target/linux/generic/patches-3.18/080-25-fib_trie-Various-clean-ups-for-handling-slen.patch

   1 From: Alexander Duyck <alexander.h.duyck@redhat.com>
   2 Date: Thu, 22 Jan 2015 15:51:45 -0800
   3 Subject: [PATCH] fib_trie: Various clean-ups for handling slen
   4
   5 While doing further work on the fib_trie I noted a few items.
   6
   7 First I was using calls that were far more complicated than they needed to
   8 be for determining when to push/pull the suffix length.  I have updated the
   9 code to reflect the simplier logic.
  10
  11 The second issue is that I realised we weren't necessarily handling the
  12 case of a leaf_info struct surviving a flush.  I have updated the logic so
  13 that now we will call pull_suffix in the event of having a leaf info value
  14 left in the leaf after flushing it.
  15
  16 Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
  17 Signed-off-by: David S. Miller <davem@davemloft.net>
  18 ---
  19
  20 --- a/net/ipv4/fib_trie.c
  21 +++ b/net/ipv4/fib_trie.c
  22 @@ -917,27 +917,20 @@ static void leaf_push_suffix(struct tnod
  23
  24  static void remove_leaf_info(struct tnode *l, struct leaf_info *old)
  25  {
  26 -       struct hlist_node *prev;
  27 -
  28 -       /* record the location of the pointer to this object */
  29 -       prev = rtnl_dereference(hlist_pprev_rcu(&old->hlist));
  30 +       /* record the location of the previous list_info entry */
  31 +       struct hlist_node **pprev = old->hlist.pprev;
  32 +       struct leaf_info *li = hlist_entry(pprev, typeof(*li), hlist.next);
  33
  34         /* remove the leaf info from the list */
  35         hlist_del_rcu(&old->hlist);
  36
  37 -       /* if we emptied the list this leaf will be freed and we can sort
  38 -        * out parent suffix lengths as a part of trie_rebalance
  39 -        */
  40 -       if (hlist_empty(&l->list))
  41 +       /* only access li if it is pointing at the last valid hlist_node */
  42 +       if (hlist_empty(&l->list) || (*pprev))
  43                 return;
  44
  45 -       /* if we removed the tail then we need to update slen */
  46 -       if (!rcu_access_pointer(hlist_next_rcu(prev))) {
  47 -               struct leaf_info *li = hlist_entry(prev, typeof(*li), hlist);
  48 -
  49 -               l->slen = KEYLENGTH - li->plen;
  50 -               leaf_pull_suffix(l);
  51 -       }
  52 +       /* update the trie with the latest suffix length */
  53 +       l->slen = KEYLENGTH - li->plen;
  54 +       leaf_pull_suffix(l);
  55  }
  56
  57  static void insert_leaf_info(struct tnode *l, struct leaf_info *new)
  58 @@ -961,7 +954,7 @@ static void insert_leaf_info(struct tnod
  59         }
  60
  61         /* if we added to the tail node then we need to update slen */
  62 -       if (!rcu_access_pointer(hlist_next_rcu(&new->hlist))) {
  63 +       if (l->slen < (KEYLENGTH - new->plen)) {
  64                 l->slen = KEYLENGTH - new->plen;
  65                 leaf_push_suffix(l);
  66         }
  67 @@ -1613,6 +1606,7 @@ static int trie_flush_leaf(struct tnode
  68         struct hlist_head *lih = &l->list;
  69         struct hlist_node *tmp;
  70         struct leaf_info *li = NULL;
  71 +       unsigned char plen = KEYLENGTH;
  72
  73         hlist_for_each_entry_safe(li, tmp, lih, hlist) {
  74                 found += trie_flush_list(&li->falh);
  75 @@ -1620,8 +1614,14 @@ static int trie_flush_leaf(struct tnode
  76                 if (list_empty(&li->falh)) {
  77                         hlist_del_rcu(&li->hlist);
  78                         free_leaf_info(li);
  79 +                       continue;
  80                 }
  81 +
  82 +               plen = li->plen;
  83         }
  84 +
  85 +       l->slen = KEYLENGTH - plen;
  86 +
  87         return found;
  88  }
  89
  90 @@ -1700,13 +1700,22 @@ int fib_table_flush(struct fib_table *tb
  91         for (l = trie_firstleaf(t); l; l = trie_nextleaf(l)) {
  92                 found += trie_flush_leaf(l);
  93
  94 -               if (ll && hlist_empty(&ll->list))
  95 -                       trie_leaf_remove(t, ll);
  96 +               if (ll) {
  97 +                       if (hlist_empty(&ll->list))
  98 +                               trie_leaf_remove(t, ll);
  99 +                       else
 100 +                               leaf_pull_suffix(ll);
 101 +               }
 102 +
 103                 ll = l;
 104         }
 105
 106 -       if (ll && hlist_empty(&ll->list))
 107 -               trie_leaf_remove(t, ll);
 108 +       if (ll) {
 109 +               if (hlist_empty(&ll->list))
 110 +                       trie_leaf_remove(t, ll);
 111 +               else
 112 +                       leaf_pull_suffix(ll);
 113 +       }
 114
 115         pr_debug("trie_flush found=%d\n", found);
 116         return found;