6.6-stable review patch. If anyone has any objections, please let me know.
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From: Justin Iurman justin.iurman@uliege.be
[ Upstream commit 40475b63761abb6f8fdef960d03228a08662c9c4 ]
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@uliege.be Cc: David Lebrun dlebrun@google.com Signed-off-by: Paolo Abeni pabeni@redhat.com Stable-dep-of: c64a0727f9b1 ("net: ipv6: fix dst ref loop on input in seg6 lwt") Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/seg6_iptunnel.c | 85 ++++++++++++++++++++++++---------------- 1 file changed, 52 insertions(+), 33 deletions(-)
diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c index 098632adc9b5a..4bf937bfc2633 100644 --- a/net/ipv6/seg6_iptunnel.c +++ b/net/ipv6/seg6_iptunnel.c @@ -124,8 +124,8 @@ static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb, return flowlabel; }
-/* 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) +static int __seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, + int proto, struct dst_entry *cache_dst) { struct dst_entry *dst = skb_dst(skb); struct net *net = dev_net(dst->dev); @@ -137,7 +137,7 @@ 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 + dst_dev_overhead(cache_dst, skb)); if (unlikely(err)) return err;
@@ -197,11 +197,18 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
return 0; } + +/* 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) +{ + return __seg6_do_srh_encap(skb, osrh, proto, NULL); +} 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 *cache_dst) { __u8 first_seg = osrh->first_segment; struct dst_entry *dst = skb_dst(skb); @@ -230,7 +237,7 @@ 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 + dst_dev_overhead(cache_dst, skb)); if (unlikely(err)) return err;
@@ -317,8 +324,8 @@ static int seg6_do_srh_encap_red(struct sk_buff *skb, return 0; }
-/* 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) +static int __seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, + struct dst_entry *cache_dst) { struct ipv6hdr *hdr, *oldhdr; struct ipv6_sr_hdr *isrh; @@ -326,7 +333,7 @@ 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 + dst_dev_overhead(cache_dst, skb)); if (unlikely(err)) return err;
@@ -369,9 +376,8 @@ 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 *cache_dst) { struct dst_entry *dst = skb_dst(skb); struct seg6_iptunnel_encap *tinfo; @@ -384,7 +390,7 @@ static int seg6_do_srh(struct sk_buff *skb) 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, cache_dst); if (err) return err; break; @@ -402,9 +408,11 @@ 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, cache_dst); else - err = seg6_do_srh_encap_red(skb, tinfo->srh, proto); + err = seg6_do_srh_encap_red(skb, tinfo->srh, + proto, cache_dst);
if (err) return err; @@ -425,11 +433,13 @@ 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, + cache_dst); else err = seg6_do_srh_encap_red(skb, tinfo->srh, - IPPROTO_ETHERNET); + IPPROTO_ETHERNET, + cache_dst);
if (err) return err; @@ -444,6 +454,13 @@ static int seg6_do_srh(struct sk_buff *skb) return 0; }
+/* 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_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb) { @@ -458,31 +475,33 @@ static int seg6_input_core(struct net *net, struct sock *sk, struct seg6_lwt *slwt; int err;
- err = seg6_do_srh(skb); - if (unlikely(err)) - goto drop; - slwt = seg6_lwt_lwtunnel(orig_dst->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, @@ -528,16 +547,16 @@ static int seg6_output_core(struct net *net, struct sock *sk, struct seg6_lwt *slwt; int err;
- err = seg6_do_srh(skb); - if (unlikely(err)) - goto drop; - slwt = seg6_lwt_lwtunnel(orig_dst->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 +578,15 @@ 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);