mirror of
https://github.com/openwrt/openwrt.git
synced 2024-12-30 10:39:04 +00:00
73 lines
2.0 KiB
Diff
73 lines
2.0 KiB
Diff
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)
|