I found 4 minor problems in the thread creation code:

* 2.2 reserved 4 threads for root, and 2.4 still has the
define (MIN_THREADS_LEFT_FOR_ROOT), but the code is missing :-(

* get_pid causes a deadlock when all pid numbers are in use.
In the worst case, only 10900 threads are required to exhaust
the 15 bit pid space.

* in theory, fork_init() might give 2 tasks the same pid, although
this can only happen when all but 1 or 2 pids are in use:

<<
fork_init() runs with the BKL acquired.
It first calls get_pid(), and get_pid() internally scans
	the task queue and returns a pid number that
	is not used by a thread on the task queue.
	But it doesn't add the thread to the task queue.

copy_xy() can sleep, thus the BKL is released.

At the end of fork_init(), the new task is added to the task queue.

--> if 2 thread are within fork_init(), then both might get the
same pid!
>>>

* the spinlock within get_pid is bogus: get_pid isn't SMP safe.

I've attached a patch (tested with 2.4.0-test12).


--
  Manfred