Re: [PATCH bpf-next v6 1/5] bpf: Add bpf_link support for sk_msg and sk_skb progs

[Eduard Zingerman <eddyz87@gmail.com>]

On Mon, 2024-04-08 at 08:24 -0700, Yonghong Song wrote:

[...]


> +/* Handle the following two cases:
> + * case 1: link != NULL, prog != NULL, old != NULL
> + * case 2: link != NULL, prog != NULL, old == NULL
> + */
> +static int sock_map_link_update_prog(struct bpf_link *link,
> +				     struct bpf_prog *prog,
> +				     struct bpf_prog *old)
> +{
> +	const struct sockmap_link *sockmap_link = container_of(link, struct sockmap_link, link);
> +	struct bpf_prog **pprog, *old_link_prog;
> +	struct bpf_link **plink;
> +	int ret = 0;
> +
> +	mutex_lock(&sockmap_mutex);
> +
> +	/* If old prog is not NULL, ensure old prog is the same as link->prog. */
> +	if (old && link->prog != old) {
> +		ret = -EPERM;
> +		goto out;
> +	}
> +	/* Ensure link->prog has the same type/attach_type as the new prog. */
> +	if (link->prog->type != prog->type ||
> +	    link->prog->expected_attach_type != prog->expected_attach_type) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	ret = sock_map_prog_link_lookup(sockmap_link->map, &pprog, &plink,
> +					sockmap_link->attach_type);
> +	if (ret)
> +		goto out;
> +
> +	/* return error if the stored bpf_link does not match the incoming bpf_link. */
> +	if (link != *plink)
> +		return -EBUSY;

Hi Yonghong,

Sorry, this was a mistake on my side,
this needs a 'goto out' in order to unlock the mutex.

Thanks,
Eduard

> +
> +	if (old) {
> +		ret = psock_replace_prog(pprog, prog, old);
> +		if (ret)
> +			goto out;
> +	} else {
> +		psock_set_prog(pprog, prog);
> +	}
> +
> +	bpf_prog_inc(prog);
> +	old_link_prog = xchg(&link->prog, prog);
> +	bpf_prog_put(old_link_prog);
> +
> +out:
> +	mutex_unlock(&sockmap_mutex);
> +	return ret;
> +}