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

[Stefano Garzarella]

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.deme...@gmail.com>
Signed-off-by: Luigi Leonardi <luigi.leona...@outlook.com>
---
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