There is a number of cases where a kernel subsystem may want to
introspect the state of an interrupt at the irqchip level:

- When a peripheral is shared between virtual machines,
  its interrupt state becomes part of the guest's state,
  and must be switched accordingly. KVM on arm/arm64 requires
  this for its guest-visible timer
- Some GPIO controllers seem to require peeking into the
  interrupt controller they are connected to to report
  their internal state

This seem to be a pattern that is common enough for the core code
to try and support this without too many horrible hacks. Introduce
a pair of accessors (irq_get_irqchip_state/irq_set_irqchip_state)
to retrieve the bits that can be of interest to another subsystem:
pending, active, and masked.

- irq_get_irqchip_state returns the state of the interrupt according
  to a parameter set to IRQCHIP_STATE_PENDING, IRQCHIP_STATE_ACTIVE,
  IRQCHIP_STATE_MASKED or IRQCHIP_STATE_LINE_LEVEL.
- irq_set_irqchip_state similarly sets the state of the interrupt.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: NBjorn Andersson <bjorn.andersson@sonymobile.com>
Tested-by: NBjorn Andersson <bjorn.andersson@sonymobile.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Phong Vo <pvo@apm.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Tin Huynh <tnhuynh@apm.com>
Cc: Y Vo <yvo@apm.com>
Cc: Toan Le <toanle@apm.com>
Cc: Bjorn Andersson <bjorn@kryo.se>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Link: http://lkml.kernel.org/r/1426676484-21812-2-git-send-email-marc.zyngier@arm.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

The IRQF_DISABLED flag is a NOOP and has been scheduled for removal
since Linux v2.6.36 by commit 6932bf37 ("genirq: Remove
IRQF_DISABLED from core code").

According to commit e58aa3d2 ("genirq: Run irq handlers with
interrupts disabled"), running IRQ handlers with interrupts
enabled can cause stack overflows when the interrupt line of the
issuing device is still active.

This patch ends the grace period for IRQF_DISABLED (i.e.,
SA_INTERRUPT in older versions of Linux) and removes the
definition and all remaining usages of this flag.

There's still a few non-functional references left in the kernel
source:

  - The bigger hunk in Documentation/scsi/ncr53c8xx.txt is removed entirely
    as IRQF_DISABLED is gone now; the usage in older kernel versions
    (including the old SA_INTERRUPT flag) should be discouraged.  The
    trouble of using IRQF_SHARED is a general problem and not specific to
    any driver.

  - I left the reference in Documentation/PCI/MSI-HOWTO.txt untouched since
    it has already been removed in linux-next.

  - All remaining references are changelogs that I suggest to keep.
Signed-off-by: NValentin Rothberg <valentinrothberg@gmail.com>
Cc: Afzal Mohammed <afzal@ti.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Ewan Milne <emilne@redhat.com>
Cc: Eyal Perry <eyalpe@mellanox.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Hongliang Tao <taohl@lemote.com>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Keerthy <j-keerthy@ti.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nishanth Menon <nm@ti.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Lambert <lambert.quentin@gmail.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Sricharan R <r.sricharan@ti.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Zhou Wang <wangzhou1@hisilicon.com>
Cc: iss_storagedev@hp.com
Cc: linux-mips@linux-mips.org
Cc: linux-mtd@lists.infradead.org
Link: http://lkml.kernel.org/r/1425565425-12604-1-git-send-email-valentinrothberg@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

It currently is required that all users of NO_SUSPEND interrupt
lines pass the IRQF_NO_SUSPEND flag when requesting the IRQ or the
WARN_ON_ONCE() in irq_pm_install_action() will trigger.  That is
done to warn about situations in which unprepared interrupt handlers
may be run unnecessarily for suspended devices and may attempt to
access those devices by mistake.  However, it may cause drivers
that have no technical reasons for using IRQF_NO_SUSPEND to set
that flag just because they happen to share the interrupt line
with something like a timer.

Moreover, the generic handling of wakeup interrupts introduced by
commit 9ce7a258 (genirq: Simplify wakeup mechanism) only works
for IRQs without any NO_SUSPEND users, so the drivers of wakeup
devices needing to use shared NO_SUSPEND interrupt lines for
signaling system wakeup generally have to detect wakeup in their
interrupt handlers.  Thus if they happen to share an interrupt line
with a NO_SUSPEND user, they also need to request that their
interrupt handlers be run after suspend_device_irqs().

