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authorEric Dumazet <dada1@cosmosbay.com>2008-01-18 03:31:36 -0800
committerDavid S. Miller <davem@davemloft.net>2008-01-28 15:02:45 -0800
commitb59cfbf77dc8368c2c90b012c79553613f4d70c3 (patch)
treef5e2e9ffa576c80137126e7ebe70114b88d98003
parent95b7d924a589dbefc7ae2ea6c7144b86b75d6a47 (diff)
[FIB]: Fix rcu_dereference() abuses in fib_trie.c
node_parent() and tnode_get_child() currently use rcu_dereference(). These functions are called from both - readers only paths (where rcu_dereference() is needed), and - writer path (where rcu_dereference() is not needed) To make explicit where rcu_dereference() is really needed, I introduced new node_parent_rcu() and tnode_get_child_rcu() functions which use rcu_dereference(), while node_parent() and tnode_get_child() dont use it. Then I changed calling sites where rcu_dereference() was really needed to call the _rcu() variants. This should have no impact but for alpha architecture, and may help future sparse checks. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/fib_trie.c33
1 files changed, 21 insertions, 12 deletions
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index fbc80d15827..a52334d30cf 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -165,9 +165,13 @@ static struct kmem_cache *fn_alias_kmem __read_mostly;
static inline struct tnode *node_parent(struct node *node)
{
- struct tnode *ret;
+ return (struct tnode *)(node->parent & ~NODE_TYPE_MASK);
+}
+
+static inline struct tnode *node_parent_rcu(struct node *node)
+{
+ struct tnode *ret = node_parent(node);
- ret = (struct tnode *)(node->parent & ~NODE_TYPE_MASK);
return rcu_dereference(ret);
}
@@ -177,13 +181,18 @@ static inline void node_set_parent(struct node *node, struct tnode *ptr)
(unsigned long)ptr | NODE_TYPE(node));
}
-/* rcu_read_lock needs to be hold by caller from readside */
+static inline struct node *tnode_get_child(struct tnode *tn, unsigned int i)
+{
+ BUG_ON(i >= 1U << tn->bits);
-static inline struct node *tnode_get_child(struct tnode *tn, int i)
+ return tn->child[i];
+}
+
+static inline struct node *tnode_get_child_rcu(struct tnode *tn, unsigned int i)
{
- BUG_ON(i >= 1 << tn->bits);
+ struct node *ret = tnode_get_child(tn, i);
- return rcu_dereference(tn->child[i]);
+ return rcu_dereference(ret);
}
static inline int tnode_child_length(const struct tnode *tn)
@@ -938,7 +947,7 @@ fib_find_node(struct trie *t, u32 key)
if (tkey_sub_equals(tn->key, pos, tn->pos-pos, key)) {
pos = tn->pos + tn->bits;
- n = tnode_get_child(tn, tkey_extract_bits(key, tn->pos, tn->bits));
+ n = tnode_get_child_rcu(tn, tkey_extract_bits(key, tn->pos, tn->bits));
} else
break;
}
@@ -1688,7 +1697,7 @@ static struct leaf *nextleaf(struct trie *t, struct leaf *thisleaf)
p = (struct tnode*) trie; /* Start */
} else
- p = node_parent(c);
+ p = node_parent_rcu(c);
while (p) {
int pos, last;
@@ -1725,7 +1734,7 @@ static struct leaf *nextleaf(struct trie *t, struct leaf *thisleaf)
up:
/* No more children go up one step */
c = (struct node *) p;
- p = node_parent(c);
+ p = node_parent_rcu(c);
}
return NULL; /* Ready. Root of trie */
}
@@ -1987,7 +1996,7 @@ static struct node *fib_trie_get_next(struct fib_trie_iter *iter)
iter->tnode, iter->index, iter->depth);
rescan:
while (cindex < (1<<tn->bits)) {
- struct node *n = tnode_get_child(tn, cindex);
+ struct node *n = tnode_get_child_rcu(tn, cindex);
if (n) {
if (IS_LEAF(n)) {
@@ -2006,7 +2015,7 @@ rescan:
}
/* Current node exhausted, pop back up */
- p = node_parent((struct node *)tn);
+ p = node_parent_rcu((struct node *)tn);
if (p) {
cindex = tkey_extract_bits(tn->key, p->pos, p->bits)+1;
tn = p;
@@ -2315,7 +2324,7 @@ static int fib_trie_seq_show(struct seq_file *seq, void *v)
if (v == SEQ_START_TOKEN)
return 0;
- if (!node_parent(n)) {
+ if (!node_parent_rcu(n)) {
if (iter->trie == iter->trie_local)
seq_puts(seq, "<local>:\n");
else