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Diffstat (limited to 'target/linux/generic/patches-3.18/080-01-fib_trie-Fix-trie-balancing-issue-if-new-node-pushes.patch')
| -rw-r--r-- | target/linux/generic/patches-3.18/080-01-fib_trie-Fix-trie-balancing-issue-if-new-node-pushes.patch | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/target/linux/generic/patches-3.18/080-01-fib_trie-Fix-trie-balancing-issue-if-new-node-pushes.patch b/target/linux/generic/patches-3.18/080-01-fib_trie-Fix-trie-balancing-issue-if-new-node-pushes.patch new file mode 100644 index 0000000000..4e09f8a189 --- /dev/null +++ b/target/linux/generic/patches-3.18/080-01-fib_trie-Fix-trie-balancing-issue-if-new-node-pushes.patch @@ -0,0 +1,72 @@ +From: Alexander Duyck <alexander.h.duyck@redhat.com> +Date: Wed, 10 Dec 2014 21:49:22 -0800 +Subject: [PATCH] fib_trie: Fix trie balancing issue if new node pushes down + existing node + +This patch addresses an issue with the level compression of the fib_trie. +Specifically in the case of adding a new leaf that triggers a new node to +be added that takes the place of the old node. The result is a trie where +the 1 child tnode is on one side and one leaf is on the other which gives +you a very deep trie. Below is the script I used to generate a trie on +dummy0 with a 10.X.X.X family of addresses. + + ip link add type dummy + ipval=184549374 + bit=2 + for i in `seq 1 23` + do + ifconfig dummy0:$bit $ipval/8 + ipval=`expr $ipval - $bit` + bit=`expr $bit \* 2` + done + cat /proc/net/fib_triestat + +Running the script before the patch: + + Local: + Aver depth: 10.82 + Max depth: 23 + Leaves: 29 + Prefixes: 30 + Internal nodes: 27 + 1: 26 2: 1 + Pointers: 56 + Null ptrs: 1 + Total size: 5 kB + +After applying the patch and repeating: + + Local: + Aver depth: 4.72 + Max depth: 9 + Leaves: 29 + Prefixes: 30 + Internal nodes: 12 + 1: 3 2: 2 3: 7 + Pointers: 70 + Null ptrs: 30 + Total size: 4 kB + +What this fix does is start the rebalance at the newly created tnode +instead of at the parent tnode. This way if there is a gap between the +parent and the new node it doesn't prevent the new tnode from being +coalesced with any pre-existing nodes that may have been pushed into one +of the new nodes child branches. + +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 +@@ -1143,8 +1143,9 @@ static struct list_head *fib_insert_node + put_child(tp, cindex, (struct rt_trie_node *)tn); + } else { + rcu_assign_pointer(t->trie, (struct rt_trie_node *)tn); +- tp = tn; + } ++ ++ tp = tn; + } + + if (tp && tp->pos + tp->bits > 32) |