In both cases the reason for using IRQF_NO_SUSPEND is not because
the driver in question has a genuine need to run its interrupt
handler after suspend_device_irqs(), but because it happens to
share the line with some other NO_SUSPEND user.  Otherwise, the
driver would do without IRQF_NO_SUSPEND just fine.

To make it possible to specify that condition explicitly, introduce
a new IRQ action handler flag for shared IRQs, IRQF_COND_SUSPEND,
that, when set, will indicate to the IRQ core that the interrupt
user is generally fine with suspending the IRQ, but it also can
tolerate handler invocations after suspend_device_irqs() and, in
particular, it is capable of detecting system wakeup and triggering
it as appropriate from its interrupt handler.

That will allow us to work around a problem with a shared timer
interrupt line on at91 platforms.

Link: http://marc.info/?l=linux-kernel&m=142252777602084&w=2
Link: http://marc.info/?t=142252775300011&r=1&w=2
Link: https://lkml.org/lkml/2014/12/15/552Reported-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NMark Rutland <mark.rutland@arm.com>

The IRQF_NO_SUSPEND flag is intended to be used for interrupts required
to be enabled during the suspend-resume cycle. This mostly consists of
IPIs and timer interrupts, potentially including chained irqchip
interrupts if these are necessary to handle timers or IPIs. If an
interrupt does not fall into one of the aforementioned categories,
requesting it with IRQF_NO_SUSPEND is likely incorrect.

Using IRQF_NO_SUSPEND does not guarantee that the interrupt can wake the
system from a suspended state. For an interrupt to be able to trigger a
wakeup, it may be necessary to program various components of the system.
In these cases it is necessary to use {enable,disabled}_irq_wake.

Unfortunately, several drivers assume that IRQF_NO_SUSPEND ensures that
an IRQ can wake up the system, and the documentation can be read
ambiguously w.r.t. this property.

This patch updates the documentation regarding IRQF_NO_SUSPEND to make
this caveat explicit, hopefully making future misuse rarer. Cleanup of
existing misuse will occur as part of later patch series.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

For things like netpoll there is a need to disable an interrupt from
atomic context. Currently netpoll uses disable_irq() which will
sleep-wait on threaded handlers and thus forced_irqthreads breaks
things.

Provide disable_hardirq(), which uses synchronize_hardirq() to only wait
for active hardirq handlers; also change synchronize_hardirq() to
return the status of threaded handlers.

This will allow one to try-disable an interrupt from atomic context, or
in case of request_threaded_irq() to only wait for the hardirq part.
Suggested-by: NSabrina Dubroca <sd@queasysnail.net>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Miller <davem@davemloft.net>
Cc: Eyal Perry <eyalpe@mellanox.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Quentin Lambert <lambert.quentin@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>
Link: http://lkml.kernel.org/r/20150205130623.GH5029@twins.programming.kicks-ass.net
[ Fixed typos and such. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Signed-off-by: NQuentin Lambert <lambert.quentin@gmail.com>
Signed-off-by: NValentin Rothberg <valentinrothberg@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently we suspend wakeup interrupts by lazy disabling them and
check later whether the interrupt has fired, but that's not sufficient
for suspend to idle as there is no way to check that once we
transitioned into the CPU idle state.

So we change the mechanism in the following way:

1) Leave the wakeup interrupts enabled across suspend

2) Add a check to irq_may_run() which is called at the beginning of
   each flow handler whether the interrupt is an armed wakeup source.

   This check is basically free as it just extends the existing check
   for IRQD_IRQ_INPROGRESS. So no new conditional in the hot path.

   If the IRQD_WAKEUP_ARMED flag is set, then the interrupt is
   disabled, marked as pending/suspended and the pm core is notified
   about the wakeup event.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
[ rjw: syscore.c and put irq_pm_check_wakeup() into pm.c ]
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Instead of requiring each consumer of the IRQ affinity notifier to have
themselves be explicitly dependent on CONFIG_SMP, make the definition of
struct irq_affinity_notify to exist independently of that config option
and introduce a stub for irq_set_affinity_notifier() under non SMP
configuration.

