[SRU][J:linux-bluefield][PATCH] UBUNTU: SAUCE: netfilter: flowtable: additional checks for outdated flows

[Bodong Wang]

From: Vlad Buslov <vladbu at nvidia.com>

BugLink: https://bugs.launchpad.net/bugs/2029497

Current nf_flow_is_outdated() implementation considers any flow table flow
which state diverged from its underlying CT connection status for teardown
which can be problematic in the following cases:

- Flow has never been offloaded to hardware in the first place either
because flow table has hardware offload disabled (flag
NF_FLOWTABLE_HW_OFFLOAD is not set) or because it is still pending on 'add'
workqueue to be offloaded for the first time. The former is incorrect, the
later generates excessive deletions and additions of flows.

- Flow is already pending to be updated on the workqueue. Tearing down such
flows will also generate excessive removals from the flow table, especially
on highly loaded system where the latency to re-offload a flow via 'add'
workqueue can be quite high.

When considering a flow for teardown as outdated verify that it is both
offloaded to hardware and doesn't have any pending updates.

Fixes: 41f2c7c342d3 ("net/sched: act_ct: Fix promotion of offloaded unreplied tuple")
Signed-off-by: Vlad Buslov <vladbu at nvidia.com>
Signed-off-by: Bodong Wang <bodong at nvidia.com>
---
 net/netfilter/nf_flow_table_core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/netfilter/nf_flow_table_core.c b/net/netfilter/nf_flow_table_core.c
index d35f3f8d9841..d8f0f924b574 100644
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -342,6 +342,8 @@ EXPORT_SYMBOL_GPL(flow_offload_refresh);
 static bool nf_flow_is_outdated(const struct flow_offload *flow)
 {
 	return test_bit(IPS_SEEN_REPLY_BIT, &flow->ct->status) &&
+		test_bit(IPS_HW_OFFLOAD_BIT, &flow->ct->status) &&
+		!test_bit(NF_FLOW_HW_PENDING, &flow->flags) &&
 		!test_bit(NF_FLOW_HW_ESTABLISHED, &flow->flags);
 }
 
-- 
2.27.0