Re: [PATCH net-next 3/9] netfilter: conntrack: avoid reload of ct->status
From: Roi Dayan <hidden>
Date: 2023-01-23 11:38:37
Also in:
netfilter-devel
On 18/01/2023 14:32, Florian Westphal wrote:
quoted hunk ↗ jump to hunk
Compiler can't merge the two test_bit() calls, so load ct->status once and use non-atomic accesses. This is fine because IPS_EXPECTED or NAT_CLASH are either set at ct creation time or not at all, but compiler can't know that. Signed-off-by: Florian Westphal <fw@strlen.de> --- net/netfilter/nf_conntrack_core.c | 9 +++++---- net/netfilter/nf_conntrack_proto_udp.c | 10 ++++++---- 2 files changed, 11 insertions(+), 8 deletions(-)diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 81ece117033a..9e12cade4e0f 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c@@ -1854,14 +1854,15 @@ resolve_normal_ct(struct nf_conn *tmpl, if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) { ctinfo = IP_CT_ESTABLISHED_REPLY; } else { + unsigned long status = READ_ONCE(ct->status); + /* Once we've had two way comms, always ESTABLISHED. */ - if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { + if (likely(status & IPS_SEEN_REPLY)) ctinfo = IP_CT_ESTABLISHED; - } else if (test_bit(IPS_EXPECTED_BIT, &ct->status)) { + else if (status & IPS_EXPECTED) ctinfo = IP_CT_RELATED; - } else { + else ctinfo = IP_CT_NEW; - } } nf_ct_set(skb, ct, ctinfo); return 0;diff --git a/net/netfilter/nf_conntrack_proto_udp.c b/net/netfilter/nf_conntrack_proto_udp.c index 3b516cffc779..6b9206635b24 100644 --- a/net/netfilter/nf_conntrack_proto_udp.c +++ b/net/netfilter/nf_conntrack_proto_udp.c@@ -88,6 +88,7 @@ int nf_conntrack_udp_packet(struct nf_conn *ct, const struct nf_hook_state *state) { unsigned int *timeouts; + unsigned long status; if (udp_error(skb, dataoff, state)) return -NF_ACCEPT;@@ -96,26 +97,27 @@ int nf_conntrack_udp_packet(struct nf_conn *ct, if (!timeouts) timeouts = udp_get_timeouts(nf_ct_net(ct)); - if (!nf_ct_is_confirmed(ct)) + status = READ_ONCE(ct->status); + if ((status & IPS_CONFIRMED) == 0) ct->proto.udp.stream_ts = 2 * HZ + jiffies; /* If we've seen traffic both ways, this is some kind of UDP * stream. Set Assured. */ - if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { + if (status & IPS_SEEN_REPLY_BIT) {
Hi, This change has a bug not matching reply status anymore. Since you don't use test_bit() you should use IPS_SEEN_REPLY instead of IPS_SEEN_REPLY_BIT. Thanks, Roi
unsigned long extra = timeouts[UDP_CT_UNREPLIED];
bool stream = false;
/* Still active after two seconds? Extend timeout. */
if (time_after(jiffies, ct->proto.udp.stream_ts)) {
extra = timeouts[UDP_CT_REPLIED];
- stream = true;
+ stream = (status & IPS_ASSURED) == 0;
}
nf_ct_refresh_acct(ct, ctinfo, skb, extra);
/* never set ASSURED for IPS_NAT_CLASH, they time out soon */
- if (unlikely((ct->status & IPS_NAT_CLASH)))
+ if (unlikely((status & IPS_NAT_CLASH)))
return NF_ACCEPT;
/* Also, more likely to be important, and not a probe */