This is needed for the next patches that change the way the security calls work.

Linus, please apply.  This defines wait_task_inactive() to be a no-op
on UP machines, and removes the #ifdef CONFIG_SMP which surrounds
current calls.

This also fixes compile on UP which was broken by the addition of a
call to wait_task_inactive in fs/exec.c which was not protected by an
#ifdef.

This contains Daniel's suggested fix that allows a parent to
PTRACE_ATTACH to a child it forked.  That fixes the incorrect BUG_ON()
assert that Ogawa's patch was intended to fix, and we thus undo Ogawa's
patch.

I've tested various ptrace uses and they appear to work just fine.

the attached patch updates a number of items:

 - adds cleanups suggested by Christoph Hellwig: needed unlikely()
   statements, a superfluous #define and line length problems.

 - splits up the global ptrace list into per-task ptrace lists. This was
   pretty straightforward, and this makes the worst-case exit() latency
   O(nr_children).

the per-task ptrace lists unearthed a bug that the previous code did not
take care of: tasks on the ptrace list have to be correctly reparented as
well. This patch passed my stresstests as well.

Audit put_page() uses of pages that may be in the page cache.

Use page_cache_release() instead.

in the page cache, it needs to use page_cache_release()
instead of plain "put_page()".

The patch below consolidates some duplicate code, reduces some
indentation, and adds a freeing of a page in mem_read() that could be left
unfreed, as far as I can see.

We weren't incrementing the address when walking a processes
address space.  From 2.4

This patch (#1) just converts the task_struct to use struct list_head rather
than direct pointers for maintaining the children list.

The patch below changes access_process_vm to use a new architecture
hook, flush_icache_user_range, instead of flush_icache_page, and adds
a definition of flush_icache_user_range which does the same thing as
flush_icache_page for all architectures except PPC.  (The PPC update
that is in Linus' BK tree already includes a suitable definition of
flush_icache_user_range.)

The reason for doing this is that when flush_icache_page is called
from do_no_page or do_swap_page, I want to be able to do the flush
conditionally, based on the state of the page.  In contrast,
access_process_vm needs to do the flush unconditionally since it has
just modified the page.  In the access_process_vm case it is useful to
have the information about the user address and length that have been
modified since then we can just flush the affected cache lines rather
than the whole page.

This patch should make it easy to improve performance on alpha, since
there (as I understand it) the icache flush is not needed at all in
do_no_page or do_swap_page, but is needed in access_process_vm.  All
that is needed is to make flush_icache_page a noop on alpha.  The
patch below doesn't do this, I'll let the alpha maintainers push that
change if they want.

- Kai Germaschewski: ISDN updates
- Al Viro: start moving buffer cache indexing to "struct block_device *"
- Greg KH: USB update
- Russell King: fix up some ARM merge issues
- Ingo Molnar: scalable scheduler

- Jens Axboe: more bio updates, fix some request list bogosity under load
- Al Viro: export seq_xxx functions
- Manfred Spraul: include file cleanups, pc110pad compile fix
- David Woodhouse: fix JFFS2 write error handling
- Dave Jones: start merging up with 2.4.x patches
- Manfred Spraul: coredump fixes, FS event counter cleanups
- me: fix SCSI CD-ROM sectorsize BIO breakage

  - David Brownell: usbnet update
  - Greg KH: USB and PCI hotplug update
  - Ingo/me: fix SCHED_FIFO for UP/SMP for good (flw).
  - Add back direct_IO now that it works again.

  - Alan Cox: much more merging
  - Pete Zaitcev: ymfpci race fixes
  - Andrea Arkangeli: VM race fix and OOM tweak.
  - Arjan Van de Ven: merge RH kernel fixes
  - Andi Kleen: use more readable 'likely()/unlikely()' instead of __builtin_expect()
  - Keith Owens: fix 64-bit ELF types
  - Gerd Knorr: mark more broken PCI bridges, update btaudio driver
  - Paul Mackerras: powermac driver update
  - me: clean up PTRACE_DETACH to use common infrastructure

  - me: fix ptrace and /proc issues with new core-dump permissions
  - numerous: IDE tape driver update for completion handlers
  - Ben Collins: ieee1394 GUID cleanups
  - Jacek Stepniewski: nasty deadlock in rename()

  - Rik van Riel and others: mm rw-semaphore (ps/top ok when swapping)
  - IDE: 256 sectors at a time is legal, but apparently confuses some
  drives. Max out at 255 sectors instead.
  - Petko Manolov: USB pegasus driver update
  - make the boottime memory map printout at least almost readable.
  - USB driver updates
  - pte_alloc()/pmd_alloc() need page_table_lock.

  - Petr Vandrovec, Al Viro: dentry revalidation fixes
  - Stephen Tweedie / Manfred Spraul: kswapd and ptrace race
  - Neil Brown: nfsd/rpc/raid cleanups and fixes