From patchwork Tue Dec 3 12:49:43 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Justin Iurman X-Patchwork-Id: 13892377 X-Patchwork-Delegate: kuba@kernel.org 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 870C01E53A; Tue, 3 Dec 2024 12:59:52 +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=1733230794; cv=none; b=cfgkUVj7Z0s31gV8gREhr1rU41PJYDoMkS4Q2CuGwkQSzbKfwMrs/716StNmrZQMzUFO46zNrm7OnR94XJFuoA3Qo1WfQxmdO1zQn2Tkth0VmC0nQYslrfT0WZwU+9AqHa/2uHCo4gq4zV7JflxIJuQYzZBZlquxo/gzbEqiGoY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733230794; c=relaxed/simple; bh=NxyQcAFC+EIcEx4ym0rUYYFqK38LZuoe4X6+NBqzFI8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Cz40q7j+IUSdtwDyhAoT0mjaO6NZ3wGx1ctUPgYuCuYHf72ESzazlA4YwLMwujnGwJiVW3u1f8SkXBbmhBPxWJE6OFAVaWKqsf0Tsa0BrpGSpcn6L+qBCauV2tE0VYn1tPIWq2vdJtsZzH8wAkNruIT/qzdPIWMwWOaYx+lrIp4= 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=C8rxz9ti; 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="C8rxz9ti" Received: from ubuntu.home (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 66573200E1FD; Tue, 3 Dec 2024 13:49:54 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 serv108.segi.ulg.ac.be 66573200E1FD DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uliege.be; s=ulg20190529; t=1733230194; bh=mQveZItNLzTIo34Os3uLO1zS26WneyxGStddfBwzByY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=C8rxz9tifz7t2Kfe0pHs6PzAEWQcj9sBUMn9hS5/R8izQBdPsmoCV7ObTGyZFHeZ6 UlY1lz7kuF4wsIPb029ai8NyJt/Hyy72k4LFgtqWR/sCPLxMVv4mVmccuBJTJwFahU raVyLBcaoogGvfU0YreNm2FJodoMw6RKGtQD4I6y8RStBxVPL62BJLPFGexcahFRdq 3OIzBzOARPDsBGN5rDspPb72RYkF2rFaZrK9WEHbUo41ke6Tvo2aeAzKWxblUSr+LQ 8jED026kdws+VTPJZ7brl8PPx+joIx4Q9Ivu2485cea7srv69Imr1DS+XfAkf9HPkv W8zWFNgPJr8dQ== 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: [RESEND PATCH net-next v5 2/4] net: ipv6: ioam6_iptunnel: mitigate 2-realloc issue Date: Tue, 3 Dec 2024 13:49:43 +0100 Message-Id: <20241203124945.22508-3-justin.iurman@uliege.be> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20241203124945.22508-1-justin.iurman@uliege.be> References: <20241203124945.22508-1-justin.iurman@uliege.be> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org 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 may 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 | 73 ++++++++++++++++++++------------------- 1 file changed, 37 insertions(+), 36 deletions(-) diff --git a/net/ipv6/ioam6_iptunnel.c b/net/ipv6/ioam6_iptunnel.c index 9d8422e350f8..28e5a89dc255 100644 --- a/net/ipv6/ioam6_iptunnel.c +++ b/net/ipv6/ioam6_iptunnel.c @@ -253,14 +253,15 @@ static int ioam6_do_fill(struct net *net, struct sk_buff *skb) } 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 *cache_dst) { struct ipv6hdr *oldhdr, *hdr; int hdrlen, err; hdrlen = (tuninfo->eh.hdrlen + 1) << 3; - err = skb_cow_head(skb, hdrlen + skb->mac_len); + err = skb_cow_head(skb, hdrlen + dst_dev_overhead(cache_dst, skb)); if (unlikely(err)) return err; @@ -291,7 +292,8 @@ 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 *cache_dst) { struct dst_entry *dst = skb_dst(skb); struct ipv6hdr *hdr, *inner_hdr; @@ -300,7 +302,7 @@ static int ioam6_do_encap(struct net *net, struct sk_buff *skb, hdrlen = (tuninfo->eh.hdrlen + 1) << 3; len = sizeof(*hdr) + hdrlen; - err = skb_cow_head(skb, len + skb->mac_len); + err = skb_cow_head(skb, len + dst_dev_overhead(cache_dst, skb)); if (unlikely(err)) return err; @@ -334,7 +336,7 @@ static int ioam6_do_encap(struct net *net, struct sk_buff *skb, static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb) { - struct dst_entry *dst = skb_dst(skb); + struct dst_entry *dst = skb_dst(skb), *cache_dst; struct in6_addr orig_daddr; struct ioam6_lwt *ilwt; int err = -EINVAL; @@ -352,6 +354,10 @@ static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb) orig_daddr = ipv6_hdr(skb)->daddr; + local_bh_disable(); + cache_dst = dst_cache_get(&ilwt->cache); + local_bh_enable(); + switch (ilwt->mode) { case IOAM6_IPTUNNEL_MODE_INLINE: do_inline: @@ -359,7 +365,7 @@ static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb) if (ipv6_hdr(skb)->nexthdr == NEXTHDR_HOP) goto out; - err = ioam6_do_inline(net, skb, &ilwt->tuninfo); + err = ioam6_do_inline(net, skb, &ilwt->tuninfo, cache_dst); if (unlikely(err)) goto drop; @@ -369,7 +375,7 @@ static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb) /* Encapsulation (ip6ip6) */ err = ioam6_do_encap(net, skb, &ilwt->tuninfo, ilwt->has_tunsrc, &ilwt->tunsrc, - &ilwt->tundst); + &ilwt->tundst, cache_dst); if (unlikely(err)) goto drop; @@ -387,41 +393,36 @@ static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb) goto drop; } - err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); - if (unlikely(err)) - goto drop; + if (unlikely(!cache_dst)) { + struct ipv6hdr *hdr = ipv6_hdr(skb); + struct flowi6 fl6; + + memset(&fl6, 0, sizeof(fl6)); + fl6.daddr = hdr->daddr; + fl6.saddr = hdr->saddr; + fl6.flowlabel = ip6_flowinfo(hdr); + fl6.flowi6_mark = skb->mark; + fl6.flowi6_proto = hdr->nexthdr; + + cache_dst = ip6_route_output(net, NULL, &fl6); + if (cache_dst->error) { + err = cache_dst->error; + dst_release(cache_dst); + goto drop; + } - if (!ipv6_addr_equal(&orig_daddr, &ipv6_hdr(skb)->daddr)) { local_bh_disable(); - dst = dst_cache_get(&ilwt->cache); + dst_cache_set_ip6(&ilwt->cache, cache_dst, &fl6.saddr); local_bh_enable(); - if (unlikely(!dst)) { - struct ipv6hdr *hdr = ipv6_hdr(skb); - struct flowi6 fl6; - - memset(&fl6, 0, sizeof(fl6)); - fl6.daddr = hdr->daddr; - fl6.saddr = hdr->saddr; - fl6.flowlabel = ip6_flowinfo(hdr); - fl6.flowi6_mark = skb->mark; - fl6.flowi6_proto = hdr->nexthdr; - - dst = ip6_route_output(net, NULL, &fl6); - if (dst->error) { - err = dst->error; - dst_release(dst); - goto drop; - } - - local_bh_disable(); - dst_cache_set_ip6(&ilwt->cache, dst, &fl6.saddr); - local_bh_enable(); - } + err = skb_cow_head(skb, LL_RESERVED_SPACE(cache_dst->dev)); + if (unlikely(err)) + goto drop; + } + if (!ipv6_addr_equal(&orig_daddr, &ipv6_hdr(skb)->daddr)) { skb_dst_drop(skb); - skb_dst_set(skb, dst); - + skb_dst_set(skb, cache_dst); return dst_output(net, sk, skb); } out: