Re: [PATCH net-next v2 1/3] vsock: add support for SIOCOUTQ ioctl for all vsock socket types.

[Stefano Garzarella <sgarzare@xxxxxxxxxx>]

On Mon, Apr 08, 2024 at 03:37:47PM GMT, Luigi Leonardi wrote:
> This add support for ioctl(s) for SOCK_STREAM SOCK_SEQPACKET and SOCK_DGRAM
> in AF_VSOCK.
> The only ioctl available is SIOCOUTQ/TIOCOUTQ, which returns the number
> of unsent bytes in the socket. This information is transport-specific
> and is delegated to them using a callback.
>
> Suggested-by: Daan De Meyer <daan.j.demeyer@xxxxxxxxx>
> Signed-off-by: Luigi Leonardi <luigi.leonardi@xxxxxxxxxxx>
> ---
> include/net/af_vsock.h   |  3 +++
> net/vmw_vsock/af_vsock.c | 51 +++++++++++++++++++++++++++++++++++++---
> 2 files changed, 51 insertions(+), 3 deletions(-)
>
> diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
> index 535701efc1e5..7d67faa7bbdb 100644
> --- a/include/net/af_vsock.h
> +++ b/include/net/af_vsock.h
> @@ -169,6 +169,9 @@ struct vsock_transport {
> 	void (*notify_buffer_size)(struct vsock_sock *, u64 *);
> 	int (*notify_set_rcvlowat)(struct vsock_sock *vsk, int val);
>
> +	/* SIOCOUTQ ioctl */
> +	int (*unsent_bytes)(struct vsock_sock *vsk);
> +
> 	/* Shutdown. */
> 	int (*shutdown)(struct vsock_sock *, int);
>
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index 54ba7316f808..fc108283409a 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -112,6 +112,7 @@
> #include <net/sock.h>
> #include <net/af_vsock.h>
> #include <uapi/linux/vm_sockets.h>
> +#include <uapi/asm-generic/ioctls.h>
>
> static int __vsock_bind(struct sock *sk, struct sockaddr_vm *addr);
> static void vsock_sk_destruct(struct sock *sk);
> @@ -1292,6 +1293,50 @@ int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
> }
> EXPORT_SYMBOL_GPL(vsock_dgram_recvmsg);
>
> +static int vsock_do_ioctl(struct socket *sock, unsigned int cmd,
> +			  int __user *arg)
> +{
> +	struct sock *sk = sock->sk;
> +	struct vsock_sock *vsk;
> +	int retval;
> +
> +	vsk = vsock_sk(sk);
> +
> +	switch (cmd) {
> +	case SIOCOUTQ: {
> +		int n_bytes;
> +
> +		if (vsk->transport->unsent_bytes) {

Should we also check the `vsk->transport` is not null?

I also suggest an early return, or to have the shortest branch on top
for readability:

		if (!vsk->transport || !vsk->transport->unsent_bytes) {
			retval = -EOPNOTSUPP;
			break;
		}

Thanks,
Stefano

> +			if (sock_type_connectible(sk->sk_type) && sk->sk_state == TCP_LISTEN) {
> +				retval = -EINVAL;
> +				break;
> +			}
> +
> +			n_bytes = vsk->transport->unsent_bytes(vsk);
> +			if (n_bytes < 0) {
> +				retval = n_bytes;
> +				break;
> +			}
> +
> +			retval = put_user(n_bytes, arg);
> +		} else {
> +			retval = -EOPNOTSUPP;
> +		}
> +		break;
> +	}
> +	default:
> +		retval = -ENOIOCTLCMD;
> +	}
> +
> +	return retval;
> +}
> +
> +static int vsock_ioctl(struct socket *sock, unsigned int cmd,
> +		       unsigned long arg)
> +{
> +	return vsock_do_ioctl(sock, cmd, (int __user *)arg);
> +}
> +
> static const struct proto_ops vsock_dgram_ops = {
> 	.family = PF_VSOCK,
> 	.owner = THIS_MODULE,
> @@ -1302,7 +1347,7 @@ static const struct proto_ops vsock_dgram_ops = {
> 	.accept = sock_no_accept,
> 	.getname = vsock_getname,
> 	.poll = vsock_poll,
> -	.ioctl = sock_no_ioctl,
> +	.ioctl = vsock_ioctl,
> 	.listen = sock_no_listen,
> 	.shutdown = vsock_shutdown,
> 	.sendmsg = vsock_dgram_sendmsg,
> @@ -2286,7 +2331,7 @@ static const struct proto_ops vsock_stream_ops = {
> 	.accept = vsock_accept,
> 	.getname = vsock_getname,
> 	.poll = vsock_poll,
> -	.ioctl = sock_no_ioctl,
> +	.ioctl = vsock_ioctl,
> 	.listen = vsock_listen,
> 	.shutdown = vsock_shutdown,
> 	.setsockopt = vsock_connectible_setsockopt,
> @@ -2308,7 +2353,7 @@ static const struct proto_ops vsock_seqpacket_ops = {
> 	.accept = vsock_accept,
> 	.getname = vsock_getname,
> 	.poll = vsock_poll,
> -	.ioctl = sock_no_ioctl,
> +	.ioctl = vsock_ioctl,
> 	.listen = vsock_listen,
> 	.shutdown = vsock_shutdown,
> 	.setsockopt = vsock_connectible_setsockopt,
> --
> 2.34.1