kernel: backport fib_trie improvements/fixes from 4.0-rc

[15.05/openwrt.git] / target / linux / generic / patches-3.18 / 080-25-fib_trie-Various-clean-ups-for-handling-slen.patch

diff --git a/target/linux/generic/patches-3.18/080-25-fib_trie-Various-clean-ups-for-handling-slen.patch b/target/linux/generic/patches-3.18/080-25-fib_trie-Various-clean-ups-for-handling-slen.patch
new file mode 100644 (file)
index 0000000..e47f253
--- /dev/null
+++ b/target/linux/generic/patches-3.18/080-25-fib_trie-Various-clean-ups-for-handling-slen.patch
@@ -0,0 +1,116 @@
+From: Alexander Duyck <alexander.h.duyck@redhat.com>
+Date: Thu, 22 Jan 2015 15:51:45 -0800
+Subject: [PATCH] fib_trie: Various clean-ups for handling slen
+
+While doing further work on the fib_trie I noted a few items.
+
+First I was using calls that were far more complicated than they needed to
+be for determining when to push/pull the suffix length.  I have updated the
+code to reflect the simplier logic.
+
+The second issue is that I realised we weren't necessarily handling the
+case of a leaf_info struct surviving a flush.  I have updated the logic so
+that now we will call pull_suffix in the event of having a leaf info value
+left in the leaf after flushing it.
+
+Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+
+--- a/net/ipv4/fib_trie.c
++++ b/net/ipv4/fib_trie.c
+@@ -917,27 +917,20 @@ static void leaf_push_suffix(struct tnod
+ 
+ static void remove_leaf_info(struct tnode *l, struct leaf_info *old)
+ {
+-      struct hlist_node *prev;
+-
+-      /* record the location of the pointer to this object */
+-      prev = rtnl_dereference(hlist_pprev_rcu(&old->hlist));
++      /* record the location of the previous list_info entry */
++      struct hlist_node **pprev = old->hlist.pprev;
++      struct leaf_info *li = hlist_entry(pprev, typeof(*li), hlist.next);
+ 
+       /* remove the leaf info from the list */
+       hlist_del_rcu(&old->hlist);
+ 
+-      /* if we emptied the list this leaf will be freed and we can sort
+-       * out parent suffix lengths as a part of trie_rebalance
+-       */
+-      if (hlist_empty(&l->list))
++      /* only access li if it is pointing at the last valid hlist_node */
++      if (hlist_empty(&l->list) || (*pprev))
+               return;
+ 
+-      /* if we removed the tail then we need to update slen */
+-      if (!rcu_access_pointer(hlist_next_rcu(prev))) {
+-              struct leaf_info *li = hlist_entry(prev, typeof(*li), hlist);
+-
+-              l->slen = KEYLENGTH - li->plen;
+-              leaf_pull_suffix(l);
+-      }
++      /* update the trie with the latest suffix length */
++      l->slen = KEYLENGTH - li->plen;
++      leaf_pull_suffix(l);
+ }
+ 
+ static void insert_leaf_info(struct tnode *l, struct leaf_info *new)
+@@ -961,7 +954,7 @@ static void insert_leaf_info(struct tnod
+       }
+ 
+       /* if we added to the tail node then we need to update slen */
+-      if (!rcu_access_pointer(hlist_next_rcu(&new->hlist))) {
++      if (l->slen < (KEYLENGTH - new->plen)) {
+               l->slen = KEYLENGTH - new->plen;
+               leaf_push_suffix(l);
+       }
+@@ -1613,6 +1606,7 @@ static int trie_flush_leaf(struct tnode 
+       struct hlist_head *lih = &l->list;
+       struct hlist_node *tmp;
+       struct leaf_info *li = NULL;
++      unsigned char plen = KEYLENGTH;
+ 
+       hlist_for_each_entry_safe(li, tmp, lih, hlist) {
+               found += trie_flush_list(&li->falh);
+@@ -1620,8 +1614,14 @@ static int trie_flush_leaf(struct tnode 
+               if (list_empty(&li->falh)) {
+                       hlist_del_rcu(&li->hlist);
+                       free_leaf_info(li);
++                      continue;
+               }
++
++              plen = li->plen;
+       }
++
++      l->slen = KEYLENGTH - plen;
++
+       return found;
+ }
+ 
+@@ -1700,13 +1700,22 @@ int fib_table_flush(struct fib_table *tb
+       for (l = trie_firstleaf(t); l; l = trie_nextleaf(l)) {
+               found += trie_flush_leaf(l);
+ 
+-              if (ll && hlist_empty(&ll->list))
+-                      trie_leaf_remove(t, ll);
++              if (ll) {
++                      if (hlist_empty(&ll->list))
++                              trie_leaf_remove(t, ll);
++                      else
++                              leaf_pull_suffix(ll);
++              }
++
+               ll = l;
+       }
+ 
+-      if (ll && hlist_empty(&ll->list))
+-              trie_leaf_remove(t, ll);
++      if (ll) {
++              if (hlist_empty(&ll->list))
++                      trie_leaf_remove(t, ll);
++              else
++                      leaf_pull_suffix(ll);
++      }
+ 
+       pr_debug("trie_flush found=%d\n", found);
+       return found;