kernel: backport fib_trie improvements/fixes from 4.0-rc

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@44695 3c298f89-4303-0410-b956-a3cf2f4a3e73

1 files changed, 34 insertions, 0 deletions

diff --git a/target/linux/generic/patches-3.18/080-23-fib_trie-Use-empty_children-instead-of-counting-empt.patch b/target/linux/generic/patches-3.18/080-23-fib_trie-Use-empty_children-instead-of-counting-empt.patch
new file mode 100644
index 0000000000..160fbe1f3e
--- /dev/null
+++ b/target/linux/generic/patches-3.18/080-23-fib_trie-Use-empty_children-instead-of-counting-empt.patch
@@ -0,0 +1,34 @@
+From: Alexander Duyck <alexander.h.duyck@redhat.com>
+Date: Thu, 22 Jan 2015 15:51:33 -0800
+Subject: [PATCH] fib_trie: Use empty_children instead of counting empty nodes
+ in stats collection
+
+It doesn't make much sense to count the pointers ourselves when
+empty_children already has a count for the number of NULL pointers stored
+in the tnode.  As such save ourselves the cycles and just use
+empty_children.
+
+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
+@@ -1954,16 +1954,10 @@ static void trie_collect_stats(struct tr
+ 			hlist_for_each_entry_rcu(li, &n->list, hlist)
+ 				++s->prefixes;
+ 		} else {
+-			unsigned long i;
+-
+ 			s->tnodes++;
+ 			if (n->bits < MAX_STAT_DEPTH)
+ 				s->nodesizes[n->bits]++;
+-
+-			for (i = tnode_child_length(n); i--;) {
+-				if (!rcu_access_pointer(n->child[i]))
+-					s->nullpointers++;
+-			}
++			s->nullpointers += n->empty_children;
+ 		}
+ 	}
+ 	rcu_read_unlock();