[PATCH net-next 08/10] ipv6: refactor opts push in __ip6_make_skb()

[PATCH net-next 08/10] ipv6: refactor opts push in __ip6_make_skb()

[Pavel Begunkov]

Don't preload v6_cork->opt before we actually need it, it likely to be
saved on the stack and read again for no good reason.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 net/ipv6/ip6_output.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 976554d0fdec..43a541bbcf5f 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1855,7 +1855,6 @@ struct sk_buff *__ip6_make_skb(struct sock *sk,
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	struct net *net = sock_net(sk);
 	struct ipv6hdr *hdr;
-	struct ipv6_txoptions *opt = v6_cork->opt;
 	struct rt6_info *rt = (struct rt6_info *)cork->base.dst;
 	struct flowi6 *fl6 = &cork->fl.u.ip6;
 	unsigned char proto = fl6->flowi6_proto;
@@ -1884,10 +1883,14 @@ struct sk_buff *__ip6_make_skb(struct sock *sk,
 	__skb_pull(skb, skb_network_header_len(skb));
 
 	final_dst = &fl6->daddr;
-	if (opt && opt->opt_flen)
-		ipv6_push_frag_opts(skb, opt, &proto);
-	if (opt && opt->opt_nflen)
-		ipv6_push_nfrag_opts(skb, opt, &proto, &final_dst, &fl6->saddr);
+	if (v6_cork->opt) {
+		struct ipv6_txoptions *opt = v6_cork->opt;
+
+		if (opt->opt_flen)
+			ipv6_push_frag_opts(skb, opt, &proto);
+		if (opt->opt_nflen)
+			ipv6_push_nfrag_opts(skb, opt, &proto, &final_dst, &fl6->saddr);
+	}
 
 	skb_push(skb, sizeof(struct ipv6hdr));
 	skb_reset_network_header(skb);
-- 
2.36.0

Re: [PATCH net-next 08/10] ipv6: refactor opts push in __ip6_make_skb()

[Paolo Abeni]

On Thu, 2022-04-28 at 11:56 +0100, Pavel Begunkov wrote:
> Don't preload v6_cork->opt before we actually need it, it likely to be
> saved on the stack and read again for no good reason.
> 
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>

It looks like most part of this series has been lost ?!? only 8/10,
9/10 and 10/10 landed on the ML. Could you please double check?

Thanks

Paolo

Re: [PATCH net-next 08/10] ipv6: refactor opts push in __ip6_make_skb()

[Pavel Begunkov]

On 4/28/22 14:42, Paolo Abeni wrote:
> On Thu, 2022-04-28 at 11:56 +0100, Pavel Begunkov wrote:
>> Don't preload v6_cork->opt before we actually need it, it likely to be
>> saved on the stack and read again for no good reason.
>>
>> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> 
> It looks like most part of this series has been lost ?!? only 8/10,
> 9/10 and 10/10 landed on the ML. Could you please double check?

Seems I somehow sent duplicates of those and with weird numbering,
sorry for that. Let me resend the set, will tag v2 for convenience.

-- 
Pavel Begunkov

[PATCH net-next 09/10] ipv6: improve opt-less __ip6_make_skb()

[Pavel Begunkov]

We do a bit of a network header pointer shuffling in __ip6_make_skb()
expecting that ipv6_push_*frag_opts() might change the layout. Avoid it
with associated overhead when there are no opts.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 net/ipv6/ip6_output.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 43a541bbcf5f..416d14299242 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1880,22 +1880,20 @@ struct sk_buff *__ip6_make_skb(struct sock *sk,
 
 	/* Allow local fragmentation. */
 	skb->ignore_df = ip6_sk_ignore_df(sk);
-	__skb_pull(skb, skb_network_header_len(skb));
-
 	final_dst = &fl6->daddr;
 	if (v6_cork->opt) {
 		struct ipv6_txoptions *opt = v6_cork->opt;
 
+		__skb_pull(skb, skb_network_header_len(skb));
 		if (opt->opt_flen)
 			ipv6_push_frag_opts(skb, opt, &proto);
 		if (opt->opt_nflen)
 			ipv6_push_nfrag_opts(skb, opt, &proto, &final_dst, &fl6->saddr);
+		skb_push(skb, sizeof(struct ipv6hdr));
+		skb_reset_network_header(skb);
 	}
 
-	skb_push(skb, sizeof(struct ipv6hdr));
-	skb_reset_network_header(skb);
 	hdr = ipv6_hdr(skb);
-
 	ip6_flow_hdr(hdr, v6_cork->tclass,
 		     ip6_make_flowlabel(net, skb, fl6->flowlabel,
 					ip6_autoflowlabel(net, np), fl6));
-- 
2.36.0

[PATCH net-next 10/10] ipv6: clean up ip6_setup_cork

[Pavel Begunkov]

Do a bit of refactoring for ip6_setup_cork(). Cache a xfrm_dst_path()
result to not call it twice, reshuffle ifs to not repeat some parts
twice and so.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 net/ipv6/ip6_output.c | 30 +++++++++++++-----------------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 416d14299242..a17b26d5f34d 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1358,15 +1358,13 @@ static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork,
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	unsigned int mtu;
 	struct ipv6_txoptions *nopt, *opt = ipc6->opt;
+	struct dst_entry *xrfm_dst;
 
 	/* callers pass dst together with a reference, set it first so
 	 * ip6_cork_release() can put it down even in case of an error.
 	 */
 	cork->base.dst = &rt->dst;
 
-	/*
-	 * setup for corking
-	 */
 	if (opt) {
 		if (WARN_ON(v6_cork->opt))
 			return -EINVAL;
@@ -1399,28 +1397,26 @@ static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork,
 	}
 	v6_cork->hop_limit = ipc6->hlimit;
 	v6_cork->tclass = ipc6->tclass;
-	if (rt->dst.flags & DST_XFRM_TUNNEL)
-		mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
-		      READ_ONCE(rt->dst.dev->mtu) : dst_mtu(&rt->dst);
+
+	xrfm_dst = xfrm_dst_path(&rt->dst);
+	if (dst_allfrag(xrfm_dst))
+		cork->base.flags |= IPCORK_ALLFRAG;
+
+	if (np->pmtudisc < IPV6_PMTUDISC_PROBE)
+		mtu = dst_mtu(rt->dst.flags & DST_XFRM_TUNNEL ? &rt->dst : xrfm_dst);
 	else
-		mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
-			READ_ONCE(rt->dst.dev->mtu) : dst_mtu(xfrm_dst_path(&rt->dst));
-	if (np->frag_size < mtu) {
-		if (np->frag_size)
-			mtu = np->frag_size;
-	}
+		mtu = READ_ONCE(rt->dst.dev->mtu);
+
+	if (np->frag_size < mtu && np->frag_size)
+		mtu = np->frag_size;
+
 	cork->base.fragsize = mtu;
 	cork->base.gso_size = ipc6->gso_size;
 	cork->base.tx_flags = 0;
 	cork->base.mark = ipc6->sockc.mark;
 	sock_tx_timestamp(sk, ipc6->sockc.tsflags, &cork->base.tx_flags);
-
-	if (dst_allfrag(xfrm_dst_path(&rt->dst)))
-		cork->base.flags |= IPCORK_ALLFRAG;
 	cork->base.length = 0;
-
 	cork->base.transmit_time = ipc6->sockc.transmit_time;
-
 	return 0;
 }
 
-- 
2.36.0