queue-5.0/sch_cake-simplify-logic-in-cake_select_tin.patch

   1 From foo@baz Sat Apr 20 16:43:09 CEST 2019
   2 From: "Toke Høiland-Jørgensen" <toke@redhat.com>
   3 Date: Fri, 5 Apr 2019 15:01:59 +0200
   4 Subject: sch_cake: Simplify logic in cake_select_tin()
   5
   6 From: "Toke Høiland-Jørgensen" <toke@redhat.com>
   7
   8 [ Upstream commit 4976e3c683f328bc6f2edef555a4ffee6524486f ]
   9
  10 The logic in cake_select_tin() was getting a bit hairy, and it turns out we
  11 can simplify it quite a bit. This also allows us to get rid of one of the
  12 two diffserv parsing functions, which has the added benefit that
  13 already-zeroed DSCP fields won't get re-written.
  14
  15 Suggested-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
  16 Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
  17 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  18 ---
  19  net/sched/sch_cake.c |   44 ++++++++++++++++----------------------------
  20  1 file changed, 16 insertions(+), 28 deletions(-)
  21
  22 --- a/net/sched/sch_cake.c
  23 +++ b/net/sched/sch_cake.c
  24 @@ -1508,20 +1508,6 @@ static unsigned int cake_drop(struct Qdi
  25         return idx + (tin << 16);
  26  }
  27
  28 -static void cake_wash_diffserv(struct sk_buff *skb)
  29 -{
  30 -       switch (skb->protocol) {
  31 -       case htons(ETH_P_IP):
  32 -               ipv4_change_dsfield(ip_hdr(skb), INET_ECN_MASK, 0);
  33 -               break;
  34 -       case htons(ETH_P_IPV6):
  35 -               ipv6_change_dsfield(ipv6_hdr(skb), INET_ECN_MASK, 0);
  36 -               break;
  37 -       default:
  38 -               break;
  39 -       }
  40 -}
  41 -
  42  static u8 cake_handle_diffserv(struct sk_buff *skb, u16 wash)
  43  {
  44         int wlen = skb_network_offset(skb);
  45 @@ -1564,25 +1550,27 @@ static struct cake_tin_data *cake_select
  46  {
  47         struct cake_sched_data *q = qdisc_priv(sch);
  48         u32 tin;
  49 +       u8 dscp;
  50 +
  51 +       /* Tin selection: Default to diffserv-based selection, allow overriding
  52 +        * using firewall marks or skb->priority.
  53 +        */
  54 +       dscp = cake_handle_diffserv(skb,
  55 +                                   q->rate_flags & CAKE_FLAG_WASH);
  56 +
  57 +       if (q->tin_mode == CAKE_DIFFSERV_BESTEFFORT)
  58 +               tin = 0;
  59
  60 -       if (TC_H_MAJ(skb->priority) == sch->handle &&
  61 -           TC_H_MIN(skb->priority) > 0 &&
  62 -           TC_H_MIN(skb->priority) <= q->tin_cnt) {
  63 +       else if (TC_H_MAJ(skb->priority) == sch->handle &&
  64 +                TC_H_MIN(skb->priority) > 0 &&
  65 +                TC_H_MIN(skb->priority) <= q->tin_cnt)
  66                 tin = q->tin_order[TC_H_MIN(skb->priority) - 1];
  67
  68 -               if (q->rate_flags & CAKE_FLAG_WASH)
  69 -                       cake_wash_diffserv(skb);
  70 -       } else if (q->tin_mode != CAKE_DIFFSERV_BESTEFFORT) {
  71 -               /* extract the Diffserv Precedence field, if it exists */
  72 -               /* and clear DSCP bits if washing */
  73 -               tin = q->tin_index[cake_handle_diffserv(skb,
  74 -                               q->rate_flags & CAKE_FLAG_WASH)];
  75 +       else {
  76 +               tin = q->tin_index[dscp];
  77 +
  78                 if (unlikely(tin >= q->tin_cnt))
  79                         tin = 0;
  80 -       } else {
  81 -               tin = 0;
  82 -               if (q->rate_flags & CAKE_FLAG_WASH)
  83 -                       cake_wash_diffserv(skb);
  84         }
  85
  86         return &q->tins[tin];