Fixes: 2eacc23c ("net/mlx4_core: Enforce irq affinity changes
immediatly")
Signed-off-by: NEyal Perry <eyalpe@mellanox.com>
Signed-off-by: NAmir Vadai <amirv@mellanox.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Yevgeny Petrilin <yevgenyp@mellanox.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Cc: David S. Miller <davem@davemloft.net>
Link: http://lkml.kernel.org/r/1400597820-30685-1-git-send-email-amirv@mellanox.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Patch 01f8fa4f "genirq: Allow forcing cpu affinity of interrupts" added
an irq_force_affinity() function, and 30ccf03b "clocksource: Exynos_mct:
Use irq_force_affinity() in cpu bringup" subsequently uses it. However, the
driver can be used with CONFIG_SMP disabled, but the function declaration
is only available for CONFIG_SMP, leading to this build error:

drivers/clocksource/exynos_mct.c:431:3: error: implicit declaration of function 'irq_force_affinity' [-Werror=implicit-function-declaration]
   irq_force_affinity(mct_irqs[MCT_L0_IRQ + cpu], cpumask_of(cpu));

This patch introduces a dummy helper function for the non-SMP case
that always returns success, to get rid of the build error.
Since the patches causing the problem are marked for stable backports,
this one should be as well.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: NKukjin Kim <kgene.kim@samsung.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/5619084.0zmrrIUZLV@wuerfelSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Fix new kernel-doc warnings in <linux/interrupt.h>:

Warning(include/linux/interrupt.h:219): No description found for parameter 'cpumask'
Warning(include/linux/interrupt.h:219): Excess function parameter 'mask' description in 'irq_set_affinity'
Warning(include/linux/interrupt.h:236): No description found for parameter 'cpumask'
Warning(include/linux/interrupt.h:236): Excess function parameter 'mask' description in 'irq_force_affinity'
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Link: http://lkml.kernel.org/r/535DD2FD.7030804@infradead.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Mostly scripted conversion of the smp_mb__* barriers.
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/n/tip-55dhyhocezdw1dg7u19hmh1u@git.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-arch@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

The current implementation of irq_set_affinity() refuses rightfully to
route an interrupt to an offline cpu.

But there is a special case, where this is actually desired. Some of
the ARM SoCs have per cpu timers which require setting the affinity
during cpu startup where the cpu is not yet in the online mask.

If we can't do that, then the local timer interrupt for the about to
become online cpu is routed to some random online cpu.

The developers of the affected machines tried to work around that
issue, but that results in a massive mess in that timer code.

We have a yet unused argument in the set_affinity callbacks of the irq
chips, which I added back then for a similar reason. It was never
required so it got not used. But I'm happy that I never removed it.

That allows us to implement a sane handling of the above scenario. So
the affected SoC drivers can add the required force handling to their
interrupt chip, switch the timer code to irq_force_affinity() and
things just work.

This does not affect any existing user of irq_set_affinity().

Tagged for stable to allow a simple fix of the affected SoC clock
event drivers.
Reported-and-tested-by: NKrzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Tomasz Figa <t.figa@samsung.com>,
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: linux-arm-kernel@lists.infradead.org,
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20140416143315.717251504@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

In course of the sdhci/sdio discussion with Russell about killing the
sdio kthread hackery we discovered the need to be able to wake an
interrupt thread from software.

The rationale for this is, that sdio hardware can lack proper
interrupt support for certain features. So the driver needs to poll
the status registers, but at the same time it needs to be woken up by
an hardware interrupt.

To be able to get rid of the home brewn kthread construct of sdio we
need a way to wake an irq thread independent of an actual hardware
interrupt.

Provide an irq_wake_thread() function which wakes up the thread which
is associated to a given dev_id. This allows sdio to invoke the irq
thread from the hardware irq handler via the IRQ_WAKE_THREAD return
value and provides a possibility to wake it via a timer for the
polling scenarios. That allows to simplify the sdio logic
significantly.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Chris Ball <chris@printf.net>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140215003823.772565780@linutronix.de

Some drivers use request_any_context_irq() but there isn't a
devm_* function for it. Add one so that these drivers don't need
to explicitly free the irq on driver detach.
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Link: http://lkml.kernel.org/r/1388709460-19222-3-git-send-email-sboyd@codeaurora.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Reduce data size a little.
Reduce checkpatch noise.

