code stopping and lua_sethook

[Arithmeth <arithmeth@...>]

Hello everybody,

I'd like to use Lua inside  my C program, and I'd like to know what I can do with Lua and what is the better approach to my problem. I hope someone on the list might help.

I want to open a file, and execute a function from there. The function does some lua stuff and eventually calls some C function which interact with custom hardware. Easy, till now.
Problems arise when I want to stop the execution of the function in response to some signal from the hardware.
I've read I can safely stop Lua code execution only using lua_sethook. 
But, what I also want to do is to execute another lua function, and then go back to the previous one. It actually works.
Here is what I do:
In the hook function, I generate a new thread with lua_newthread and resume it. I can modify globals variables in the lua scripts, call C function, and also stop the previuosly running function, if needed. Otherwise, I can go back to continue with execution of the previous function.
An example lua script could be:
----------------------------
function first ()
{

    while (1) do a=a+1 end
}

function second ()
{
    while (1) do end
}


----------------------------

What I can't do is nesting calls. While the interrupting function is running, I can't stop it to call another function, then go back to the previous call, then back to the first function. From lua manual (
http://www.lua.org/manual/5.1/manual.html#lua_Hook):
While Lua is running a hook, it disables other calls to hooks.
Therefore, if a hook calls back Lua to execute a function or a chunk,
this execution occurs without any calls to hooks."

I believe using a debug function (lua_sethook) is not the correct approach to the problem. And I only solved part of the problem (I can make just one nesting). But I'd like to know what could the correct approach to the problem.

Any ideas?

All my regards,

Arithmeth