Hi Daniel,

On 01/05/2017 09:04 PM, Daniel Mack wrote:

On 01/05/2017 05:25 PM, Daniel Borkmann wrote:

quoted

On 12/29/2016 06:28 PM, Daniel Mack wrote:

quoted

quoted

diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c
new file mode 100644
index 0000000..8b6a61d
--- /dev/null
+++ b/kernel/bpf/lpm_trie.c

[..]

quoted

quoted

+static struct bpf_map *trie_alloc(union bpf_attr *attr)
+{
+	struct lpm_trie *trie;
+
+	/* check sanity of attributes */
+	if (attr->max_entries == 0 || attr->map_flags ||
+	    attr->key_size < sizeof(struct bpf_lpm_trie_key) + 1   ||
+	    attr->key_size > sizeof(struct bpf_lpm_trie_key) + 256 ||
+	    attr->value_size != sizeof(u64))
+		return ERR_PTR(-EINVAL);

The correct attr->map_flags test here would need to be ...

    attr->map_flags != BPF_F_NO_PREALLOC

... since in this case we don't have any prealloc pool, and
should that come one day that test could be relaxed again.

quoted

+	trie = kzalloc(sizeof(*trie), GFP_USER | __GFP_NOWARN);
+	if (!trie)
+		return NULL;
+
+	/* copy mandatory map attributes */
+	trie->map.map_type = attr->map_type;
+	trie->map.key_size = attr->key_size;
+	trie->map.value_size = attr->value_size;
+	trie->map.max_entries = attr->max_entries;

You also need to fill in trie->map.pages as that is eventually
used to charge memory against in bpf_map_charge_memlock(), right
now that would remain as 0 meaning the map is not accounted for.

Hmm, okay. The nodes are, however, allocated dynamically at runtime in
this case. That means that we have trie->map.pages on each allocation,
right?

The current scheme (f.e. htab_map_alloc() has some details, although
probably not too obvious) that was done charges worst-case cost up front,
so it would be in trie_alloc() where you fill map.pages and map_create()
will later account for them.

Thanks,
Daniel