Do Kernel timer handlers execute on individual threads?

Hello,
I've been working on a network device driver for kernel 2.6.27. In this driver, I have setup a timer to execute my handler function every 20ms. I was wondering if my handler function will execute in its own kenel thread or not?
I guess the core of the question is whether or not the kernel code which invokes a the timeout handler function, starts the function in a new kernel thread or not?

Thanks for your help.

Timer handlers are executes as soft interrupts, i.e., not in a thread; they cannot sleep.

If you dont mind could you show the code you use to execute your function?

Thanks.