On 12/15/2015 12:21 PM, Ming Lei wrote:
...
+static int htab_init_elems_allocator(struct bpf_htab *htab)
+{
+ int ret = htab_pre_alloc_elems(htab);
+
+ if (ret)
+ return ret;
+
+ ret = percpu_ida_init(&htab->elems_pool, htab->map.max_entries);
+ if (ret)
+ htab_destroy_elems(htab);
+ return ret;
+}
+
+static void htab_deinit_elems_allocator(struct bpf_htab *htab)
+{
+ htab_destroy_elems(htab);
+ percpu_ida_destroy(&htab->elems_pool);
+}
+
+static struct htab_elem *htab_alloc_elem(struct bpf_htab *htab)
+{
+ int tag = percpu_ida_alloc(&htab->elems_pool, TASK_RUNNING);
+ struct htab_elem *elem;
+
+ if (tag < 0)
+ return NULL;
+
+ elem = htab->elems[tag];
+ elem->tag = tag;
+ return elem;
+}
....
@@ -285,12 +424,8 @@ static int htab_map_update_elem(struct bpf_map *map, void
*key, void *value,
* search will find it before old elem
*/
hlist_add_head_rcu_lock(&l_new->hash_node, head);
- if (l_old) {
- hlist_del_rcu_lock(&l_old->hash_node);
- kfree_rcu(l_old, rcu);
- } else {
- atomic_inc(&htab->count);
- }
+ if (l_old)
+ htab_free_elem_rcu(htab, l_old);
bit_spin_unlock(HLIST_LOCK_BIT, (unsigned long *)&head->first);
raw_local_irq_restore(flags);
On a quick look, you are using the ida to keep track of elements, right? What
happens
if you have a hash-table of max_entry size 1, fill that one slot and later on
try to
replace it with a different element.
Old behaviour (htab->count) doesn't increase htab count and would allow the
replacement
of that element to happen.
Looks like in your case, we'd get -E2BIG from htab_alloc_elem(), no? ... as
preallocated
pool is already used up then?
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