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bpf: Remove migrate_{disable|enable} in ->map_for_each_callback

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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@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Hou Tao 2025-01-08 09:07:14 +08:00 committed by Alexei Starovoitov
parent 1b1a01db17
commit ea5b229630
2 changed files with 7 additions and 10 deletions
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6
kernel/bpf/arraymap.c
View File

@ -735,13 +735,13 @@ static long bpf_for_each_array_elem(struct bpf_map *map, bpf_callback_t callback
u64 ret = 0; u64 ret = 0;
void *val; void *val;
cant_migrate();
if (flags != 0) if (flags != 0)
return -EINVAL; return -EINVAL;
is_percpu = map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY; is_percpu = map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
array = container_of(map, struct bpf_array, map); array = container_of(map, struct bpf_array, map);
if (is_percpu)
migrate_disable();
for (i = 0; i < map->max_entries; i++) { for (i = 0; i < map->max_entries; i++) {
if (is_percpu) if (is_percpu)
val = this_cpu_ptr(array->pptrs[i]); 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; break;
} }
if (is_percpu)
migrate_enable();
return num_elems; return num_elems;
} }

11
kernel/bpf/hashtab.c
View File

@ -2208,17 +2208,18 @@ static long bpf_for_each_hash_elem(struct bpf_map *map, bpf_callback_t callback_
bool is_percpu; bool is_percpu;
u64 ret = 0; u64 ret = 0;
cant_migrate();
if (flags != 0) if (flags != 0)
return -EINVAL; return -EINVAL;
is_percpu = htab_is_percpu(htab); is_percpu = htab_is_percpu(htab);
roundup_key_size = round_up(map->key_size, 8); roundup_key_size = round_up(map->key_size, 8);
/* disable migration so percpu value prepared here will be the /* migration has been disabled, so percpu value prepared here will be
* same as the one seen by the bpf program with bpf_map_lookup_elem(). * 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++) { for (i = 0; i < htab->n_buckets; i++) {
b = &htab->buckets[i]; b = &htab->buckets[i];
rcu_read_lock(); rcu_read_lock();
@ -2244,8 +2245,6 @@ static long bpf_for_each_hash_elem(struct bpf_map *map, bpf_callback_t callback_
rcu_read_unlock(); rcu_read_unlock();
} }
out: out:
if (is_percpu)
migrate_enable();
return num_elems; return num_elems;
} }