releases/4.4.133/net_sched-fq-take-care-of-throttled-flows-before-reuse.patch

   1 From foo@baz Wed May 16 16:57:32 CEST 2018
   2 From: Eric Dumazet <edumazet@google.com>
   3 Date: Wed, 2 May 2018 10:03:30 -0700
   4 Subject: net_sched: fq: take care of throttled flows before reuse
   5
   6 From: Eric Dumazet <edumazet@google.com>
   7
   8 [ Upstream commit 7df40c2673a1307c3260aab6f9d4b9bf97ca8fd7 ]
   9
  10 Normally, a socket can not be freed/reused unless all its TX packets
  11 left qdisc and were TX-completed. However connect(AF_UNSPEC) allows
  12 this to happen.
  13
  14 With commit fc59d5bdf1e3 ("pkt_sched: fq: clear time_next_packet for
  15 reused flows") we cleared f->time_next_packet but took no special
  16 action if the flow was still in the throttled rb-tree.
  17
  18 Since f->time_next_packet is the key used in the rb-tree searches,
  19 blindly clearing it might break rb-tree integrity. We need to make
  20 sure the flow is no longer in the rb-tree to avoid this problem.
  21
  22 Fixes: fc59d5bdf1e3 ("pkt_sched: fq: clear time_next_packet for reused flows")
  23 Signed-off-by: Eric Dumazet <edumazet@google.com>
  24 Signed-off-by: David S. Miller <davem@davemloft.net>
  25 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  26 ---
  27  net/sched/sch_fq.c |   37 +++++++++++++++++++++++++------------
  28  1 file changed, 25 insertions(+), 12 deletions(-)
  29
  30 --- a/net/sched/sch_fq.c
  31 +++ b/net/sched/sch_fq.c
  32 @@ -126,6 +126,28 @@ static bool fq_flow_is_detached(const st
  33         return f->next == &detached;
  34  }
  35
  36 +static bool fq_flow_is_throttled(const struct fq_flow *f)
  37 +{
  38 +       return f->next == &throttled;
  39 +}
  40 +
  41 +static void fq_flow_add_tail(struct fq_flow_head *head, struct fq_flow *flow)
  42 +{
  43 +       if (head->first)
  44 +               head->last->next = flow;
  45 +       else
  46 +               head->first = flow;
  47 +       head->last = flow;
  48 +       flow->next = NULL;
  49 +}
  50 +
  51 +static void fq_flow_unset_throttled(struct fq_sched_data *q, struct fq_flow *f)
  52 +{
  53 +       rb_erase(&f->rate_node, &q->delayed);
  54 +       q->throttled_flows--;
  55 +       fq_flow_add_tail(&q->old_flows, f);
  56 +}
  57 +
  58  static void fq_flow_set_throttled(struct fq_sched_data *q, struct fq_flow *f)
  59  {
  60         struct rb_node **p = &q->delayed.rb_node, *parent = NULL;
  61 @@ -153,15 +175,6 @@ static void fq_flow_set_throttled(struct
  62
  63  static struct kmem_cache *fq_flow_cachep __read_mostly;
  64
  65 -static void fq_flow_add_tail(struct fq_flow_head *head, struct fq_flow *flow)
  66 -{
  67 -       if (head->first)
  68 -               head->last->next = flow;
  69 -       else
  70 -               head->first = flow;
  71 -       head->last = flow;
  72 -       flow->next = NULL;
  73 -}
  74
  75  /* limit number of collected flows per round */
  76  #define FQ_GC_MAX 8
  77 @@ -265,6 +278,8 @@ static struct fq_flow *fq_classify(struc
  78                                      f->socket_hash != sk->sk_hash)) {
  79                                 f->credit = q->initial_quantum;
  80                                 f->socket_hash = sk->sk_hash;
  81 +                               if (fq_flow_is_throttled(f))
  82 +                                       fq_flow_unset_throttled(q, f);
  83                                 f->time_next_packet = 0ULL;
  84                         }
  85                         return f;
  86 @@ -419,9 +434,7 @@ static void fq_check_throttled(struct fq
  87                         q->time_next_delayed_flow = f->time_next_packet;
  88                         break;
  89                 }
  90 -               rb_erase(p, &q->delayed);
  91 -               q->throttled_flows--;
  92 -               fq_flow_add_tail(&q->old_flows, f);
  93 +               fq_flow_unset_throttled(q, f);
  94         }
  95  }
  96