1. 14 Jun, 2013 1 commit
    • Willem de Bruijn's avatar
      net-rps: fixes for rps flow limit · 5f121b9a
      Willem de Bruijn authored
      Caught by sparse:
      - __rcu: missing annotation to sd->flow_limit
      - __user: direct access in cpumask_scnprintf
      
      Also
      - add endline character when printing bitmap if room in buffer
      - avoid bucket overflow by reducing FLOW_LIMIT_HISTORY
      
      The last item warrants some explanation. The hashtable buckets are
      subject to overflow if FLOW_LIMIT_HISTORY is larger than or equal
      to bucket size, since all packets may end up in a single bucket. The
      current (rather arbitrary) history value of 256 happens to match the
      buffer size (u8).
      
      As a result, with a single flow, the first 128 packets are accepted
      (correct), the second 128 packets dropped (correct) and then the
      history[] array has filled, so that each subsequent new packet
      causes an increment in the bucket for new_flow plus a decrement
      for old_flow: a steady state.
      
      This is fine if packets are dropped, as the steady state goes away
      as soon as a mix of traffic reappears. But, because the 256th packet
      overflowed the bucket to 0: no packets are dropped.
      
      Instead of explicitly adding an overflow check, this patch changes
      FLOW_LIMIT_HISTORY to never be able to overflow a single bucket.
      Reported-by: default avatarFengguang Wu <fengguang.wu@intel.com>
      (first item)
      Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      5f121b9a
  2. 13 Jun, 2013 10 commits
  3. 12 Jun, 2013 26 commits
  4. 11 Jun, 2013 3 commits