$ size kernel/softirq.o*
   text	   data	    bss	    dec	    hex	filename
  11554	   6013	   4008	  21575	   5447	kernel/softirq.o.new
  11474	   6093	   4008	  21575	   5447	kernel/softirq.o.old
Signed-off-by: NJoe Perches <joe@perches.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This commit was incomplete in that code to remove items from the per-cpu
lists was missing and never acquired a user in the 5 years it has been in
the tree.  We're going to implement what it seems to try to archive in a
simpler way, and this code is in the way of doing so.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

All arch overriden implementations of do_softirq() share the following
common code: disable irqs (to avoid races with the pending check),
check if there are softirqs pending, then execute __do_softirq() on
a specific stack.

Consolidate the common parts such that archs only worry about the
stack switch.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>

After the last architecture switched to generic hard irqs the config
options HAVE_GENERIC_HARDIRQS & GENERIC_HARDIRQS and the related code
for !CONFIG_GENERIC_HARDIRQS can be removed.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

In some cases, free_irq_cpu_rmap() is called while holding a lock (eg
rtnl).  This can lead to deadlocks, because it invokes
flush_scheduled_work() which ends up waiting for whole system workqueue
to flush, but some pending works might try to acquire the lock we are
already holding.

This commit uses reference-counting to replace
irq_run_affinity_notifiers().  It also removes
irq_run_affinity_notifiers() altogether.

[akpm@linux-foundation.org: eliminate free_cpu_rmap, rename cpu_rmap_reclaim() to cpu_rmap_release(), propagate kref_put() retval from cpu_rmap_put()]
Signed-off-by: NDavid Decotigny <decot@googlers.com>
Reviewed-by: NBen Hutchings <bhutchings@solarflare.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Acked-by: NAmir Vadai <amirv@mellanox.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The can_stop_idle_tick() function complains if a softirq vector is
raised too late in the idle-entry process, presumably in order to
prevent dangling softirq invocations from being delayed across the
full idle period, which might be indefinitely long -- and if softirq
was asserted any later than the call to this function, such a delay
might well happen.

However, RCU needs to be able to use softirq to stop idle entry in
order to be able to drain RCU callbacks from the current CPU, which in
turn enables faster entry into dyntick-idle mode, which in turn reduces
power consumption.  Because RCU takes this action at a well-defined
point in the idle-entry path, it is safe for RCU to take this approach.

This commit therefore silences the error message that is sometimes
produced when the going-idle CPU suddenly finds that it has an RCU_SOFTIRQ
to process.  The error message will continue to be issued for other
softirq vectors.
Reported-by: NSedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: NSedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>

The IRQF_SAMPLE_RANDOM flag is finally gone from the kernel tree, only
three years late.  :-)
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

exit_irq_thread() and task->irq_thread are needed to handle the unexpected
(and unlikely) exit of irq-thread.

We can use task_work instead and make this all private to
kernel/irq/manage.c, cleanup plus micro-optimization.

1. rename exit_irq_thread() to irq_thread_dtor(), make it
   static, and move it up before irq_thread().

2. change irq_thread() to do task_work_add(irq_thread_dtor)
   at the start and task_work_cancel() before return.

   tracehook_notify_resume() can never play with kthreads,
   only do_exit()->exit_task_work() can call the callback
   and this is what we want.

3. remove task_struct->irq_thread and the special hook
   in do_exit().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alexander Gordeev <agordeev@redhat.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Smith <dsmith@redhat.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

There is no need to have flags as unsigned long. Make it unsigned int
and put it together with irq so it does not waste space on 64 bit.
Make irq unsigned int while at it.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Remove all #inclusions of asm/system.h preparatory to splitting and killing
it.  Performed with the following command:

perl -p -i -e 's!^#\s*include\s*<asm/system[.]h>.*\n!!' `grep -Irl '^#\s*include\s*<asm/system[.]h>' *`
Signed-off-by: NDavid Howells <dhowells@redhat.com>

The __raise_softirq_irqoff() contains a tracepoint. As tracepoints in headers
can cause issues, and not to mention, bloats the kernel when they are
in a static inline, it is best to move the function that contains the
tracepoint out of the header and into softirq.c.

