target/linux/generic/pending-5.15/704-00-netfilter-flowtable-fix-excessive-hw-offload-attempt.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Fri, 6 May 2022 12:37:23 +0200
   3 Subject: [PATCH] netfilter: flowtable: fix excessive hw offload attempts
   4  after failure
   5
   6 If a flow cannot be offloaded, the code currently repeatedly tries again as
   7 quickly as possible, which can significantly increase system load.
   8 Fix this by limiting flow timeout update and hardware offload retry to once
   9 per second.
  10
  11 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  12 ---
  13
  14 --- a/net/netfilter/nf_flow_table_core.c
  15 +++ b/net/netfilter/nf_flow_table_core.c
  16 @@ -329,8 +329,10 @@ void flow_offload_refresh(struct nf_flow
  17         u32 timeout;
  18
  19         timeout = nf_flowtable_time_stamp + flow_offload_get_timeout(flow);
  20 -       if (READ_ONCE(flow->timeout) != timeout)
  21 +       if (timeout - READ_ONCE(flow->timeout) > HZ)
  22                 WRITE_ONCE(flow->timeout, timeout);
  23 +       else
  24 +               return;
  25
  26         if (likely(!nf_flowtable_hw_offload(flow_table)))
  27                 return;