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Message-Id: <20241028220212.24132-3-justin.iurman@uliege.be>
Date: Mon, 28 Oct 2024 23:02:11 +0100
From: Justin Iurman <justin.iurman@...ege.be>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
dsahern@...nel.org,
edumazet@...gle.com,
kuba@...nel.org,
pabeni@...hat.com,
horms@...nel.org,
linux-kernel@...r.kernel.org,
justin.iurman@...ege.be,
David Lebrun <dlebrun@...gle.com>
Subject: [PATCH net-next v2 2/3] net: ipv6: seg6_iptunnel: mitigate 2-realloc issue
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 <justin.iurman@...ege.be>
Cc: David Lebrun <dlebrun@...gle.com>
---
net/ipv6/seg6_iptunnel.c | 108 +++++++++++++++++++++++----------------
1 file changed, 63 insertions(+), 45 deletions(-)
diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c
index 098632adc9b5..a915b6c94c72 100644
--- a/net/ipv6/seg6_iptunnel.c
+++ b/net/ipv6/seg6_iptunnel.c
@@ -124,11 +124,25 @@ static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb,
return flowlabel;
}
+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;
+}
+
/* 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 proto)
{
- struct dst_entry *dst = skb_dst(skb);
- struct net *net = dev_net(dst->dev);
+ return __seg6_do_srh_encap(skb, osrh, proto, NULL);
+}
+EXPORT_SYMBOL_GPL(seg6_do_srh_encap);
+
+static int __seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh,
+ int proto, struct dst_entry *dst)
+{
+ struct net *net = dev_net(skb_dst(skb)->dev);
struct ipv6hdr *hdr, *inner_hdr;
struct ipv6_sr_hdr *isrh;
int hdrlen, tot_len, err;
@@ -137,7 +151,7 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
hdrlen = (osrh->hdrlen + 1) << 3;
tot_len = hdrlen + sizeof(*hdr);
- err = skb_cow_head(skb, tot_len + skb->mac_len);
+ err = skb_cow_head(skb, tot_len + dev_overhead(dst, skb));
if (unlikely(err))
return err;
@@ -181,7 +195,7 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
isrh->nexthdr = proto;
hdr->daddr = 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);
#ifdef CONFIG_IPV6_SEG6_HMAC
if (sr_has_hmac(isrh)) {
@@ -197,15 +211,14 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
return 0;
}
-EXPORT_SYMBOL_GPL(seg6_do_srh_encap);
/* 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 = osrh->first_segment;
- struct dst_entry *dst = skb_dst(skb);
- struct net *net = dev_net(dst->dev);
+ struct net *net = dev_net(skb_dst(skb)->dev);
struct ipv6hdr *hdr, *inner_hdr;
int hdrlen = ipv6_optlen(osrh);
int red_tlv_offset, tlv_offset;
@@ -230,7 +243,7 @@ static int seg6_do_srh_encap_red(struct sk_buff *skb,
tot_len = red_hdrlen + sizeof(struct ipv6hdr);
- err = skb_cow_head(skb, tot_len + skb->mac_len);
+ err = skb_cow_head(skb, tot_len + dev_overhead(dst, skb));
if (unlikely(err))
return err;
@@ -263,7 +276,7 @@ static int seg6_do_srh_encap_red(struct sk_buff *skb,
if (skip_srh) {
hdr->nexthdr = proto;
- set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
+ set_tun_src(net, skb_dst(skb)->dev, &hdr->daddr, &hdr->saddr);
goto out;
}
@@ -299,7 +312,7 @@ static int seg6_do_srh_encap_red(struct sk_buff *skb,
srcaddr:
isrh->nexthdr = proto;
- set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
+ set_tun_src(net, skb_dst(skb)->dev, &hdr->daddr, &hdr->saddr);
#ifdef CONFIG_IPV6_SEG6_HMAC
if (unlikely(!skip_srh && sr_has_hmac(isrh))) {
@@ -319,6 +332,13 @@ static int seg6_do_srh_encap_red(struct sk_buff *skb,
/* 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);
+
