Re: [PATCH bpf-next 4/6] selftests/bpf: Add setsockopt for network_helper_opts

[Martin KaFai Lau <martin.lau@linux.dev>]

On 4/24/24 8:23 PM, Geliang Tang wrote:
> +static int setsockopt_reuseport(int fd, const void *optval, socklen_t optlen)
> +{
> +	return setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, optval, optlen);
>   }
>   

[ ... ]

>   void free_fds(int *fds, unsigned int nr_close_fds)
> diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h
> index c62b54daa914..540ecfc52bd7 100644
> --- a/tools/testing/selftests/bpf/network_helpers.h
> +++ b/tools/testing/selftests/bpf/network_helpers.h
> @@ -28,6 +28,9 @@ struct network_helper_opts {
>   	bool noconnect;
>   	int type;
>   	int proto;
> +	int (*setsockopt)(int fd, const void *optval, socklen_t optlen);
> +	const void *optval;
> +	socklen_t optlen;

optval and optlen could be in the stack of the (*setsockopt) callback.
e.g. the "int on;" could be local to the setsockopt_reuseport() instead of 
adding optval/len to the network_helper_opts. Passing one optval in 
network_helper_opts could be less flexible when we want to do multiple 
setsockopt() after socket().

Another nit I would like to make, rename this from (*setsockopt) to 
(*post_socket_cb) because this callback could do more than setsockopt, e.g. 
adding a sk local storage to a socket fd before bind(). Also, add a "const 
struct post_socket_opts *opts" for future extension, Like:

struct post_socket_opts {};

int (*post_socket_cb)(int fd, const struct post_socket_opts *opts);

Patch 6 will need two setsockopt cb functions because of different optval but I 
believe the tradeoff is worth it for this callback doing more than just one 
setsockopt.

Patch 1 to 3 have been applied. Thanks.