From: Hou Tao <houtao1@xxxxxxxxxx>
When freeing the array map, the destroy procedure may invoke
bpf_obj_free_fields() to free the special fields in map value
(e.g., kptr). Since kptrs may be allocated from bpf memory allocator,
migrate_{disable|enable} pairs are necessary for the freeing of these
kptrs.
To simplify reasoning about when migrate_disable() is needed for the
freeing of these dynamically-allocated kptrs, let the caller to
guarantee migration is disabled before invoking bpf_obj_free_fields().
Therefore, the patch adds migrate_{disable|enable} pair in
array_map_free(). The migrate_{disable|enable} pairs in the underlying
implementation of bpf_obj_free_fields() will be removed by the following
patch.
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
kernel/bpf/arraymap.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index eb28c0f219ee..451737493b17 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -455,6 +455,7 @@ static void array_map_free(struct bpf_map *map)
struct bpf_array *array = container_of(map, struct bpf_array, map);
int i;
+ migrate_disable();
if (!IS_ERR_OR_NULL(map->record)) {
if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {
for (i = 0; i < array->map.max_entries; i++) {
@@ -471,6 +472,7 @@ static void array_map_free(struct bpf_map *map)
bpf_obj_free_fields(map->record, array_map_elem_ptr(array, i));
}
}
+ migrate_enable();
if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
bpf_array_free_percpu(array);
--
2.29.2
