Commit fa5e83df authored by Yafang Shao's avatar Yafang Shao Committed by Alexei Starovoitov
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bpf: devmap memory usage 



A new helper is introduced to calculate the memory usage of devmap and
devmap_hash. The number of dynamically allocated elements are recored
for devmap_hash already, but not for devmap. To track the memory size of
dynamically allocated elements, this patch also count the numbers for
devmap.

The result as follows,
- before
40: devmap  name count_map  flags 0x80
        key 4B  value 4B  max_entries 65536  memlock 524288B
41: devmap_hash  name count_map  flags 0x80
        key 4B  value 4B  max_entries 65536  memlock 524288B

- after
40: devmap  name count_map  flags 0x80  <<<< no elements
        key 4B  value 4B  max_entries 65536  memlock 524608B
41: devmap_hash  name count_map  flags 0x80 <<<< no elements
        key 4B  value 4B  max_entries 65536  memlock 524608B

Note that the number of buckets is same with max_entries for devmap_hash
in this case.

Signed-off-by: default avatarYafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230305124615.12358-11-laoar.shao@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 835f1fca

kernel/bpf/devmap.c

+24 −2
Original line number Diff line number Diff line
@@ -819,8 +819,10 @@ static int dev_map_delete_elem(struct bpf_map *map, void *key) 
		return -EINVAL;



	old_dev = unrcu_pointer(xchg(&dtab->netdev_map[k], NULL));

	if (old_dev)

	if (old_dev) {

		call_rcu(&old_dev->rcu, __dev_map_entry_free);

		atomic_dec((atomic_t *)&dtab->items);

	}

	return 0;

}
@@ -931,6 +933,8 @@ static int __dev_map_update_elem(struct net *net, struct bpf_map *map, 
	old_dev = unrcu_pointer(xchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev)));

	if (old_dev)

		call_rcu(&old_dev->rcu, __dev_map_entry_free);

	else

		atomic_inc((atomic_t *)&dtab->items);



	return 0;

}
@@ -1016,6 +1020,20 @@ static int dev_hash_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags) 
				      __dev_map_hash_lookup_elem);

}



static u64 dev_map_mem_usage(const struct bpf_map *map)

{

	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);

	u64 usage = sizeof(struct bpf_dtab);



	if (map->map_type == BPF_MAP_TYPE_DEVMAP_HASH)

		usage += (u64)dtab->n_buckets * sizeof(struct hlist_head);

	else

		usage += (u64)map->max_entries * sizeof(struct bpf_dtab_netdev *);

	usage += atomic_read((atomic_t *)&dtab->items) *

			 (u64)sizeof(struct bpf_dtab_netdev);

	return usage;

}



BTF_ID_LIST_SINGLE(dev_map_btf_ids, struct, bpf_dtab)

const struct bpf_map_ops dev_map_ops = {

	.map_meta_equal = bpf_map_meta_equal,
@@ -1026,6 +1044,7 @@ const struct bpf_map_ops dev_map_ops = { 
	.map_update_elem = dev_map_update_elem,

	.map_delete_elem = dev_map_delete_elem,

	.map_check_btf = map_check_no_btf,

	.map_mem_usage = dev_map_mem_usage,

	.map_btf_id = &dev_map_btf_ids[0],

	.map_redirect = dev_map_redirect,

};
@@ -1039,6 +1058,7 @@ const struct bpf_map_ops dev_map_hash_ops = { 
	.map_update_elem = dev_map_hash_update_elem,

	.map_delete_elem = dev_map_hash_delete_elem,

	.map_check_btf = map_check_no_btf,

	.map_mem_usage = dev_map_mem_usage,

	.map_btf_id = &dev_map_btf_ids[0],

	.map_redirect = dev_hash_map_redirect,

};
@@ -1109,9 +1129,11 @@ static int dev_map_notification(struct notifier_block *notifier, 
				if (!dev || netdev != dev->dev)

					continue;

				odev = unrcu_pointer(cmpxchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev), NULL));

				if (dev == odev)

				if (dev == odev) {

					call_rcu(&dev->rcu,

						 __dev_map_entry_free);

					atomic_dec((atomic_t *)&dtab->items);

				}

			}

		}

		rcu_read_unlock();