Link: http://lkml.kernel.org/r/20120118120711.GB14863@elte.huSuggested-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

This adds a mechanism to resume selected IRQs during syscore_resume
instead of dpm_resume_noirq.

Under Xen we need to resume IRQs associated with IPIs early enough
that the resched IPI is unmasked and we can therefore schedule
ourselves out of the stop_machine where the suspend/resume takes
place.

This issue was introduced by 676dc3cf "xen: Use IRQF_FORCE_RESUME".
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Jeremy Fitzhardinge <Jeremy.Fitzhardinge@citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Link: http://lkml.kernel.org/r/1318713254.11016.52.camel@dagon.hellion.org.uk
Cc: stable@kernel.org (at least to 2.6.32.y)
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

As request_percpu_irq() doesn't allow for a percpu interrupt to have
its type configured (it is generally impossible to configure it on all
CPUs at once), add a 'type' argument to enable_percpu_irq().

This allows some low-level, board specific init code to be switched to
a generic API.

[ tglx: Added WARN_ON argument ]
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Cc: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The ARM GIC interrupt controller offers per CPU interrupts (PPIs),
which are usually used to connect local timers to each core. Each CPU
has its own private interface to the GIC, and only sees the PPIs that
are directly connect to it.

While these timers are separate devices and have a separate interrupt
line to a core, they all use the same IRQ number.

For these devices, request_irq() is not the right API as it assumes
that an IRQ number is visible by a number of CPUs (through the
affinity setting), but makes it very awkward to express that an IRQ
number can be handled by all CPUs, and yet be a different interrupt
line on each CPU, requiring a different dev_id cookie to be passed
back to the handler.

The *_percpu_irq() functions is designed to overcome these
limitations, by providing a per-cpu dev_id vector:

int request_percpu_irq(unsigned int irq, irq_handler_t handler,
		   const char *devname, void __percpu *percpu_dev_id);
void free_percpu_irq(unsigned int, void __percpu *);
int setup_percpu_irq(unsigned int irq, struct irqaction *new);
void remove_percpu_irq(unsigned int irq, struct irqaction *act);
void enable_percpu_irq(unsigned int irq);
void disable_percpu_irq(unsigned int irq);

The API has a number of limitations:
- no interrupt sharing
- no threading
- common handler across all the CPUs

Once the interrupt is requested using setup_percpu_irq() or
request_percpu_irq(), it must be enabled by each core that wishes its
local interrupt to be delivered.

Based on an initial patch by Thomas Gleixner.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1316793788-14500-2-git-send-email-marc.zyngier@arm.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: NArun Sharma <asharma@fb.com>
Reviewed-by: NEric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit a26ac245(rcu: move TREE_RCU from softirq to kthread)
introduced performance regression. In an AIM7 test, this commit degraded
performance by about 40%.

The commit runs rcu callbacks in a kthread instead of softirq. We observed
high rate of context switch which is caused by this. Out test system has
64 CPUs and HZ is 1000, so we saw more than 64k context switch per second
which is caused by RCU's per-CPU kthread.  A trace showed that most of
the time the RCU per-CPU kthread doesn't actually handle any callbacks,
but instead just does a very small amount of work handling grace periods.
This means that RCU's per-CPU kthreads are making the scheduler do quite
a bit of work in order to allow a very small amount of RCU-related
processing to be done.

Alex Shi's analysis determined that this slowdown is due to lock
contention within the scheduler.  Unfortunately, as Peter Zijlstra points
out, the scheduler's real-time semantics require global action, which
means that this contention is inherent in real-time scheduling.  (Yes,
perhaps someone will come up with a workaround -- otherwise, -rt is not
going to do well on large SMP systems -- but this patch will work around
this issue in the meantime.  And "the meantime" might well be forever.)

