Re: [PATCH v3] udp reuseport: fix packet of same flow hashed to different socket
From: Eric Dumazet <hidden>
Date: 2016-06-12 15:32:58
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On Sun, 2016-06-12 at 20:43 +0800, Su Xuemin wrote:
From: "Su, Xuemin" <redacted>
...
Signed-off-by: Su, Xuemin <redacted> Signed-off-by: Eric Dumazet <edumazet@google.com> ---
First, I want to thank you for this very high quality submission, especially if this is your first linux kernel patch. I have one additional comment to make :
quoted hunk ↗ jump to hunk
if (score > badness) { reuseport = sk->sk_reuseport;@@ -556,14 +510,20 @@ struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr, daddr, hnum, dif, hslot2, slot2, skb); if (!result) { + unsigned int old = hash2; hash2 = udp4_portaddr_hash(net, htonl(INADDR_ANY), hnum); + + /* avoid search the same slot again. */ + if (unlikely(old == hash2)) + return result; +
Technically speaking, what matters is the slot, not the hash value (32bit) So I would save in old, slot2
slot2 = hash2 & udptable->mask;
And here perform the check if (unlikely(slot2 != old_slot)) return result;
hslot2 = &udptable->hash2[slot2]; if (hslot->count < hslot2->count) goto begin;
(Same remark applies in IPv6) Thanks !