From: Hou Tao <houtao1@xxxxxxxxxx>
BPF program may call bpf_for_each_map_elem(), and it will call
the ->map_for_each_callback callback of related bpf map. Considering the
running context of bpf program has already disabled migration, remove
the unnecessary migrate_{disable|enable} pair in the implementations of
->map_for_each_callback. To ensure the guarantee will not be voilated
later, also add cant_migrate() check in the implementations.
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
kernel/bpf/arraymap.c | 6 ++----
kernel/bpf/hashtab.c | 11 +++++------
2 files changed, 7 insertions(+), 10 deletions(-)
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 6cdbb4c33d31d..eb28c0f219ee4 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -735,13 +735,13 @@ static long bpf_for_each_array_elem(struct bpf_map *map, bpf_callback_t callback
u64 ret = 0;
void *val;
+ cant_migrate();
+
if (flags != 0)
return -EINVAL;
is_percpu = map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
array = container_of(map, struct bpf_array, map);
- if (is_percpu)
- migrate_disable();
for (i = 0; i < map->max_entries; i++) {
if (is_percpu)
val = this_cpu_ptr(array->pptrs[i]);
@@ -756,8 +756,6 @@ static long bpf_for_each_array_elem(struct bpf_map *map, bpf_callback_t callback
break;
}
- if (is_percpu)
- migrate_enable();
return num_elems;
}
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 8e2775848e0dc..3c1122281d986 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -2230,17 +2230,18 @@ static long bpf_for_each_hash_elem(struct bpf_map *map, bpf_callback_t callback_
bool is_percpu;
u64 ret = 0;
+ cant_migrate();
+
if (flags != 0)
return -EINVAL;
is_percpu = htab_is_percpu(htab);
roundup_key_size = round_up(map->key_size, 8);
- /* disable migration so percpu value prepared here will be the
- * same as the one seen by the bpf program with bpf_map_lookup_elem().
+ /* migration has been disabled, so percpu value prepared here will be
+ * the same as the one seen by the bpf program with
+ * bpf_map_lookup_elem().
*/
- if (is_percpu)
- migrate_disable();
for (i = 0; i < htab->n_buckets; i++) {
b = &htab->buckets[i];
rcu_read_lock();
@@ -2266,8 +2267,6 @@ static long bpf_for_each_hash_elem(struct bpf_map *map, bpf_callback_t callback_
rcu_read_unlock();
}
out:
- if (is_percpu)
- migrate_enable();
return num_elems;
}
--
2.29.2
