VSOCK: defer sock removal to transports

The virtio transport will implement graceful shutdown and the related
SO_LINGER socket option.  This requires orphaning the sock but keeping
it in the table of connections after .release().

This patch adds the vsock_remove_sock() function and leaves it up to the
transport when to remove the sock.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

include/net/af_vsock.h

@@ -180,6 +180,7 @@ void vsock_remove_connected(struct vsock_sock *vsk);
 struct sock *vsock_find_bound_socket(struct sockaddr_vm *addr);
 struct sock *vsock_find_connected_socket(struct sockaddr_vm *src,
 					 struct sockaddr_vm *dst);
+void vsock_remove_sock(struct vsock_sock *vsk);
 void vsock_for_each_connected_socket(void (*fn)(struct sock *sk));
 
 #endif /* __AF_VSOCK_H__ */

net/vmw_vsock/af_vsock.c

@@ -344,6 +344,16 @@ static bool vsock_in_connected_table(struct vsock_sock *vsk)
 	return ret;
 }
 
+void vsock_remove_sock(struct vsock_sock *vsk)
+{
+	if (vsock_in_bound_table(vsk))
+		vsock_remove_bound(vsk);
+
+	if (vsock_in_connected_table(vsk))
+		vsock_remove_connected(vsk);
+}
+EXPORT_SYMBOL_GPL(vsock_remove_sock);
+
 void vsock_for_each_connected_socket(void (*fn)(struct sock *sk))
 {
 	int i;
@@ -660,12 +670,6 @@ static void __vsock_release(struct sock *sk)
 		vsk = vsock_sk(sk);
 		pending = NULL;	/* Compiler warning. */
 
-		if (vsock_in_bound_table(vsk))
-			vsock_remove_bound(vsk);
-
-		if (vsock_in_connected_table(vsk))
-			vsock_remove_connected(vsk);
-
 		transport->release(vsk);
 
 		lock_sock(sk);

net/vmw_vsock/vmci_transport.c

@@ -1644,6 +1644,8 @@ static void vmci_transport_destruct(struct vsock_sock *vsk)
 
 static void vmci_transport_release(struct vsock_sock *vsk)
 {
+	vsock_remove_sock(vsk);
+
 	if (!vmci_handle_is_invalid(vmci_trans(vsk)->dg_handle)) {
 		vmci_datagram_destroy_handle(vmci_trans(vsk)->dg_handle);
 		vmci_trans(vsk)->dg_handle = VMCI_INVALID_HANDLE;