How to check if linked server is running within a function?

Question

I know that there is a way to check if the linked server is running.
I wanna know if there is a way to check it inside a function I wrote this code:

  create function dbo.Ck_DB_Stat
(@servername nvarchar (20))
returns bit
AS
BEGIN

    declare @srvr nvarchar(128), @retval int, @res nvarchar (10)

    declare @ck bit
    set @srvr = @servername;
    begin try
        exec @retval = sys.sp_testlinkedserver @srvr;
        set @ck = 1
    end try

    begin catch
        set @retval = sign(@@error);
    end catch;

    if @retval <> 0
        set @ck = 0
    return @ck
END