This is the next iteration of the workqueue abstraction.

The framework includes:

 - per-CPU queueing support.

on SMP there is a per-CPU worker thread (bound to its CPU) and per-CPU
work queues - this feature is completely transparent to workqueue-users.
keventd automatically uses this feature. XFS can now update to work-queues
and have the same per-CPU performance as it had with its per-CPU worker
threads.

 - delayed work submission

there's a new queue_delayed_work(wq, work, delay) function and a new
schedule_delayed_work(work, delay) function. The later one is used to
correctly fix former tq_timer users. I've reverted those changes in 2.5.40
that changed tq_timer uses to schedule_work() - eg. in the case of
random.c or the tty flip queue it was definitely the wrong thing to do.

delayed work means a timer embedded in struct work_struct.  I considered
using split struct work_struct and delayed_work_struct types, but lots
of code actively uses task-queues in both delayed and non-delayed mode,
so i went for the more generic approach that allows both methods of work
submission.  Delayed timers do not cause any other overhead in the
normal submission path otherwise.

 - multithreaded run_workqueue() implementation

the run_workqueue() function can now be called from multiple contexts, and
a worker thread will only use up a single entryy - this property is used
by the flushing code, and can potentially be used in the future to extend
the number of per-CPU worker threads.

 - more reliable flushing

there's now a 'pending work' counter, which is used to accurately detect
when the last work-function has finished execution. It's also used to
correctly flush against timed requests. I'm not convinced whether the old
keventd implementation got this detail right.

 - i switched the arguments of the queueing function(s) per Jeff's
   suggestion, it's more straightforward this way.


Driver fixes:

i have converted almost every affected driver to the new framework. This
cleaned up tons of code. I also fixed a number of drivers that were still
using BHs (these drivers did not compile in 2.5.40).

while this means lots of changes, it might ease the QA decision whether to
put this patch into 2.5.

The pach converts roughly 80% of all tqueue-using code to workqueues - and
all the places that are not converted to workqueues yet are places that do
not compile in vanilla 2.5.40 anyway, due to unrelated changes. I've
converted a fair number of drivers that do not compile in 2.5.40, and i
think i've managed to convert every driver that compiles under 2.5.40.

This patch removes the concept of "logical" CPU numbers, in
preparation for CPU hotplugging.

which prevented the driver from building.

Via Dave Jones.

  - me/Al Viro: fix bdget() oops with block device modules that don't
  clean up after they exit
  - Alan Cox: continued merging (drivers, license tags)
  - David Miller: sparc update, network fixes
  - Christoph Hellwig: work around broken drivers that add a gendisk more
  than once
  - Jakub Jelinek: handle more ELF loading special cases
  - Trond Myklebust: NFS client and lockd reclaimer cleanups/fixes
  - Greg KH: USB updates
  - Mikael Pettersson: sparate out local APIC / IO-APIC config options

  - 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

  - Andreas Dilger: various ext2 cleanups
  - Richard Gooch: devfs update
  - Johannes Erdfelt: USB updates
  - Alan Cox: merges
  - David Miller: fix SMP pktsched bootup deadlock (CONFIG_NET_SCHED)
  - Roman Zippel: AFFS update
  - Anton Altaparmakov: NTFS update
  - me: fix races in vfork() (semaphores are not good completion handlers)
  - Jeff Garzik: net driver updates, sysvfs update

  - Chris Mason: ReiserFS pre-allocation locking bugfix
  - David Miller: fix bitops users (requires "long" alignment)
  - Andrey Savochkin: file locking failure case SMP lock fix
  - Urban Widmark: smbfs update (avoid unnecessary flushing, make NetApp
  work)
  - Andrew Grover: ACPI update
  - Jeff Garzik: network driver updates
  - Maciej Rozycki: IO-APIC level trigger problem workaround
  - Rusty Russell: ipt_unclean fix
  - Richard Gooch: devfs update

  - big S/390x 64-bit merge
  - typos and license name fixes. doc updates.
  - more include file cleanups (phase out "malloc.h")
  - even more elevator corner cases.. When not merging, find the best insertion point.
  - pmac ide update
  - network fixes (netif_wake_queue on tx timeout)
  - USB printer select() fix
  - NFS client missed initialization, deamon fixed client address check