net: Add get_vhost_net callback to NetClientInfo

The get_vhost_net() function previously contained a large switch
statement to find the VHostNetState pointer based on the net
client's type. This created a tight coupling, requiring the generic
vhost layer to be aware of every specific backend that supported
vhost, such as tap, vhost-user, and vhost-vdpa.

This approach is not scalable and requires modifying a central function
for any new backend. It also forced each backend to expose its internal
getter function in a public header file.

This patch refactors the logic by introducing a new get_vhost_net
function pointer to the NetClientInfo struct. The central
get_vhost_net() function is now a simple, generic dispatcher that
invokes the callback provided by the net client.

Each backend now implements its own private getter and registers it in
its NetClientInfo.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/vhost-user.c b/net/vhost-user.c
index 10ac8dc0b3..b7bf0d2042 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -32,7 +32,7 @@ typedef struct NetVhostUserState {
     bool started;
 } NetVhostUserState;
 
-VHostNetState *vhost_user_get_vhost_net(NetClientState *nc)
+static struct vhost_net *vhost_user_get_vhost_net(NetClientState *nc)
 {
     NetVhostUserState *s = DO_UPCAST(NetVhostUserState, nc, nc);
     assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_USER);
@@ -231,6 +231,7 @@ static NetClientInfo net_vhost_user_info = {
         .set_vnet_be = vhost_user_set_vnet_endianness,
         .set_vnet_le = vhost_user_set_vnet_endianness,
         .check_peer_type = vhost_user_check_peer_type,
+        .get_vhost_net = vhost_user_get_vhost_net,
 };
 
 static gboolean net_vhost_user_watch(void *do_not_use, GIOCondition cond,