This is a note to let you know that I've just added the patch titled
udp: re-score reuseport groups when connected sockets are present
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
udp-re-score-reuseport-groups-when-connected-sockets.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 9e8c14762c6cc4c7ef197009401c5774bc872e7f
Author: Lorenz Bauer <lmb@xxxxxxxxxxxxx>
Date: Thu Jul 20 17:30:05 2023 +0200
udp: re-score reuseport groups when connected sockets are present
[ Upstream commit f0ea27e7bfe1c34e1f451a63eb68faa1d4c3a86d ]
Contrary to TCP, UDP reuseport groups can contain TCP_ESTABLISHED
sockets. To support these properly we remember whether a group has
a connected socket and skip the fast reuseport early-return. In
effect we continue scoring all reuseport sockets and then choose the
one with the highest score.
The current code fails to re-calculate the score for the result of
lookup_reuseport. According to Kuniyuki Iwashima:
1) SO_INCOMING_CPU is set
-> selected sk might have +1 score
2) BPF prog returns ESTABLISHED and/or SO_INCOMING_CPU sk
-> selected sk will have more than 8
Using the old score could trigger more lookups depending on the
order that sockets are created.
sk -> sk (SO_INCOMING_CPU) -> sk (ESTABLISHED)
| |
`-> select the next SO_INCOMING_CPU sk
|
`-> select itself (We should save this lookup)
Fixes: efc6b6f6c311 ("udp: Improve load balancing for SO_REUSEPORT.")
Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Signed-off-by: Lorenz Bauer <lmb@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230720-so-reuseport-v6-1-7021b683cdae@xxxxxxxxxxxxx
Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index abfa860367aa9..b3aa68ea29de2 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -452,14 +452,24 @@ static struct sock *udp4_lib_lookup2(struct net *net,
score = compute_score(sk, net, saddr, sport,
daddr, hnum, dif, sdif);
if (score > badness) {
- result = lookup_reuseport(net, sk, skb,
- saddr, sport, daddr, hnum);
+ badness = score;
+ result = lookup_reuseport(net, sk, skb, saddr, sport, daddr, hnum);
+ if (!result) {
+ result = sk;
+ continue;
+ }
+
/* Fall back to scoring if group has connections */
- if (result && !reuseport_has_conns(sk))
+ if (!reuseport_has_conns(sk))
return result;
- result = result ? : sk;
- badness = score;
+ /* Reuseport logic returned an error, keep original score. */
+ if (IS_ERR(result))
+ continue;
+
+ badness = compute_score(result, net, saddr, sport,
+ daddr, hnum, dif, sdif);
+
}
}
return result;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 486d893b8e3ca..3ffca158d3e11 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -195,14 +195,23 @@ static struct sock *udp6_lib_lookup2(struct net *net,
score = compute_score(sk, net, saddr, sport,
daddr, hnum, dif, sdif);
if (score > badness) {
- result = lookup_reuseport(net, sk, skb,
- saddr, sport, daddr, hnum);
+ badness = score;
+ result = lookup_reuseport(net, sk, skb, saddr, sport, daddr, hnum);
+ if (!result) {
+ result = sk;
+ continue;
+ }
+
/* Fall back to scoring if group has connections */
- if (result && !reuseport_has_conns(sk))
+ if (!reuseport_has_conns(sk))
return result;
- result = result ? : sk;
- badness = score;
+ /* Reuseport logic returned an error, keep original score. */
+ if (IS_ERR(result))
+ continue;
+
+ badness = compute_score(sk, net, saddr, sport,
+ daddr, hnum, dif, sdif);
}
}
return result;