+static 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 +346,7 @@ int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
hdrlen = (osrh->hdrlen + 1) << 3;
- err = skb_cow_head(skb, hdrlen + skb->mac_len);
+ err = skb_cow_head(skb, hdrlen + dev_overhead(dst, skb));
if (unlikely(err))
return err;
@@ -369,22 +389,20 @@ int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
return 0;
}
-EXPORT_SYMBOL_GPL(seg6_do_srh_inline);
-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 = skb_dst(skb);
struct seg6_iptunnel_encap *tinfo;
int proto, err = 0;
- tinfo = seg6_encap_lwtunnel(dst->lwtstate);
+ tinfo = seg6_encap_lwtunnel(skb_dst(skb)->lwtstate);
switch (tinfo->mode) {
case SEG6_IPTUN_MODE_INLINE:
if (skb->protocol != htons(ETH_P_IPV6))
return -EINVAL;
- err = seg6_do_srh_inline(skb, tinfo->srh);
+ err = __seg6_do_srh_inline(skb, tinfo->srh, dst);
if (err)
return err;
break;
@@ -402,9 +420,9 @@ static int seg6_do_srh(struct sk_buff *skb)
return -EINVAL;
if (tinfo->mode == SEG6_IPTUN_MODE_ENCAP)
- err = seg6_do_srh_encap(skb, tinfo->srh, proto);
+ err = __seg6_do_srh_encap(skb, tinfo->srh, proto, dst);
else
- err = seg6_do_srh_encap_red(skb, tinfo->srh, proto);
+ err = seg6_do_srh_encap_red(skb, tinfo->srh, proto, dst);
if (err)
return err;
@@ -425,11 +443,11 @@ static int seg6_do_srh(struct sk_buff *skb)
skb_push(skb, skb->mac_len);
if (tinfo->mode == SEG6_IPTUN_MODE_L2ENCAP)
- err = seg6_do_srh_encap(skb, tinfo->srh,
- IPPROTO_ETHERNET);
+ err = __seg6_do_srh_encap(skb, tinfo->srh,
+ IPPROTO_ETHERNET, dst);
else
err = seg6_do_srh_encap_red(skb, tinfo->srh,
- IPPROTO_ETHERNET);
+ IPPROTO_ETHERNET, dst);
if (err)
return err;
@@ -453,36 +471,37 @@ 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 = skb_dst(skb);
- struct dst_entry *dst = NULL;
+ struct dst_entry *dst;
struct seg6_lwt *slwt;
int err;
- err = seg6_do_srh(skb);
- if (unlikely(err))
- goto drop;
-
- slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
+ slwt = seg6_lwt_lwtunnel(skb_dst(skb)->lwtstate);
local_bh_disable();
dst = dst_cache_get(&slwt->cache);
+ local_bh_enable();
+
+ err = seg6_do_srh(skb, dst);
+ if (unlikely(err))
+ goto drop;
if (!dst) {
ip6_route_input(skb);
dst = skb_dst(skb);
if (!dst->error) {
+ local_bh_disable();
dst_cache_set_ip6(&slwt->cache, dst,
&ipv6_hdr(skb)->saddr);
+ local_bh_enable();
}
+
+ err = 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 = 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,
@@ -523,21 +542,20 @@ 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 = skb_dst(skb);
- struct dst_entry *dst = NULL;
+ struct dst_entry *dst;
struct seg6_lwt *slwt;
int err;
- err = seg6_do_srh(skb);
- if (unlikely(err))
- goto drop;
-
- slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
+ slwt = seg6_lwt_lwtunnel(skb_dst(skb)->lwtstate);
local_bh_disable();
dst = dst_cache_get(&slwt->cache);
local_bh_enable();
+ err = seg6_do_srh(skb, dst);
+ if (unlikely(err))
+ goto drop;
+
if (unlikely(!dst)) {
struct ipv6hdr *hdr = ipv6_hdr(skb);
struct flowi6 fl6;
@@ -559,15 +577,15 @@ static int seg6_output_core(struct net *net, struct sock *sk,
local_bh_disable();
dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr);
local_bh_enable();
+
+ err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
+ if (unlikely(err))
+ goto drop;
}
skb_dst_drop(skb);
skb_dst_set(skb, dst);
- err = 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);
--
2.34.1
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