releases/3.6.8/net-rps-fix-brokeness-causing-ooo-packets.patch

   1 From 5e26fb0e61c630f44d4cdd09e5c190647e4aa0f3 Mon Sep 17 00:00:00 2001
   2 From: Tom Herbert <therbert@google.com>
   3 Date: Fri, 16 Nov 2012 09:04:15 +0000
   4 Subject: net-rps: Fix brokeness causing OOO packets
   5
   6
   7 From: Tom Herbert <therbert@google.com>
   8
   9 [ Upstream commit baefa31db2f2b13a05d1b81bdf2d20d487f58b0a ]
  10
  11 In commit c445477d74ab3779 which adds aRFS to the kernel, the CPU
  12 selected for RFS is not set correctly when CPU is changing.
  13 This is causing OOO packets and probably other issues.
  14
  15 Signed-off-by: Tom Herbert <therbert@google.com>
  16 Acked-by: Eric Dumazet <edumazet@google.com>
  17 Acked-by: Ben Hutchings <bhutchings@solarflare.com>
  18 Signed-off-by: David S. Miller <davem@davemloft.net>
  19 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  20 ---
  21  net/core/dev.c |    4 +++-
  22  1 file changed, 3 insertions(+), 1 deletion(-)
  23
  24 --- a/net/core/dev.c
  25 +++ b/net/core/dev.c
  26 @@ -2793,8 +2793,10 @@ static int get_rps_cpu(struct net_device
  27                 if (unlikely(tcpu != next_cpu) &&
  28                     (tcpu == RPS_NO_CPU || !cpu_online(tcpu) ||
  29                      ((int)(per_cpu(softnet_data, tcpu).input_queue_head -
  30 -                     rflow->last_qtail)) >= 0))
  31 +                     rflow->last_qtail)) >= 0)) {
  32 +                       tcpu = next_cpu;
  33                         rflow = set_rps_cpu(dev, skb, rflow, next_cpu);
  34 +               }
  35
  36                 if (tcpu != RPS_NO_CPU && cpu_online(tcpu)) {
  37                         *rflowp = rflow;