sysfs is now completely out of driver/module lifetime game.  After
deletion, a sysfs node doesn't access anything outside sysfs proper,
so there's no reason to hold onto the attribute owners.  Note that
often the wrong modules were accounted for as owners leading to
accessing removed modules.

This patch kills now unnecessary attribute->owner.  Note that with
this change, userland holding a sysfs node does not prevent the
backing module from being unloaded.

For more info regarding lifetime rule cleanup, please read the
following message.

  http://article.gmane.org/gmane.linux.kernel/510293

(tweaked by Greg to not delete the field just yet, to make it easier to
merge things properly.)
Signed-off-by: NTejun Heo <htejun@gmail.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The name 'pin' was badly chosen, it doesn't pin a pipe buffer
in the most commonly used sense in the kernel. So change the
name to 'confirm', after debating this issue with Hugh
Dickins a bit.

A good return from ->confirm() means that the buffer is really
there, and that the contents are good.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

It cleans up the relay splice implementation a lot, and gets rid of
a lot of internal pipe knowledge that should not be in there.

Plus fixes for padding and partial first page (and lots more) from
Tom Zanussi.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

We need to move even more stuff into the header so that folks can use
the splice_to_pipe() implementation instead of open-coding a lot of
pipe knowledge (see relay implementation), so move to our own header
file finally.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

add credits for recent major scheduler contributions:

  Con Kolivas, for pioneering the fair-scheduling approach
  Peter Williams, for smpnice
  Mike Galbraith, for interactivity tuning of CFS
  Srivatsa Vaddagiri, for group scheduling enhancements
Signed-off-by: NIngo Molnar <mingo@elte.hu>

clean up the sleep_on() APIs:

 - do not use fastcall
 - replace fragile macro magic with proper inline functions
Signed-off-by: NIngo Molnar <mingo@elte.hu>

4 small style cleanups to sched.c: checkpatch.pl is now happy about
the totality of sched.c [ignoring false positives] - yay! ;-)
Signed-off-by: NIngo Molnar <mingo@elte.hu>

do not set softirqs to nice +19. _If_ for whatever reason
we missed to process some high-prio softirq and woke up
ksoftirqd, we should give it a fair chance to actually
get some work done, even if the system is under load.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

scheduler debugging core: implement /proc/sched_debug and
/proc/<PID>/sched files for scheduler debugging.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

add CFS debug sysctls: only tweakable if SCHED_DEBUG is enabled.
This allows for faster debugging of scheduler problems.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

remove unused rq types from sched.c, now that we switched
over to CFS.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

remove now unused interactivity-heuristics related defined and
types of the old scheduler.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

clean up include files in sched.c, they were still old-style <asm/>.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

update delay-accounting to use CFS's precise stats.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

make use of sched-clock-unstable events.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

track TSC-unstable events and propagate it to the scheduler code.
Also allow sched_clock() to be used when the TSC is unstable,
the rq_clock() wrapper creates a reliable clock out of it.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

apply the CFS core code.

this change switches over the scheduler core to CFS's modular
design and makes use of kernel/sched_fair/rt/idletask.c to implement
Linux's scheduling policies.

thanks to Andrew Morton and Thomas Gleixner for lots of detailed review
feedback and for fixlets.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: NSrivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>

remove the sleep-bonus interactivity code from the core scheduler.

scheduling policy is implemented in the policy modules, and CFS does
not need such type of heuristics.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

remove the expired_starving() heuristics from the core scheduler.

CFS does not need it, and this did not really work well in practice
anyway, due to the rq->nr_running multiplier to STARVATION_LIMIT.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

remove the sleep_type heuristics from the core scheduler - scheduling
policy is implemented in the scheduling-policy modules. (and CFS does
not use this type of sleep-type heuristics)
Signed-off-by: NIngo Molnar <mingo@elte.hu>

add the new load-calculation methods of CFS.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

clean up: move __normal_prio() in head of normal_prio().

no code changed.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

cleanup: move dequeue/enqueue_task() to a more logical place, to
not split up __normal_prio()/normal_prio().
Signed-off-by: NIngo Molnar <mingo@elte.hu>

move resched_task()/resched_cpu() into the 'public interfaces'
section of sched.c, for use by kernel/sched_fair/rt/idletask.c
Signed-off-by: NIngo Molnar <mingo@elte.hu>

clean up the rt priority macros, pointed out by Andrew Morton.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

add the set_task_cfs_rq() abstraction needed by CONFIG_FAIR_GROUP_SCHED.

