On Fri, Sep 22, 2023 at 08:24:24AM +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 <avkras...@salutedevices.com>
---
Changelog:
v5(big patchset) -> v1:
 * Compact 'if' conditions.
 * Rename 'zc_val' to 'zerocopy'.
 * Use 'zerocopy' value directly in 'sock_valbool_flag()', without
   ?: operator.
 * Set 'SOCK_CUSTOM_SOCKOPT' bit for connectible sockets only, as
   suggested by Bobby Eshleman <bobbyeshle...@gmail.com>.

net/vmw_vsock/af_vsock.c | 46 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 44 insertions(+), 2 deletions(-)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 482300eb88e0..c05a42e02a17 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 +1674,34 @@ 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);

it's not necessary to wrap this call.

+               goto exit;
+       }
+
        switch (optname) {
        case SO_VM_SOCKETS_BUFFER_SIZE:
                COPY_IN(val);
@@ -2322,6 +2358,12 @@ 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


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