From nobody Mon Nov 25 09:42:01 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 DB8431DE3D2; Mon, 28 Oct 2024 22:36:25 +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=1730154988; cv=none; b=Y8C0JZMco9yIAqGkWfTsykhfQy7yX9fVEC7pD9ZFNkaGmAfV+BZLQFLfyicQWgh32RGDtIwzKsv0p/mj0GXFMHQHUXgSPgoNOpFGuhSDl+W114P1yQMGksxNE2xQvvYTD9wlcoU8k430FAhgrfbI/oc6gx7rDBmC7s7DP5m4/E4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730154988; c=relaxed/simple; bh=ilClyPQtRxrsdEANoquGAOae7YeLsPgwb/N5C57thMc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=LPmfxF8NQ8q4ZUd9cI7Pd5/RPrieL6/PJ6YZxKj5H1WXDN+nFJ5H2lDOR9pniRHtloqfyNETy5qTkNbSbQCj2aVkSGftvsi/EJuZUsRHze9ZpZDqKGDg0VV571ZM3NrSukmd6PlkWkCb6QoocYYHxUQm9bK5ZCEGG91vj2aVYQE= 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=EVYP8Xha; 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="EVYP8Xha" Received: from localhost.localdomain (unknown [10.29.254.136]) (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 131D9200DF94; Mon, 28 Oct 2024 23:36:22 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 serv108.segi.ulg.ac.be 131D9200DF94 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uliege.be; s=ulg20190529; t=1730154984; bh=HsRx5WoasynQ2MWTPxAcC1uxVEajhdd82qZcgSPFNK0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EVYP8XhaXta4w+0xqEJHDKhDx7qSBJZkpH6Q0t2cBJOhp1cVOuCPm/fMXGOqjIgzw aiHxkwDZZUn8s4YnvIldwop/8nzqxUbXsPf7xZVXOiY9/HBOguMA8oSx+CVDaIQ6SX 75WcR12G+N4FnZDjenbvxCVrDj0RdPIm5GMQKe44sdCxCiFo2FNiEmkz2ldJnLeV4e fWCNSAomFlK7q1BjUeAHIqbS/cqkYswJywpJQW+PXnAec78u+X4PdYGUSLI1ocOc3l TR759yujTLXoXOPIoPDWKCDG6YcXPARzAXUHTG0HCsPtnXYcBb1G1XXKze+P/obL7P ja3NpO9S59jug== 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 v3 1/3] net: ipv6: ioam6_iptunnel: mitigate 2-realloc issue Date: Mon, 28 Oct 2024 23:36:09 +0100 Message-Id: <20241028223611.26599-2-justin.iurman@uliege.be> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20241028223611.26599-1-justin.iurman@uliege.be> References: <20241028223611.26599-1-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 | 90 +++++++++++++++++++++------------------ 1 file changed, 49 insertions(+), 41 deletions(-) diff --git a/net/ipv6/ioam6_iptunnel.c b/net/ipv6/ioam6_iptunnel.c index beb6b4cfc551..07bfd557e08a 100644 --- a/net/ipv6/ioam6_iptunnel.c +++ b/net/ipv6/ioam6_iptunnel.c @@ -254,15 +254,24 @@ static int ioam6_do_fill(struct net *net, struct sk_b= uff *skb) return 0; } =20 +static inline int dev_overhead(struct dst_entry *dst, struct sk_buff *skb) +{ + if (likely(dst)) + return LL_RESERVED_SPACE(dst->dev); + + return skb->mac_len; +} + 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 + dev_overhead(dst, skb)); if (unlikely(err)) return err; =20 @@ -293,16 +302,16 @@ 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 + dev_overhead(dst, skb)); if (unlikely(err)) return err; =20 @@ -326,7 +335,7 @@ 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 +345,7 @@ 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 +354,7 @@ 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 +363,10 @@ 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 +374,7 @@ 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 +384,7 @@ 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 +402,40 @@ 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