On 3/9/23 09:09, Martin KaFai Lau wrote:
On 3/8/23 4:22 PM, Kui-Feng Lee wrote:
On 3/8/23 13:42, Martin KaFai Lau wrote:
On 3/7/23 4:50 PM, Kui-Feng Lee wrote:
@@ -11566,22 +11591,34 @@ struct bpf_link *bpf_program__attach(const
struct bpf_program *prog)
return link;
}
+struct bpf_link_struct_ops {
+ struct bpf_link link;
+ int map_fd;
+};
+
static int bpf_link__detach_struct_ops(struct bpf_link *link)
{
+ struct bpf_link_struct_ops *st_link;
__u32 zero = 0;
- if (bpf_map_delete_elem(link->fd, &zero))
- return -errno;
+ st_link = container_of(link, struct bpf_link_struct_ops, link);
- return 0;
+ if (st_link->map_fd < 0) {
map_fd < 0 should always be true?
If the user pass a wrong link, it can fail.
I may have missed something. How can user directly pass a link to this
static function?
Ouch! You are right. This check is not necessary. I mixed it with the
old detach feature.
I check it here explicitly even the kernel returns
an error for deleting an element of a struct_ops w/ link.
Yep, the kernel should have stopped the delete if the user somehow
corrupted the map_fd to -1.
+ /* Fake bpf_link */
+ if (bpf_map_delete_elem(link->fd, &zero))
+ return -errno;
+ return 0;
+ }
+
+ /* Doesn't support detaching. */
+ return -EOPNOTSUPP;
