Re: [PATCH net-next v2 08/12] vsock: enable setting SO_ZEROCOPY

From: Stefano Garzarella
Date: Tue Oct 03 2023 - 12:24:29 EST


On Sun, Oct 01, 2023 at 12:03:04AM +0300, Arseniy Krasnov wrote:
For AF_VSOCK, zerocopy tx mode depends on transport, so this option must
be set in AF_VSOCK implementation where transport is accessible (if
transport is not set during setting SO_ZEROCOPY: for example socket is
not connected, then SO_ZEROCOPY will be enabled, but once transport will
be assigned, support of this type of transmission will be checked).

To handle SO_ZEROCOPY, AF_VSOCK implementation uses SOCK_CUSTOM_SOCKOPT
bit, thus handling SOL_SOCKET option operations, but all of them except
SO_ZEROCOPY will be forwarded to the generic handler by calling
'sock_setsockopt()'.

Signed-off-by: Arseniy Krasnov <avkrasnov@xxxxxxxxxxxxxxxxx>
---
Changelog:
v1 -> v2:
* Place 'sock_valbool_flag()' in a single line.

net/vmw_vsock/af_vsock.c | 45 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 43 insertions(+), 2 deletions(-)

Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>


diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index ff44bab05191..a84f242466cf 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1406,8 +1406,16 @@ static int vsock_connect(struct socket *sock, struct sockaddr *addr,
goto out;
}

- if (vsock_msgzerocopy_allow(transport))
+ if (vsock_msgzerocopy_allow(transport)) {
set_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags);
+ } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
+ /* If this option was set before 'connect()',
+ * when transport was unknown, check that this
+ * feature is supported here.
+ */
+ err = -EOPNOTSUPP;
+ goto out;
+ }

err = vsock_auto_bind(vsk);
if (err)
@@ -1643,7 +1651,7 @@ static int vsock_connectible_setsockopt(struct socket *sock,
const struct vsock_transport *transport;
u64 val;

- if (level != AF_VSOCK)
+ if (level != AF_VSOCK && level != SOL_SOCKET)
return -ENOPROTOOPT;

#define COPY_IN(_v) \
@@ -1666,6 +1674,33 @@ static int vsock_connectible_setsockopt(struct socket *sock,

transport = vsk->transport;

+ if (level == SOL_SOCKET) {
+ int zerocopy;
+
+ if (optname != SO_ZEROCOPY) {
+ release_sock(sk);
+ return sock_setsockopt(sock, level, optname, optval, optlen);
+ }
+
+ /* Use 'int' type here, because variable to
+ * set this option usually has this type.
+ */
+ COPY_IN(zerocopy);
+
+ if (zerocopy < 0 || zerocopy > 1) {
+ err = -EINVAL;
+ goto exit;
+ }
+
+ if (transport && !vsock_msgzerocopy_allow(transport)) {
+ err = -EOPNOTSUPP;
+ goto exit;
+ }
+
+ sock_valbool_flag(sk, SOCK_ZEROCOPY, zerocopy);
+ goto exit;
+ }
+
switch (optname) {
case SO_VM_SOCKETS_BUFFER_SIZE:
COPY_IN(val);
@@ -2322,6 +2357,12 @@ static int vsock_create(struct net *net, struct socket *sock,
}
}

+ /* SOCK_DGRAM doesn't have 'setsockopt' callback set in its
+ * proto_ops, so there is no handler for custom logic.
+ */
+ if (sock_type_connectible(sock->type))
+ set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags);
+
vsock_insert_unbound(vsk);

return 0;
--
2.25.1