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authorMartin KaFai Lau <kafai@fb.com>2022-03-02 22:55:25 +0300
committerDavid S. Miller <davem@davemloft.net>2022-03-03 17:38:48 +0300
commita1ac9c8acec1605c6b43af418f79facafdced680 (patch)
treecf89b2e7b2f5f92400c51eee74558c64674d5207 /net/ipv6
parent6fb8661c8f97bb062d2ecc7a57591d38e6c4f8c8 (diff)
downloadlinux-a1ac9c8acec1605c6b43af418f79facafdced680.tar.xz
net: Add skb->mono_delivery_time to distinguish mono delivery_time from (rcv) timestamp
skb->tstamp was first used as the (rcv) timestamp. The major usage is to report it to the user (e.g. SO_TIMESTAMP). Later, skb->tstamp is also set as the (future) delivery_time (e.g. EDT in TCP) during egress and used by the qdisc (e.g. sch_fq) to make decision on when the skb can be passed to the dev. Currently, there is no way to tell skb->tstamp having the (rcv) timestamp or the delivery_time, so it is always reset to 0 whenever forwarded between egress and ingress. While it makes sense to always clear the (rcv) timestamp in skb->tstamp to avoid confusing sch_fq that expects the delivery_time, it is a performance issue [0] to clear the delivery_time if the skb finally egress to a fq@phy-dev. For example, when forwarding from egress to ingress and then finally back to egress: tcp-sender => veth@netns => veth@hostns => fq@eth0@hostns ^ ^ reset rest This patch adds one bit skb->mono_delivery_time to flag the skb->tstamp is storing the mono delivery_time (EDT) instead of the (rcv) timestamp. The current use case is to keep the TCP mono delivery_time (EDT) and to be used with sch_fq. A latter patch will also allow tc-bpf@ingress to read and change the mono delivery_time. In the future, another bit (e.g. skb->user_delivery_time) can be added for the SCM_TXTIME where the clock base is tracked by sk->sk_clockid. [ This patch is a prep work. The following patches will get the other parts of the stack ready first. Then another patch after that will finally set the skb->mono_delivery_time. ] skb_set_delivery_time() function is added. It is used by the tcp_output.c and during ip[6] fragmentation to assign the delivery_time to the skb->tstamp and also set the skb->mono_delivery_time. A note on the change in ip_send_unicast_reply() in ip_output.c. It is only used by TCP to send reset/ack out of a ctl_sk. Like the new skb_set_delivery_time(), this patch sets the skb->mono_delivery_time to 0 for now as a place holder. It will be enabled in a latter patch. A similar case in tcp_ipv6 can be done with skb_set_delivery_time() in tcp_v6_send_response(). [0] (slide 22): https://linuxplumbersconf.org/event/11/contributions/953/attachments/867/1658/LPC_2021_BPF_Datapath_Extensions.pdf Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/ip6_output.c5
-rw-r--r--net/ipv6/netfilter.c5
-rw-r--r--net/ipv6/tcp_ipv6.c2
3 files changed, 7 insertions, 5 deletions
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index c5edc86b18bd..dad4e3d0492e 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -813,6 +813,7 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ?
inet6_sk(skb->sk) : NULL;
+ bool mono_delivery_time = skb->mono_delivery_time;
struct ip6_frag_state state;
unsigned int mtu, hlen, nexthdr_offset;
ktime_t tstamp = skb->tstamp;
@@ -903,7 +904,7 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
if (iter.frag)
ip6_fraglist_prepare(skb, &iter);
- skb->tstamp = tstamp;
+ skb_set_delivery_time(skb, tstamp, mono_delivery_time);
err = output(net, sk, skb);
if (!err)
IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
@@ -962,7 +963,7 @@ slow_path:
/*
* Put this fragment into the sending queue.
*/
- frag->tstamp = tstamp;
+ skb_set_delivery_time(frag, tstamp, mono_delivery_time);
err = output(net, sk, frag);
if (err)
goto fail;
diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
index 6ab710b5a1a8..1da332450d98 100644
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c
@@ -121,6 +121,7 @@ int br_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
struct sk_buff *))
{
int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
+ bool mono_delivery_time = skb->mono_delivery_time;
ktime_t tstamp = skb->tstamp;
struct ip6_frag_state state;
u8 *prevhdr, nexthdr = 0;
@@ -186,7 +187,7 @@ int br_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
if (iter.frag)
ip6_fraglist_prepare(skb, &iter);
- skb->tstamp = tstamp;
+ skb_set_delivery_time(skb, tstamp, mono_delivery_time);
err = output(net, sk, data, skb);
if (err || !iter.frag)
break;
@@ -219,7 +220,7 @@ slow_path:
goto blackhole;
}
- skb2->tstamp = tstamp;
+ skb_set_delivery_time(skb2, tstamp, mono_delivery_time);
err = output(net, sk, data, skb2);
if (err)
goto blackhole;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index e98af869ff3a..cb2bb7d2e907 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -940,7 +940,7 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
} else {
mark = sk->sk_mark;
}
- buff->tstamp = tcp_transmit_time(sk);
+ skb_set_delivery_time(buff, tcp_transmit_time(sk), true);
}
fl6.flowi6_mark = IP6_REPLY_MARK(net, skb->mark) ?: mark;
fl6.fl6_dport = t1->dest;