This patch therefore re-introduces softirq processing to RCU, but only
for core RCU work.  RCU callbacks are still executed in kthread context,
so that only a small amount of RCU work runs in softirq context in the
common case.  This should minimize ksoftirqd execution, allowing us to
skip boosting of ksoftirqd for CONFIG_RCU_BOOST=y kernels.
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
Tested-by: N"Alex,Shi" <alex.shi@intel.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>

If RCU priority boosting is to be meaningful, callback invocation must
be boosted in addition to preempted RCU readers.  Otherwise, in presence
of CPU real-time threads, the grace period ends, but the callbacks don't
get invoked.  If the callbacks don't get invoked, the associated memory
doesn't get freed, so the system is still subject to OOM.

But it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit
moves the callback invocations to a kthread, which can be boosted easily.

Also add comments and properly synchronized all accesses to
rcu_cpu_kthread_task, as suggested by Lai Jiangshan.
Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>

Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>

Missed that one in the big compat remval patch
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Add a commandline parameter "threadirqs" which forces all interrupts except
those marked IRQF_NO_THREAD to run threaded. That's mostly a debug option to
allow retrieving better debug data from crashing interrupt handlers. If
"threadirqs" is not enabled on the kernel command line, then there is no
impact in the interrupt hotpath.

Architecture code needs to select CONFIG_IRQ_FORCED_THREADING after
marking the interrupts which cant be threaded IRQF_NO_THREAD. All
interrupts which have IRQF_TIMER set are implict marked
IRQF_NO_THREAD. Also all PER_CPU interrupts are excluded.

Forced threading hard interrupts also forces all soft interrupt
handling into thread context.

When enabled it might slow down things a bit, but for debugging problems in
interrupt code it's a reasonable penalty as it does not immediately
crash and burn the machine when an interrupt handler is buggy.

Some test results on a Core2Duo machine:

Cache cold run of:
 # time git grep irq_desc

      non-threaded       threaded
 real 1m18.741s          1m19.061s
 user 0m1.874s           0m1.757s
 sys  0m5.843s           0m5.427s

 # iperf -c server
non-threaded
[  3]  0.0-10.0 sec  1.09 GBytes   933 Mbits/sec
[  3]  0.0-10.0 sec  1.09 GBytes   934 Mbits/sec
[  3]  0.0-10.0 sec  1.09 GBytes   933 Mbits/sec
threaded
[  3]  0.0-10.0 sec  1.09 GBytes   939 Mbits/sec
[  3]  0.0-10.0 sec  1.09 GBytes   934 Mbits/sec
[  3]  0.0-10.0 sec  1.09 GBytes   937 Mbits/sec
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20110223234956.772668648@linutronix.de>

Some low level interrupts cannot be threaded even when we force thread
all interrupt handlers. Add a flag to annotate such interrupts. Add
all timer interrupts to this category by default.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20110223234956.578893460@linutronix.de>

For level type interrupts we need to track how many threads are on
flight to avoid useless interrupt storms when not all thread handlers
have finished yet. Keep track of the woken threads and only unmask
when there are no more threads in flight.

Yes, I'm lazy and using a bitfield. But not only because I'm lazy, the
main reason is that it's way simpler than using a refcount. A refcount
based solution would need to keep track of various things like
crashing the irq thread, spurious interrupts coming in,
disables/enables, free_irq() and some more. The bitfield keeps the
tracking simple and makes things just work. It's also nicely confined
to the thread code pathes and does not require additional checks all
over the place.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20110223234956.388095876@linutronix.de>

All archs implement show_interrupts() in more or less the same
way. That's tons of duplicated code with different bugs with no
value. Implement a generic version and deprecate show_interrupts()

Unfortunately we need some ifdeffery for !GENERIC_HARDIRQ archs.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Soleley used in core code.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The irq namespace has become quite convoluted. My bad.  Clean it up
and deprecate the old functions. All new functions follow the scheme:

irq number based:
    irq_set/get/xxx/_xxx(unsigned int irq, ...)

irq_data based:
	 irq_data_set/get/xxx/_xxx(struct irq_data *d, ....)

irq_desc based:
	 irq_desc_get_xxx(struct irq_desc *desc)
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Xen needs to reenable interrupts which are marked IRQF_NO_SUSPEND in the
resume path. Add a flag to force the reenabling in the resume code.
Tested-and-acked-by: NIan Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>