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authorHerbert Xu <herbert@gondor.apana.org.au>2005-10-15 09:42:39 +1000
committerArnaldo Carvalho de Melo <acme@mandriva.com>2005-10-26 00:25:03 -0200
commit1371e37da299d4df6267ad0ddf010435782c28e9 (patch)
treea8b1706d73d86e5f732b132d99b90e1107eafb68
parenteed75f191d8318a2b144da8aae9774e1cfcae492 (diff)
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[IPV4]: Kill redundant rcu_dereference on fa_info
This patch kills a redundant rcu_dereference on fa->fa_info in fib_trie.c. As this dereference directly follows a list_for_each_entry_rcu line, we have already taken a read barrier with respect to getting an entry from the list. This read barrier guarantees that all values read out of fa are valid. In particular, the contents of structure pointed to by fa->fa_info is initialised before fa->fa_info is actually set (see fn_trie_insert); the setting of fa->fa_info itself is further separated with a write barrier from the insertion of fa into the list. Therefore by taking a read barrier after obtaining fa from the list (which is given by list_for_each_entry_rcu), we can be sure that fa->fa_info contains a valid pointer, as well as the fact that the data pointed to by fa->fa_info is itself valid. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Paul E. McKenney <paulmck@us.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
-rw-r--r--net/ipv4/fib_trie.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 0093ea0..66247f3 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -2404,7 +2404,7 @@ static int fib_route_seq_show(struct seq_file *seq, void *v)
prefix = htonl(l->key);
list_for_each_entry_rcu(fa, &li->falh, fa_list) {
- const struct fib_info *fi = rcu_dereference(fa->fa_info);
+ const struct fib_info *fi = fa->fa_info;
unsigned flags = fib_flag_trans(fa->fa_type, mask, fi);
if (fa->fa_type == RTN_BROADCAST