In preparation for adding support for quiescing timers in the final
stage of suspend-to-idle transitions, rework the freeze_enter()
function making the system wait on a wakeup event, the freeze_wake()
function terminating the suspend-to-idle loop and the mechanism by
which deep idle states are entered during suspend-to-idle.

First of all, introduce a simple state machine for suspend-to-idle
and make the code in question use it.

Second, prevent freeze_enter() from losing wakeup events due to race
conditions and ensure that the number of online CPUs won't change
while it is being executed.  In addition to that, make it force
all of the CPUs re-enter the idle loop in case they are in idle
states already (so they can enter deeper idle states if possible).

Next, drop cpuidle_use_deepest_state() and replace use_deepest_state
checks in cpuidle_select() and cpuidle_reflect() with a single
suspend-to-idle state check in cpuidle_idle_call().

Finally, introduce cpuidle_enter_freeze() that will simply find the
deepest idle state available to the given CPU and enter it using
cpuidle_enter().
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>

cpu_idle_poll() is entered into when either the cpu_idle_force_poll is set or
tick_check_broadcast_expired() returns true. The exit condition from
cpu_idle_poll() is tif_need_resched().

However this does not take into account scenarios where cpu_idle_force_poll
changes or tick_check_broadcast_expired() returns false, without setting
the resched flag. So a cpu will be caught in cpu_idle_poll() needlessly,
thereby wasting power. Add an explicit check on cpu_idle_force_poll and
tick_check_broadcast_expired() to the exit condition of cpu_idle_poll()
to avoid this.
Signed-off-by: NPreeti U Murthy <preeti@linux.vnet.ibm.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20150121105655.15279.59626.stgit@preeti.in.ibm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

When the cpu enters idle, it stores the cpuidle state pointer in its
struct rq instance which in turn could be used to make a better decision
when balancing tasks.

As soon as the cpu exits its idle state, the struct rq reference is
cleared.

There are a couple of situations where the idle state pointer could be changed
while it is being consulted:

1. For x86/acpi with dynamic c-states, when a laptop switches from battery
   to AC that could result on removing the deeper idle state. The acpi driver
   triggers:
	'acpi_processor_cst_has_changed'
		'cpuidle_pause_and_lock'
			'cpuidle_uninstall_idle_handler'
				'kick_all_cpus_sync'.

All cpus will exit their idle state and the pointed object will be set to
NULL.

2. The cpuidle driver is unloaded. Logically that could happen but not
in practice because the drivers are always compiled in and 95% of them are
not coded to unregister themselves.  In any case, the unloading code must
call 'cpuidle_unregister_device', that calls 'cpuidle_pause_and_lock'
leading to 'kick_all_cpus_sync' as mentioned above.

A race can happen if we use the pointer and then one of these two scenarios
occurs at the same moment.

In order to be safe, the idle state pointer stored in the rq must be
used inside a rcu_read_lock section where we are protected with the
'rcu_barrier' in the 'cpuidle_uninstall_idle_handler' function. The
idle_get_state() and idle_put_state() accessors should be used to that
effect.
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
Cc: linaro-kernel@lists.linaro.org
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

idle_exit event is the first event after a core exits
idle state. So this should be traced before local irq
is ebabled. Likewise idle_entry is the last event before
a core enters idle state. This will ease visualising the
cpu idle state from kernel traces.
Signed-off-by: NSandeep Tripathy <sandeep.tripathy@linaro.org>
Acked-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
[rjw: Subject, rebase]
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

We don't need 'broadcast' to be set to 'zero or one', but to 'zero or non-zero'
and so the extra operation to convert it to 'zero or one' can be skipped.

Also change type of 'broadcast' to unsigned int, i.e. type of
drv->states[*].flags.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/0dfbe2976aa108c53e08d3477ea90f6360c1f54c.1403584026.git.viresh.kumar@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

[ This series reduces the number of IPIs on Andy's workload by something like
  99%. It's down from many hundreds per second to very few.

  The basic idea behind this series is to make TIF_POLLING_NRFLAG be a
  reliable indication that the idle task is polling.  Once that's done,
  the rest is reasonably straightforward. ]

When enqueueing tasks on remote LLC domains, we send an IPI to do the
work 'locally' and avoid bouncing all the cachelines over.

However, when the remote CPU is idle (and polling, say x86 mwait), we
don't need to send an IPI, we can simply kick the TIF word to wake it
up and have the 'idle' loop do the work.

