tmakin/tegra-linux-noble
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

bpf: Update the struct_ops of a bpf_link.

Browse Source 
By improving the BPF_LINK_UPDATE command of bpf(), it should allow you
to conveniently switch between different struct_ops on a single
bpf_link. This would enable smoother transitions from one struct_ops
to another.

The struct_ops maps passing along with BPF_LINK_UPDATE should have the
BPF_F_LINK flag.

Signed-off-by: Kui-Feng Lee <kuifeng@meta.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230323032405.3735486-6-kuifeng@meta.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This commit is contained in:
Kui-Feng Lee
2023-03-22 20:24:02 -07:00
committed by Martin KaFai Lau
parent 8d1608d709
commit aef56f2e91
6 changed files with 122 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kernel/bpf/bpf_struct_ops.c
+47 -1
View File
@@ -65,6 +65,8 @@ struct bpf_struct_ops_link {
struct bpf_map __rcu *map;
};
static DEFINE_MUTEX(update_mutex);
#define VALUE_PREFIX "bpf_struct_ops_"
#define VALUE_PREFIX_LEN (sizeof(VALUE_PREFIX) - 1)
@@ -664,7 +666,7 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
if (attr->value_size != vt->size)
return ERR_PTR(-EINVAL);
if (attr->map_flags & BPF_F_LINK && !st_ops->validate)
if (attr->map_flags & BPF_F_LINK && (!st_ops->validate || !st_ops->update))
return ERR_PTR(-EOPNOTSUPP);
t = st_ops->type;
@@ -810,10 +812,54 @@ static int bpf_struct_ops_map_link_fill_link_info(const struct bpf_link *link,
return 0;
}
static int bpf_struct_ops_map_link_update(struct bpf_link *link, struct bpf_map *new_map,
struct bpf_map *expected_old_map)
{
struct bpf_struct_ops_map *st_map, *old_st_map;
struct bpf_map *old_map;
struct bpf_struct_ops_link *st_link;
int err = 0;
st_link = container_of(link, struct bpf_struct_ops_link, link);
st_map = container_of(new_map, struct bpf_struct_ops_map, map);
if (!bpf_struct_ops_valid_to_reg(new_map))
return -EINVAL;
mutex_lock(&update_mutex);
old_map = rcu_dereference_protected(st_link->map, lockdep_is_held(&update_mutex));
if (expected_old_map && old_map != expected_old_map) {
err = -EPERM;
goto err_out;
}
old_st_map = container_of(old_map, struct bpf_struct_ops_map, map);
/* The new and old struct_ops must be the same type. */
if (st_map->st_ops != old_st_map->st_ops) {
err = -EINVAL;
goto err_out;
}
err = st_map->st_ops->update(st_map->kvalue.data, old_st_map->kvalue.data);
if (err)
goto err_out;
bpf_map_inc(new_map);
rcu_assign_pointer(st_link->map, new_map);
bpf_map_put(old_map);
err_out:
mutex_unlock(&update_mutex);
return err;
}
static const struct bpf_link_ops bpf_struct_ops_map_lops = {
.dealloc = bpf_struct_ops_map_link_dealloc,
.show_fdinfo = bpf_struct_ops_map_link_show_fdinfo,
.fill_link_info = bpf_struct_ops_map_link_fill_link_info,
.update_map = bpf_struct_ops_map_link_update,
};
int bpf_struct_ops_link_create(union bpf_attr *attr)