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

[Yonghong Song <yonghong.song@linux.dev>]

On 4/9/24 2:52 AM, Eduard Zingerman wrote:
> 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.

It is my fault as well since I missed it too. Will send a revision later today
just in case there are more comments.

>
> 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;
>> +}