So when _TIF_POLLING_NRFLAG is set, but _TIF_NEED_RESCHED is not (yet)
set, set _TIF_NEED_RESCHED and avoid sending the IPI.
Much-requested-by: NAndy Lutomirski <luto@amacapital.net>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
[Edited by Andy Lutomirski, but this is mostly Peter Zijlstra's code.]
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Cc: nicolas.pitre@linaro.org
Cc: daniel.lezcano@linaro.org
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: umgwanakikbuti@gmail.com
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/ce06f8b02e7e337be63e97597fc4b248d3aa6f9b.1401902905.git.luto@amacapital.netSigned-off-by: NIngo Molnar <mingo@kernel.org>

Currently, the only real guarantee provided by the polling bit is
that, if you hold rq->lock and the polling bit is set, then you can
set need_resched to force a reschedule.

The only reason the lock is needed is that the idle thread might not
be running at all when setting its need_resched bit, and rq->lock
keeps it pinned.

This is easy to fix: just clear the polling bit before scheduling.
Now the idle thread's polling bit is only ever set when
rq->curr == rq->idle.
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Cc: nicolas.pitre@linaro.org
Cc: daniel.lezcano@linaro.org
Cc: umgwanakikbuti@gmail.com
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/b2059fcb4c613d520cb503b6fad6e47033c7c203.1401902905.git.luto@amacapital.netSigned-off-by: NIngo Molnar <mingo@kernel.org>

The only value ever returned by cpuidle_idle_call() is 0 and its
only caller ignores that value anyway, so make it void.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/4717784.WmVEpDoliM@vostro.rjw.lanSigned-off-by: NIngo Molnar <mingo@kernel.org>

Apply goto to reduce lines and nesting levels.
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Acked-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-cc6vb0snt3sr7op6rlbfeqfh@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

With the generic idle functions assuming !polling we should only clear
the polling bit at the very last opportunity in order to avoid
spurious IPIs.

Ideally we'd flip the default to polling, but that means auditing all
arch idle functions.
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Acked-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-vq7719foqzf6z5h4j7eh7f9e@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Since both cpuidle_enabled() and cpuidle_select() are only called by
cpuidle_idle_call(), it is not really useful to keep them separate
and combining them will help to avoid complicating cpuidle_idle_call()
even further if governors are changed to return error codes sometimes.

This code modification shouldn't lead to any functional changes.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

The idle main function is a complex and a critical function. Added more
comments to the code.
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: rjw@rjwysocki.net
Cc: preeti@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1393832934-11625-5-git-send-email-daniel.lezcano@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

This patch moves the condition before entering idle into the cpuidle main
function located in idle.c. That simplify the idle mainloop functions and
increase the readibility of the conditions to enter truly idle.

This patch is code reorganization and does not change the behavior of the
function.
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: rjw@rjwysocki.net
Cc: nicolas.pitre@linaro.org
Cc: preeti@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1393832934-11625-4-git-send-email-daniel.lezcano@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Now that we have the main cpuidle function in idle.c, move some code from
the idle mainloop to this function for the sake of clarity.

That removes if then else indentation difficult to follow when looking at the
code. This patch does not change the current behavior.
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: rjw@rjwysocki.net
Cc: preeti@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1393832934-11625-3-git-send-email-daniel.lezcano@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

The cpuidle_idle_call does nothing more than calling the three individuals
function and is no longer used by any arch specific code but only in the
cpuidle framework code.

We can move this function into the idle task code to ensure better
proximity to the scheduler code.
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Cc: rjw@rjwysocki.net
Cc: preeti@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1393832934-11625-2-git-send-email-daniel.lezcano@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Commit cf37b6b4 ("sched/idle: Move cpu/idle.c to sched/idle.c")
said to simply move a file; somehow it got mangled and created an old
version of the file and forgot to remove the old file.

Fix this fail; add the lost change and remove the now identical old
file.
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Cc: rjw@rjwysocki.net
Cc: nicolas.pitre@linaro.org
Cc: preeti@linux.vnet.ibm.com
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: http://lkml.kernel.org/r/20140224172207.GC9987@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>

Integration of cpuidle with the scheduler requires that the idle loop be
closely integrated with the scheduler proper. Moving cpu/idle.c into the
sched directory will allow for a smoother integration, and eliminate a
subdirectory which contained only one source file.
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/alpine.LFD.2.11.1401301102210.1652@knanqh.ubzrSigned-off-by: NIngo Molnar <mingo@kernel.org>

In order to integrate cpuidle with the scheduler, we must have a better
proximity in the core code with what cpuidle is doing and not delegate
such interaction to arch code.

