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Diffstat (limited to 'kernel/bpf/lpm_trie.c')
-rw-r--r--kernel/bpf/lpm_trie.c98
1 files changed, 94 insertions, 4 deletions
diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c
index 1b767844a76f..885e45479680 100644
--- a/kernel/bpf/lpm_trie.c
+++ b/kernel/bpf/lpm_trie.c
@@ -389,10 +389,99 @@ out:
return ret;
}
-static int trie_delete_elem(struct bpf_map *map, void *key)
+/* Called from syscall or from eBPF program */
+static int trie_delete_elem(struct bpf_map *map, void *_key)
{
- /* TODO */
- return -ENOSYS;
+ struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
+ struct bpf_lpm_trie_key *key = _key;
+ struct lpm_trie_node __rcu **trim, **trim2;
+ struct lpm_trie_node *node, *parent;
+ unsigned long irq_flags;
+ unsigned int next_bit;
+ size_t matchlen = 0;
+ int ret = 0;
+
+ if (key->prefixlen > trie->max_prefixlen)
+ return -EINVAL;
+
+ raw_spin_lock_irqsave(&trie->lock, irq_flags);
+
+ /* Walk the tree looking for an exact key/length match and keeping
+ * track of the path we traverse. We will need to know the node
+ * we wish to delete, and the slot that points to the node we want
+ * to delete. We may also need to know the nodes parent and the
+ * slot that contains it.
+ */
+ trim = &trie->root;
+ trim2 = trim;
+ parent = NULL;
+ while ((node = rcu_dereference_protected(
+ *trim, lockdep_is_held(&trie->lock)))) {
+ matchlen = longest_prefix_match(trie, node, key);
+
+ if (node->prefixlen != matchlen ||
+ node->prefixlen == key->prefixlen)
+ break;
+
+ parent = node;
+ trim2 = trim;
+ next_bit = extract_bit(key->data, node->prefixlen);
+ trim = &node->child[next_bit];
+ }
+
+ if (!node || node->prefixlen != key->prefixlen ||
+ (node->flags & LPM_TREE_NODE_FLAG_IM)) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ trie->n_entries--;
+
+ /* If the node we are removing has two children, simply mark it
+ * as intermediate and we are done.
+ */
+ if (rcu_access_pointer(node->child[0]) &&
+ rcu_access_pointer(node->child[1])) {
+ node->flags |= LPM_TREE_NODE_FLAG_IM;
+ goto out;
+ }
+
+ /* If the parent of the node we are about to delete is an intermediate
+ * node, and the deleted node doesn't have any children, we can delete
+ * the intermediate parent as well and promote its other child
+ * up the tree. Doing this maintains the invariant that all
+ * intermediate nodes have exactly 2 children and that there are no
+ * unnecessary intermediate nodes in the tree.
+ */
+ if (parent && (parent->flags & LPM_TREE_NODE_FLAG_IM) &&
+ !node->child[0] && !node->child[1]) {
+ if (node == rcu_access_pointer(parent->child[0]))
+ rcu_assign_pointer(
+ *trim2, rcu_access_pointer(parent->child[1]));
+ else
+ rcu_assign_pointer(
+ *trim2, rcu_access_pointer(parent->child[0]));
+ kfree_rcu(parent, rcu);
+ kfree_rcu(node, rcu);
+ goto out;
+ }
+
+ /* The node we are removing has either zero or one child. If there
+ * is a child, move it into the removed node's slot then delete
+ * the node. Otherwise just clear the slot and delete the node.
+ */
+ if (node->child[0])
+ rcu_assign_pointer(*trim, rcu_access_pointer(node->child[0]));
+ else if (node->child[1])
+ rcu_assign_pointer(*trim, rcu_access_pointer(node->child[1]));
+ else
+ RCU_INIT_POINTER(*trim, NULL);
+ kfree_rcu(node, rcu);
+
+out:
+ raw_spin_unlock_irqrestore(&trie->lock, irq_flags);
+
+ return ret;
}
#define LPM_DATA_SIZE_MAX 256
@@ -406,7 +495,8 @@ static int trie_delete_elem(struct bpf_map *map, void *key)
#define LPM_KEY_SIZE_MAX LPM_KEY_SIZE(LPM_DATA_SIZE_MAX)
#define LPM_KEY_SIZE_MIN LPM_KEY_SIZE(LPM_DATA_SIZE_MIN)
-#define LPM_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_NUMA_NODE)
+#define LPM_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_NUMA_NODE | \
+ BPF_F_RDONLY | BPF_F_WRONLY)
static struct bpf_map *trie_alloc(union bpf_attr *attr)
{