_lwtunnel(skb_dst(skb)->lwtstate); =20 local_bh_disable(); dst =3D dst_cache_get(&slwt->cache); local_bh_enable(); =20 + err =3D seg6_do_srh(skb, dst); + if (unlikely(err)) + goto drop; + if (unlikely(!dst)) { struct ipv6hdr *hdr =3D ipv6_hdr(skb); struct flowi6 fl6; @@ -559,15 +572,15 @@ static int seg6_output_core(struct net *net, struct s= ock *sk, local_bh_disable(); dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr); local_bh_enable(); + + err =3D skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); + if (unlikely(err)) + goto drop; } =20 skb_dst_drop(skb); skb_dst_set(skb, dst); =20 - err =3D skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); - if (unlikely(err)) - goto drop; - if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled)) return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, net, sk, skb, NULL, skb_dst(skb)->dev, dst_output); --=20 2.34.1 From nobody Mon Nov 25 17:44:56 2024 Received: from serv108.segi.ulg.ac.be (serv108.segi.ulg.ac.be [139.165.32.111]) (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 DC9DB1DFF5; Fri, 25 Oct 2024 13:46:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=139.165.32.111 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729863988; cv=none; b=CPU9Y9rfcZFgMQf9IwLqX4r4FKG48SnqpEIC/hAsoEQvhlMjemZrydCeXsCVTQhmsm0MNwgcOjm8+F1W3IfQZ5BzdTBA+S3HGRMDJaBtezmivuTwg+64+nLVMb5DQ1vZfSZV34YDf0DbAsCFzNgvi4yuCCns6HqDAzA32c4dxys= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729863988; c=relaxed/simple; bh=Xn/iAWW87UHsfh2vqmaJ638Sc5zPdn891175iWHYZQg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=G37O6ZjENxl2Jpx2ObQpjYv2UjT6HSBp0pYjHiSAUwP6PXJhHtn87/LsTLjismryHKD9N1iNpj1UqLquGM4HYlOfGaROs+Cs3LSrhw7cVG3M1rd9hoFH+tBV4W3DhQSBtAtiY4TD+IOwMqF/ssDsldBHYQfAH0U/IqUOrKFKC4U= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=uliege.be; spf=pass smtp.mailfrom=uliege.be; dkim=pass (2048-bit key) header.d=uliege.be header.i=@uliege.be header.b=R9VWmsMk; arc=none smtp.client-ip=139.165.32.111 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=uliege.be Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=uliege.be Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=uliege.be header.i=@uliege.be header.b="R9VWmsMk" Received: from localhost.localdomain (220.24-245-81.adsl-dyn.isp.belgacom.be [81.245.24.220]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by serv108.segi.ulg.ac.be (Postfix) with ESMTPSA id 1FA39200EECA; Fri, 25 Oct 2024 15:37:50 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 serv108.segi.ulg.ac.be 1FA39200EECA DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uliege.be; s=ulg20190529; t=1729863470; bh=M2cIWafnBBKhhrEbmEIY+ACXf3R2haiNwub60/8/wiU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=R9VWmsMkgk4eo20BmI3r6eqsulFVIry7dOitICEQl9ktxHjEhN3iHURcsi39tHfDG sF1nqSwkiuedl05UlCecS5FbQabXFLawDARpTXgercAtx8CN/zHXYs0bI/yi0zsIli JK1U2J753RuyMRBZVrRi53C8iArlvZ48fJOCjNxnZ9KE+NC5VdK4ZE1nU9OkT5oO9O M6lJKkAWvxRhGyTzQImEZN12n5Hv7RwC7izFP7QAmgzPTUwYLcuZfxrDfbj52FqZDg KWFKX72O+URj+vc1nw7zRatpxRpWUG3bOnYqTGBoEYeZA3lJeeYnYVCWkFmHR9n9tC GHSaHrQuYfaLQ== From: Justin Iurman To: netdev@vger.kernel.org Cc: davem@davemloft.net, dsahern@kernel.org, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, linux-kernel@vger.kernel.org, justin.iurman@uliege.be Subject: [PATCH net-next 3/3] net: ipv6: rpl_iptunnel: mitigate 2-realloc issue Date: Fri, 25 Oct 2024 15:37:27 +0200 Message-Id: <20241025133727.27742-4-justin.iurman@uliege.be> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20241025133727.27742-1-justin.iurman@uliege.be> References: <20241025133727.27742-1-justin.iurman@uliege.be> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This patch mitigates the two-reallocations issue with rpl_iptunnel by providing the dst_entry (in the cache) to the first call to skb_cow_head(). As a result, the very first iteration would still trigger two reallocations (i.e., empty cache), while next iterations would only trigger a single reallocation. Performance tests before/after applying