RE: [PATCH net-next 3/6] vsock: add local transport support in the vsock core

Jorgen Hansen
2019-11-21T15:04:25Z

> From: Stefano Garzarella [mailto:sgarzare@redhat.com]
> Sent: Tuesday, November 19, 2019 12:01 PM
> To: netdev@vger.kernel.org
>
> This patch allows to register a transport able to handle
> local communication (loopback).
>
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
> include/net/af_vsock.h | 2 ++
> net/vmw_vsock/af_vsock.c | 17 ++++++++++++++++-
> 2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
> index 4206dc6d813f..b1c717286993 100644
> --- a/include/net/af_vsock.h
> +++ b/include/net/af_vsock.h
> @@ -98,6 +98,8 @@ struct vsock_transport_send_notify_data {
> #define VSOCK_TRANSPORT_F_G2H 0x00000002
> /* Transport provides DGRAM communication */
> #define VSOCK_TRANSPORT_F_DGRAM 0x00000004
> +/* Transport provides local (loopback) communication */
> +#define VSOCK_TRANSPORT_F_LOCAL 0x00000008
>
> struct vsock_transport {
> struct module *module;
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index cc8659838bf2..c9e5bad59dc1 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -136,6 +136,8 @@ static const struct vsock_transport *transport_h2g;
> static const struct vsock_transport *transport_g2h;
> /* Transport used for DGRAM communication */
> static const struct vsock_transport *transport_dgram;
> +/* Transport used for local communication */
> +static const struct vsock_transport *transport_local;
> static DEFINE_MUTEX(vsock_register_mutex);
>
> /**** UTILS ****/
> @@ -2130,7 +2132,7 @@ EXPORT_SYMBOL_GPL(vsock_core_get_transport);
>
> int vsock_core_register(const struct vsock_transport *t, int features)
> {
> - const struct vsock_transport *t_h2g, *t_g2h, *t_dgram;
> + const struct vsock_transport *t_h2g, *t_g2h, *t_dgram, *t_local;
> int err = mutex_lock_interruptible(&vsock_register_mutex);
>
> if (err)
> @@ -2139,6 +2141,7 @@ int vsock_core_register(const struct
> vsock_transport *t, int features)
> t_h2g = transport_h2g;
> t_g2h = transport_g2h;
> t_dgram = transport_dgram;
> + t_local = transport_local;
>
> if (features & VSOCK_TRANSPORT_F_H2G) {
> if (t_h2g) {
> @@ -2164,9 +2167,18 @@ int vsock_core_register(const struct
> vsock_transport *t, int features)
> t_dgram = t;
> }
>
> + if (features & VSOCK_TRANSPORT_F_LOCAL) {
> + if (t_local) {
> + err = -EBUSY;
> + goto err_busy;
> + }
> + t_local = t;
> + }
> +
> transport_h2g = t_h2g;
> transport_g2h = t_g2h;
> transport_dgram = t_dgram;
> + transport_local = t_local;
>
> err_busy:
> mutex_unlock(&vsock_register_mutex);
> @@ -2187,6 +2199,9 @@ void vsock_core_unregister(const struct
> vsock_transport *t)
> if (transport_dgram == t)
> transport_dgram = NULL;
>
> + if (transport_local == t)
> + transport_local = NULL;
> +
> mutex_unlock(&vsock_register_mutex);
> }
> EXPORT_SYMBOL_GPL(vsock_core_unregister);
> --
> 2.21.0

Having loopback support as a separate transport fits nicely, but do we need to support
different variants of loopback? It could just be built in.

Thanks,
Jorgen