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Message-Id: <20241028220212.24132-4-justin.iurman@uliege.be>
Date: Mon, 28 Oct 2024 23:02:12 +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,
Alexander Aring <aahringo@...hat.com>
Subject: [PATCH net-next v2 3/3] net: ipv6: rpl_iptunnel: mitigate 2-realloc issue
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 <justin.iurman@...ege.be>
Cc: Alexander Aring <aahringo@...hat.com>
---
net/ipv6/rpl_iptunnel.c | 67 +++++++++++++++++++++++------------------
1 file changed, 38 insertions(+), 29 deletions(-)
diff --git a/net/ipv6/rpl_iptunnel.c b/net/ipv6/rpl_iptunnel.c
index db3c19a42e1c..c518728460a2 100644
--- a/net/ipv6/rpl_iptunnel.c
+++ b/net/ipv6/rpl_iptunnel.c
@@ -124,8 +124,17 @@ static void rpl_destroy_state(struct lwtunnel_state *lwt)
dst_cache_destroy(&rpl_lwt_lwtunnel(lwt)->cache);
}
+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 rpl_do_srh_inline(struct sk_buff *skb, const struct rpl_lwt *rlwt,
- 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 +162,7 @@ static int rpl_do_srh_inline(struct sk_buff *skb, const struct rpl_lwt *rlwt,
hdrlen = ((csrh->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)) {
kfree(buf);
return err;
@@ -186,36 +195,35 @@ static int rpl_do_srh_inline(struct sk_buff *skb, const struct rpl_lwt *rlwt,
return 0;
}
-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 = skb_dst(skb);
struct rpl_iptunnel_encap *tinfo;
if (skb->protocol != htons(ETH_P_IPV6))
return -EINVAL;
- tinfo = rpl_encap_lwtunnel(dst->lwtstate);
+ tinfo = rpl_encap_lwtunnel(skb_dst(skb)->lwtstate);
- return rpl_do_srh_inline(skb, rlwt, tinfo->srh);
+ return rpl_do_srh_inline(skb, rlwt, tinfo->srh, dst);
}
static int rpl_output(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 rpl_lwt *rlwt;
int err;
- rlwt = rpl_lwt_lwtunnel(orig_dst->lwtstate);
-
- err = rpl_do_srh(skb, rlwt);
- if (unlikely(err))
- goto drop;
+ rlwt = rpl_lwt_lwtunnel(skb_dst(skb)->lwtstate);
local_bh_disable();
dst = dst_cache_get(&rlwt->cache);
local_bh_enable();
+ err = rpl_do_srh(skb, rlwt, dst);
+ if (unlikely(err))
+ goto drop;
+
if (unlikely(!dst)) {
struct ipv6hdr *hdr = ipv6_hdr(skb);
struct flowi6 fl6;
@@ -237,15 +245,15 @@ static int rpl_output(struct net *net, struct sock *sk, struct sk_buff *skb)
local_bh_disable();
dst_cache_set_ip6(&rlwt->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;
-
return dst_output(net, sk, skb);
drop:
@@ -255,36 +263,37 @@ static int rpl_output(struct net *net, struct sock *sk, struct sk_buff *skb)
static int rpl_input(struct sk_buff *skb)
{
- struct dst_entry *orig_dst = skb_dst(skb);
- struct dst_entry *dst = NULL;
+ struct dst_entry *dst;
struct rpl_lwt *rlwt;
int err;
- rlwt = rpl_lwt_lwtunnel(orig_dst->lwtstate);
-
- err = rpl_do_srh(skb, rlwt);
- if (unlikely(err))
- goto drop;
+ rlwt = rpl_lwt_lwtunnel(skb_dst(skb)->lwtstate);
local_bh_disable();
dst = dst_cache_get(&rlwt->cache);
+ local_bh_enable();
+
+ err = rpl_do_srh(skb, rlwt, 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(&rlwt->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;
return dst_input(skb);
--
2.34.1
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