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author | Martin KaFai Lau <kafai@fb.com> | 2022-03-02 20:55:25 +0100 |
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committer | David S. Miller <davem@davemloft.net> | 2022-03-03 15:38:48 +0100 |
commit | a1ac9c8acec1605c6b43af418f79facafdced680 (patch) | |
tree | cf89b2e7b2f5f92400c51eee74558c64674d5207 /net/bridge | |
parent | Merge branch 'dsa-unicast-filtering' (diff) | |
download | linux-a1ac9c8acec1605c6b43af418f79facafdced680.tar.xz linux-a1ac9c8acec1605c6b43af418f79facafdced680.zip |
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/bridge')
-rw-r--r-- | net/bridge/netfilter/nf_conntrack_bridge.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/bridge/netfilter/nf_conntrack_bridge.c b/net/bridge/netfilter/nf_conntrack_bridge.c index fdbed3158555..ebfb2a5c59e4 100644 --- a/net/bridge/netfilter/nf_conntrack_bridge.c +++ b/net/bridge/netfilter/nf_conntrack_bridge.c @@ -32,6 +32,7 @@ static int nf_br_ip_fragment(struct net *net, struct sock *sk, struct sk_buff *)) { int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size; + bool mono_delivery_time = skb->mono_delivery_time; unsigned int hlen, ll_rs, mtu; ktime_t tstamp = skb->tstamp; struct ip_frag_state state; @@ -81,7 +82,7 @@ static int nf_br_ip_fragment(struct net *net, struct sock *sk, if (iter.frag) ip_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; @@ -112,7 +113,7 @@ 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; |