Donald Hunter <donald.hunter@xxxxxxxxx> writes:
> David Vernet <void@xxxxxxxxxxxxx> writes:
>
>> On Wed, Dec 07, 2022 at 10:27:21AM +0000, Donald Hunter wrote:
>>> +
>>> +This snippet shows how to retrieve socket-local storage in a BPF program:
>>> +
>>> +.. code-block:: c
>>> +
>>> + SEC("sockops")
>>> + int _sockops(struct bpf_sock_ops *ctx)
>>> + {
>>> + struct my_storage *storage;
>>> + struct bpf_sock *sk;
>>> +
>>> + sk = ctx->sk;
>>> + if (!sk)
>>> + return 1;
>>
>> Don't feel strongly about this one, but IMO it's nice for examples to
>> illustrate code that's as close to real and pristine as possible. To
>> that point, should this example perhaps be updated to return -ENOENT
>> here, and -ENOMEM below?
>
> Will do.
>
After digging into this a bit more I notice that the sockops programs in
tools/testing/selftests/bpf/progs mostly return 1 in all cases.
I'm assuming that sockops programs should return valid values for
some op types such as BPF_SOCK_OPS_TIMEOUT_INIT. Other than that I can't
find a definitive list. Do you know if valid return values are
enumerated anywhere, or do I need to dig some more?
>>> +
>>> + storage = bpf_sk_storage_get(&socket_storage, sk, 0,
>>> + BPF_LOCAL_STORAGE_GET_F_CREATE);
>>> + if (!storage)
>>> + return 1;
>>> +
>>> + /* Use 'storage' here */
>>
>> Let's return 0 at the end to make the example program technically
>> correct.
>
> Will do.
>
>>> + }
>>
>> Thanks,
>> David