Architectures implementing arch_cpu_idle() should simply enter
a cheap idle mode in the absence of a proper cpuidle driver.

In both cases i.e. whether it is a cpuidle driver or the default
arch_cpu_idle(), the calling convention expects IRQs to be disabled
on entry and enabled on exit. There is a warning in place already but
let's add a forced IRQ enable here as well.  This will allow for
removing the forced IRQ enable some implementations do locally and
allowing for the warning to trig.
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Acked-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Olof Johansson <olof@lixom.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.11.1401291526320.1652@knanqh.ubzrSigned-off-by: NIngo Molnar <mingo@kernel.org>

With various drivers wanting to inject idle time; we get people
calling idle routines outside of the idle loop proper.

Therefore we need to be extra careful about not missing
TIF_NEED_RESCHED -> PREEMPT_NEED_RESCHED propagations.

While looking at this, I also realized there's a small window in the
existing idle loop where we can miss TIF_NEED_RESCHED; when it hits
right after the tif_need_resched() test at the end of the loop but
right before the need_resched() test at the start of the loop.

So move preempt_fold_need_resched() out of the loop where we're
guaranteed to have TIF_NEED_RESCHED set.
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-x9jgh45oeayzajz2mjt0y7d6@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

In order to combine the preemption and need_resched test we need to
fold the need_resched information into the preempt_count value.

Since the NEED_RESCHED flag is set across CPUs this needs to be an
atomic operation, however we very much want to avoid making
preempt_count atomic, therefore we keep the existing TIF_NEED_RESCHED
infrastructure in place but at 3 sites test it and fold its value into
preempt_count; namely:

 - resched_task() when setting TIF_NEED_RESCHED on the current task
 - scheduler_ipi() when resched_task() sets TIF_NEED_RESCHED on a
                   remote task it follows it up with a reschedule IPI
                   and we can modify the cpu local preempt_count from
                   there.
 - cpu_idle_loop() for when resched_task() found tsk_is_polling().

We use an inverted bitmask to indicate need_resched so that a 0 means
both need_resched and !atomic.

Also remove the barrier() in preempt_enable() between
preempt_enable_no_resched() and preempt_check_resched() to avoid
having to reload the preemption value and allow the compiler to use
the flags of the previuos decrement. I couldn't come up with any sane
reason for this barrier() to be there as preempt_enable_no_resched()
already has a barrier() before doing the decrement.
Suggested-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-7a7m5qqbn5pmwnd4wko9u6da@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Mike reported that commit 7d1a9417 ("x86: Use generic idle loop")
regressed several workloads and caused excessive reschedule
interrupts.

The patch in question failed to notice that the x86 code had an
inverted sense of the polling state versus the new generic code (x86:
default polling, generic: default !polling).

Fix the two prominent x86 mwait based idle drivers and introduce a few
new generic polling helpers (fixing the wrong smp_mb__after_clear_bit
usage).

Also switch the idle routines to using tif_need_resched() which is an
immediate TIF_NEED_RESCHED test as opposed to need_resched which will
end up being slightly different.
Reported-by: NMike Galbraith <bitbucket@online.de>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Cc: lenb@kernel.org
Cc: tglx@linutronix.de
Link: http://lkml.kernel.org/n/tip-nc03imb0etuefmzybzj7sprf@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

PARISC bootup triggers the warning at kernel/cpu/idle.c:96. That's
caused by the weak arch_cpu_idle() implementation, which is provided
to avoid that architectures implement idle_poll over and over.

The switchover to polling mode happens in the first call of the weak
arch_cpu_idle() implementation, but that code fails to reenable
interrupts and therefor triggers the warning.

Fix this by enabling interrupts in the weak arch_cpu_idle() code.

[ tglx: Made the changelog match the patch ]
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>
Reviewed-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1371236142.2726.43.camel@dabdikeSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Moving x86 to the generic idle implementation (commit 7d1a9417 "x86:
Use generic idle loop") wreckaged the stack protector.

I stupidly missed that boot_init_stack_canary() must be inlined from a
function which never returns, but I put that call into
arch_cpu_idle_prepare() which of course returns.

I pondered to play tricks with arch_cpu_idle_prepare() first, but then
I noticed, that the other archs which have implemented the
stackprotector (ARM and SH) do not initialize the canary for the
non-boot cpus.

