are you thinking about something like this:

--8<---------------cut here---------------start------------->8---
(defun TeX-process-check (name)
  "Check if a process for the TeX document NAME already exists.
If so, give the user the choice of aborting the process or the current
command."
  (let (process)
    (while (and (setq process (TeX-process name))
                (eq (process-status process) 'run))
      (cond
       ((or TeX-kill-process-no-query ; (t or nil)
            (yes-or-no-p (concat "Process `"
                                 (process-name process)
                                 "' for document `"
                                 name
                                 "' running, kill it? ")))
        (delete-process process))
       ((eq (process-status process) 'run)
        (error "Cannot have two processes for the same document"))))))
--8<---------------cut here---------------end--------------->8---