On Wed, 7 Jun 2023 21:26:20 +0200 Daniel Borkmann wrote:
> + dev = dev_get_by_index(net, attr->link_create.target_ifindex);
> + if (!dev)
> + return -EINVAL;
> + link = kzalloc(sizeof(*link), GFP_USER);
> + if (!link) {
> + err = -ENOMEM;
> + goto out_put;
> + }
> +
> + bpf_link_init(&link->link, BPF_LINK_TYPE_TCX, &tcx_link_lops, prog);
> + link->location = attr->link_create.attach_type;
> + link->flags = attr->link_create.flags & (BPF_F_FIRST | BPF_F_LAST);
> + link->dev = dev;
> +
> + err = bpf_link_prime(&link->link, &link_primer);
> + if (err) {
> + kfree(link);
> + goto out_put;
> + }
> + rtnl_lock();
How does this work vs device unregistering?
Best I can tell (and it is a large patch :() the device may have passed
dev_tcx_uninstall() by the time we take the lock.
> + err = tcx_link_prog_attach(&link->link, attr->link_create.flags,
> + attr->link_create.tcx.relative_fd,
> + attr->link_create.tcx.expected_revision);
> + if (!err)
> + fd = bpf_link_settle(&link_primer);
> + rtnl_unlock();
