[RFC PATCH 2/6] bpf: Add function map->ops->map_traverse_elem() to traverse map elems

kaixu xia
2015-07-17T10:46:54Z

Sometimes we want to traverse the map elements and make use
of the map value one by one. So add new function
map->ops->map_traverse_elem() to traverse map elements.

Signed-off-by: kaixu xia <xiakaixu@huawei.com>
---
include/linux/bpf.h | 3 +++
kernel/bpf/arraymap.c | 17 +++++++++++++++++
kernel/bpf/hashtab.c | 27 +++++++++++++++++++++++++++
3 files changed, 47 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 2634a25..f593199 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -13,6 +13,8 @@

struct bpf_map;

+typedef int (*bpf_map_traverse_callback)(void *value);
+
/* map is generic key/value storage optionally accesible by eBPF programs */
struct bpf_map_ops {
/* funcs callable from userspace (via syscall) */
@@ -24,6 +26,7 @@ struct bpf_map_ops {
void *(*map_lookup_elem)(struct bpf_map *map, void *key);
int (*map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags);
int (*map_delete_elem)(struct bpf_map *map, void *key);
+ int (*map_traverse_elem)(bpf_map_traverse_callback func, struct bpf_map *map);
};

struct bpf_map {
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index cb31229..3306916 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -114,6 +114,22 @@ static int array_map_delete_elem(struct bpf_map *map, void *key)
return -EINVAL;
}

+static int array_map_traverse_elem(bpf_map_traverse_callback func, struct bpf_map *map)
+{
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
+ void *value;
+ int i;
+
+ for(i = 0; i < array->map.max_entries; i++) {
+ value = array->value + array->elem_size * i;
+
+ if (func(value) < 0)
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
static void array_map_free(struct bpf_map *map)
{
@@ -136,6 +152,7 @@ static const struct bpf_map_ops array_ops = {
.map_lookup_elem = array_map_lookup_elem,
.map_update_elem = array_map_update_elem,
.map_delete_elem = array_map_delete_elem,
+ .map_traverse_elem = array_map_traverse_elem,
};

static struct bpf_map_type_list array_type __read_mostly = {
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 83c209d..fa7887e 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -325,6 +325,32 @@ static void delete_all_elements(struct bpf_htab *htab)
}
}

+static int htab_map_traverse_elem(bpf_map_traverse_callback func, struct bpf_map *map)
+{
+ struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+ struct hlist_head *head;
+ struct htab_elem *l;
+ u32 key_size;
+ void *value;
+ int i;
+
+ key_size = map->key_size;
+
+ for (i = 0; i < htab->n_buckets; i++) {
+ head = select_bucket(htab, i);
+
+ hlist_for_each_entry_rcu(l, head, hash_node) {
+ value = l->key + round_up(key_size, 8);
+
+ if (func(value) < 0)
+ return -EINVAL;
+ }
+
+ }
+
+ return 0;
+}
+
/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
static void htab_map_free(struct bpf_map *map)
{
@@ -352,6 +378,7 @@ static const struct bpf_map_ops htab_ops = {
.map_lookup_elem = htab_map_lookup_elem,
.map_update_elem = htab_map_update_elem,
.map_delete_elem = htab_map_delete_elem,
+ .map_traverse_elem = htab_map_traverse_elem,
};

static struct bpf_map_type_list htab_type __read_mostly = {
--
1.7.10.4