[PATCH v2 2/5] bpf: Add function map->ops->map_traverse_elem() to traverse map elems

Kaixu Xia
2015-07-22T08:10:12Z

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 +++++++++++++++++
2 files changed, 20 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index f6a2442..257149c 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -15,6 +15,8 @@

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) */
@@ -26,6 +28,7 @@ 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 183c1f7..410bc40 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -276,12 +276,29 @@ static int perf_event_array_map_get_next_key(struct bpf_map *map, void *key,
return -EINVAL;
}

+static int perf_event_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;
+
+ func(value);
+ }
+
+ return 0;
+}
+
static const struct bpf_map_ops perf_event_array_ops = {
.map_alloc = perf_event_array_map_alloc,
.map_free = array_map_free,
.map_get_next_key = perf_event_array_map_get_next_key,
.map_lookup_elem = array_map_lookup_elem,
.map_delete_elem = array_map_delete_elem,
+ .map_traverse_elem = perf_event_array_map_traverse_elem,
};

static struct bpf_map_type_list perf_event_array_type __read_mostly = {
--
1.8.3.4