So I decided to move the boot_init_stack_canary() call into
cpu_startup_entry() ifdeffed with an CONFIG_X86 for now. This #ifdef
is just a temporary measure as I don't want to inflict the
boot_init_stack_canary() call on ARM and SH that late in the cycle.

I'll queue a patch for 3.11 which removes the #ifdef if the ARM/SH
maintainers have no objection.
Reported-by: NWouter van Kesteren <woutershep@gmail.com>
Cc: x86@kernel.org
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Bjørn Mork reported the following warning when running powertop.

[   49.289034] ------------[ cut here ]------------
[   49.289055] WARNING: at kernel/rcutree.c:502 rcu_eqs_exit_common.isra.48+0x3d/0x125()
[   49.289244] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.10.0-bisect-rcu-warn+ #107
[   49.289251]  ffffffff8157d8c8 ffffffff81801e28 ffffffff8137e4e3 ffffffff81801e68
[   49.289260]  ffffffff8103094f ffffffff81801e68 0000000000000000 ffff88023afcd9b0
[   49.289268]  0000000000000000 0140000000000000 ffff88023bee7700 ffffffff81801e78
[   49.289276] Call Trace:
[   49.289285]  [<ffffffff8137e4e3>] dump_stack+0x19/0x1b
[   49.289293]  [<ffffffff8103094f>] warn_slowpath_common+0x62/0x7b
[   49.289300]  [<ffffffff8103097d>] warn_slowpath_null+0x15/0x17
[   49.289306]  [<ffffffff810a9006>] rcu_eqs_exit_common.isra.48+0x3d/0x125
[   49.289314]  [<ffffffff81079b49>] ? trace_hardirqs_off_caller+0x37/0xa6
[   49.289320]  [<ffffffff810a9692>] rcu_idle_exit+0x85/0xa8
[   49.289327]  [<ffffffff8107076e>] trace_cpu_idle_rcuidle+0xae/0xff
[   49.289334]  [<ffffffff810708b1>] cpu_startup_entry+0x72/0x115
[   49.289341]  [<ffffffff813689e5>] rest_init+0x149/0x150
[   49.289347]  [<ffffffff8136889c>] ? csum_partial_copy_generic+0x16c/0x16c
[   49.289355]  [<ffffffff81a82d34>] start_kernel+0x3f0/0x3fd
[   49.289362]  [<ffffffff81a8274c>] ? repair_env_string+0x5a/0x5a
[   49.289368]  [<ffffffff81a82481>] x86_64_start_reservations+0x2a/0x2c
[   49.289375]  [<ffffffff81a82550>] x86_64_start_kernel+0xcd/0xd1
[   49.289379] ---[ end trace 07a1cc95e29e9036 ]---

The warning is that 'rdtp->dynticks' has an unexpected value, which roughly
translates to - the calls to rcu_idle_enter() and rcu_idle_exit() were not
made in the correct order, or otherwise messed up.

And Bjørn's painstaking debugging indicated that this happens when the idle
loop enters the poll mode. Looking at the poll function cpu_idle_poll(), and
the implementation of trace_cpu_idle_rcuidle(), the problem becomes very clear:
cpu_idle_poll() lacks calls to rcu_idle_enter/exit(), and trace_cpu_idle_rcuidle()
calls them in the reverse order - first rcu_idle_exit(), and then rcu_idle_enter().
Hence the even/odd alternative sequencing of rdtp->dynticks goes for a toss.

And powertop readily triggers this because powertop uses the idle-tracing
infrastructure extensively.

So, to fix this, wrap the code in cpu_idle_poll() within rcu_idle_enter/exit(),
so that it blends properly with the calls inside trace_cpu_idle_rcuidle() and
thus get the function ordering right.
Reported-and-tested-by: NBjørn Mork <bjorn@mork.no>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/519169BF.4080208@linux.vnet.ibm.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

All archs are converted over. Remove the config switch and the
fallback code.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

All idle functions in arch/* are more or less the same, plus minus a
few bugs and extra instrumentation, tickless support and other
optional items.

Implement a generic idle function which resembles the functionality
found in arch/. Provide weak arch_cpu_idle_* functions which can be
overridden by the architecture code if needed.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: NCc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130321215233.646635455@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

For now this calls cpu_idle(), but in the long run we want to move the
cpu bringup code to the core and therefor we add a state argument.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: NCc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130321215233.583190032@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>