this patch, which clearly shows there is no impact (it even shows improvement): - before: https://ibb.co/nQJhqwc - after: https://ibb.co/4ZvW6wV Signed-off-by: Justin Iurman --- net/ipv6/rpl_iptunnel.c | 60 +++++++++++++++++++++-------------------- 1 file changed, 31 insertions(+), 29 deletions(-) diff --git a/net/ipv6/rpl_iptunnel.c b/net/ipv6/rpl_iptunnel.c index db3c19a42e1c..ce722d9ec711 100644 --- a/net/ipv6/rpl_iptunnel.c +++ b/net/ipv6/rpl_iptunnel.c @@ -125,7 +125,8 @@ static void rpl_destroy_state(struct lwtunnel_state *lw= t) } =20 static int rpl_do_srh_inline(struct sk_buff *skb, const struct rpl_lwt *rl= wt, - const struct ipv6_rpl_sr_hdr *srh) + const struct ipv6_rpl_sr_hdr *srh, + struct dst_entry *dst) { struct ipv6_rpl_sr_hdr *isrh, *csrh; const struct ipv6hdr *oldhdr; @@ -153,7 +154,8 @@ static int rpl_do_srh_inline(struct sk_buff *skb, const= struct rpl_lwt *rlwt, =20 hdrlen =3D ((csrh->hdrlen + 1) << 3); =20 - err =3D skb_cow_head(skb, hdrlen + skb->mac_len); + err =3D skb_cow_head(skb, hdrlen + (!dst ? skb->mac_len + : LL_RESERVED_SPACE(dst->dev))); if (unlikely(err)) { kfree(buf); return err; @@ -186,36 +188,35 @@ static int rpl_do_srh_inline(struct sk_buff *skb, con= st struct rpl_lwt *rlwt, return 0; } =20 -static int rpl_do_srh(struct sk_buff *skb, const struct rpl_lwt *rlwt) +static int rpl_do_srh(struct sk_buff *skb, const struct rpl_lwt *rlwt, + struct dst_entry *dst) { - struct dst_entry *dst =3D skb_dst(skb); struct rpl_iptunnel_encap *tinfo; =20 if (skb->protocol !=3D htons(ETH_P_IPV6)) return -EINVAL; =20 - tinfo =3D rpl_encap_lwtunnel(dst->lwtstate); + tinfo =3D rpl_encap_lwtunnel(skb_dst(skb)->lwtstate); =20 - return rpl_do_srh_inline(skb, rlwt, tinfo->srh); + return rpl_do_srh_inline(skb, rlwt, tinfo->srh, dst); } =20 static int rpl_output(struct net *net, struct sock *sk, struct sk_buff *sk= b) { - struct dst_entry *orig_dst =3D skb_dst(skb); - struct dst_entry *dst =3D NULL; + struct dst_entry *dst; struct rpl_lwt *rlwt; int err; =20 - rlwt =3D rpl_lwt_lwtunnel(orig_dst->lwtstate); - - err =3D rpl_do_srh(skb, rlwt); - if (unlikely(err)) - goto drop; + rlwt =3D rpl_lwt_lwtunnel(skb_dst(skb)->lwtstate); =20 local_bh_disable(); dst =3D dst_cache_get(&rlwt->cache); local_bh_enable(); =20 + err =3D rpl_do_srh(skb, rlwt, dst); + if (unlikely(err)) + goto drop; + if (unlikely(!dst)) { struct ipv6hdr *hdr =3D ipv6_hdr(skb); struct flowi6 fl6; @@ -237,15 +238,15 @@ static int rpl_output(struct net *net, struct sock *s= k, struct sk_buff *skb) local_bh_disable(); dst_cache_set_ip6(&rlwt->cache, dst, &fl6.saddr); local_bh_enable(); + + err =3D skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); + if (unlikely(err)) + goto drop; } =20 skb_dst_drop(skb); skb_dst_set(skb, dst); =20 - err =3D skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); - if (unlikely(err)) - goto drop; - return dst_output(net, sk, skb); =20 drop: @@ -255,36 +256,37 @@ static int rpl_output(struct net *net, struct sock *s= k, struct sk_buff *skb) =20 static int rpl_input(struct sk_buff *skb) { - struct dst_entry *orig_dst =3D skb_dst(skb); - struct dst_entry *dst =3D NULL; + struct dst_entry *dst; struct rpl_lwt *rlwt; int err; =20 - rlwt =3D rpl_lwt_lwtunnel(orig_dst->lwtstate); - - err =3D rpl_do_srh(skb, rlwt); - if (unlikely(err)) - goto drop; + rlwt =3D rpl_lwt_lwtunnel(skb_dst(skb)->lwtstate); =20 local_bh_disable(); dst =3D dst_cache_get(&rlwt->cache); + local_bh_enable(); + + err =3D rpl_do_srh(skb, rlwt, dst); + if (unlikely(err)) + goto drop; =20 if (!dst) { ip6_route_input(skb); dst =3D skb_dst(skb); if (!dst->error) { + local_bh_disable(); dst_cache_set_ip6(&rlwt->cache, dst, &ipv6_hdr(skb)->saddr); + local_bh_enable(); } + + err =3D skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); + if (unlikely(err)) + goto drop; } else { skb_dst_drop(skb); skb_dst_set(skb, dst); } - local_bh_enable(); - - err =3D skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); - if (unlikely(err)) - goto drop; =20 return dst_input(skb); =20 --=20 2.34.1