(not activated yet)
Signed-off-by: NIngo Molnar <mingo@elte.hu>

update the posix-cpu-timers code to use CFS's CPU accounting information.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

add rq_clock()/__rq_clock(), a robust wrapper around sched_clock(),
used by CFS. It protects against common type of sched_clock() problems
(caused by hardware): time warps forwards and backwards.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

add the CFS rq data types to sched.c.

(the old scheduler fields are still intact, they are removed
 by a later patch)
Signed-off-by: NIngo Molnar <mingo@elte.hu>

add kernel/sched_idletask.c - which implements the idle thread
scheduling class. This further simplifies sched.c (under CFS),
for example a number of 'if (p == rq->idle)' type of special-cases
can be removed from sched.c, and schedule() gets simpler too.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

add kernel/sched_rt.c: SCHED_FIFO/SCHED_RR support. The behavior
and semantics of SCHED_FIFO/SCHED_RR tasks is unchanged.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

add kernel/sched_fair.c - which implements the bulk of CFS's
behavioral changes for SCHED_OTHER tasks.

see Documentation/sched-design-CFS.txt about details.

Authors:

 Ingo Molnar <mingo@elte.hu>
 Dmitry Adamushko <dmitry.adamushko@gmail.com>
 Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
 Mike Galbraith <efault@gmx.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: NSrivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>

create sched_stats.h and move sched.c schedstats code into it.
This cleans up sched.c a bit.

no code changes are caused by this patch.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

add the init_idle_bootup_task() callback to the bootup thread,
unused at the moment. (CFS will use it to switch the scheduling
class of the boot thread to the idle class)
Signed-off-by: NIngo Molnar <mingo@elte.hu>

remove sched_exit(): the elaborate dance of us trying to recover
timeslices given to child tasks never really worked.

CFS does not need it either.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

uninline set_task_cpu(): CFS will add more code to it.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

the SMP load-balancer uses the boot-time migration-cost estimation
code to attempt to improve the quality of balancing. The reason for
this code is that the discrete priority queues do not preserve
the order of scheduling accurately, so the load-balancer skips
tasks that were running on a CPU 'recently'.

this code is fundamental fragile: the boot-time migration cost detector
doesnt really work on systems that had large L3 caches, it caused boot
delays on large systems and the whole cache-hot concept made the
balancing code pretty undeterministic as well.

(and hey, i wrote most of it, so i can say it out loud that it sucks ;-)

under CFS the same purpose of cache affinity can be achieved without
any special cache-hot special-case: tasks are sorted in the 'timeline'
tree and the SMP balancer picks tasks from the left side of the
tree, thus the most cache-cold task is balanced automatically.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

enum idle_type (used by the load-balancer) clashes with the
SCHED_IDLE name that we want to introduce. 'CPU_IDLE' instead
of 'SCHED_IDLE' is more descriptive as well.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The clock_was_set() call in seconds_overflow() which happens only when
leap seconds are inserted / deleted is wrong in two aspects:

1. it results in a call to on_each_cpu() with interrupts disabled
2. it is potential deadlock source vs. call_lock in smp_call_function()

The only possible side effect of the removal might be, that an absolute
CLOCK_REALTIME timer fires 1 second too late, in the rare case of leap
second deletion and an absolute CLOCK_REALTIME timer which expires in
the affected time frame. It will never fire too early.

This was probably observed by the reporter of a June 30th -> July 1st
hang: http://lkml.org/lkml/2007/7/3/103

A similar problem was observed by Dave Jones, who provided a screen shot
with a lockdep back trace, which allowed to analyse the problem.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>