Network folks reported that directing all MSI-X vectors of their multi
queue NICs to a single core can cause interrupt stack overflows when
enough interrupts fire at the same time.

This is caused by the fact that we run interrupt handlers by default
with interrupts enabled unless the driver reuqests the interrupt with
the IRQF_DISABLED set. The NIC handlers do not set this flag, so
simultaneous interrupts can nest unlimited and cause the stack
overflow.

The only safe counter measure is to run the interrupt handlers with
interrupts disabled. We can't switch to this mode in general right
now, but it is safe to do so for MSI interrupts.

Force IRQF_DISABLED for MSI interrupt handlers.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@osdl.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: David Miller <davem@davemloft.net>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: stable@kernel.org

can_request_irq() accesses and dereferences irq_desc->action w/o
holding irq_desc->lock. So action can be freed on another CPU before
it's dereferenced. Unlikely, but ...

Protect it with desc->lock.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Lars-Peter pointed out that the oneshot threaded interrupt handler
code has the following race:

 CPU0                            CPU1
 hande_level_irq(irq X)
   mask_ack_irq(irq X)
   handle_IRQ_event(irq X)
     wake_up(thread_handler)
                                 thread handler(irq X) runs
                                 finalize_oneshot(irq X)
				  does not unmask due to 
				  !(desc->status & IRQ_MASKED)

 return from irq
 does not unmask due to
 (desc->status & IRQ_ONESHOT)
  				  
This leaves the interrupt line masked forever. 

The reason for this is the inconsistent handling of the IRQ_MASKED
flag. Instead of setting it in the mask function the oneshot support
sets the flag after waking up the irq thread.

The solution for this is to set/clear the IRQ_MASKED status whenever
we mask/unmask an interrupt line. That's the easy part, but that
cleanup opens another race:

 CPU0                            CPU1
 hande_level_irq(irq)
   mask_ack_irq(irq)
   handle_IRQ_event(irq)
     wake_up(thread_handler)
                                 thread handler(irq) runs
                                 finalize_oneshot_irq(irq)
				  unmask(irq)
     irq triggers again
     handle_level_irq(irq)
       mask_ack_irq(irq)
     return from irq due to IRQ_INPROGRESS				  

 return from irq
 does not unmask due to
 (desc->status & IRQ_ONESHOT)

This requires that we synchronize finalize_oneshot_irq() with the
primary handler. If IRQ_INPROGESS is set we wait until the primary
handler on the other CPU has returned before unmasking the interrupt
line again.

We probably have never seen that problem because it does not happen on
UP and on SMP the irqbalancer protects us by pinning the primary
handler and the thread to the same CPU.
Reported-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: stable@kernel.org

Convert locks which cannot be sleeping locks in preempt-rt to
raw_spinlocks.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Acked-by: NIngo Molnar <mingo@elte.hu>

The wake_up_process() of the new irq thread in __setup_irq() is too
early as the irqaction is not yet fully initialized especially
action->irq is not yet set. The interrupt thread might dereference the
wrong irq descriptor.

Move the wakeup after the action is installed and action->irq has been
set.
Reported-by: NMichael Buesch <mb@bu3sch.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NMichael Buesch <mb@bu3sch.de>

Interrupt chips which are behind a slow bus (i2c, spi ...) and
demultiplex other interrupt sources need to run their interrupt
handler in a thread. 

The demultiplexed interrupt handlers need to run in thread context as
well and need to finish before the demux handler thread can reenable
the interrupt line. So the easiest way is to run the sub device
handlers in the context of the demultiplexing handler thread.

To avoid that a separate thread is created for the subdevices the
function set_nested_irq_thread() is provided which sets the
IRQ_NESTED_THREAD flag in the interrupt descriptor.

A driver which calls request_threaded_irq() must not be aware of the
fact that the threaded handler is called in the context of the
demultiplexing handler thread. The setup code checks the
IRQ_NESTED_THREAD flag which was set from the irq chip setup code and
does not setup a separate thread for the interrupt. The primary
function which is provided by the device driver is replaced by an
internal dummy function which warns when it is called.

For the demultiplexing handler a helper function handle_nested_irq()
is provided which calls the demux interrupt thread function in the
context of the caller and does the proper interrupt accounting and
takes the interrupt disabled status of the demultiplexed subdevice
into account.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Trilok Soni <soni.trilok@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Brian Swetland <swetland@google.com>
Cc: Joonyoung Shim <jy0922.shim@samsung.com>
Cc: m.szyprowski@samsung.com
Cc: t.fujak@samsung.com
Cc: kyungmin.park@samsung.com,
Cc: David Brownell <david-b@pacbell.net>
Cc: Daniel Ribeiro <drwyrm@gmail.com>
Cc: arve@android.com
Cc: Barry Song <21cnbao@gmail.com>

Some interrupt chips are connected to a "slow" bus (i2c, spi ...). The
bus access needs to sleep and therefor cannot be called in atomic
contexts.

Some of the generic interrupt management functions like disable_irq(),
enable_irq() ... call interrupt chip functions with the irq_desc->lock
held and interrupts disabled. This does not work for such devices.

Provide a separate synchronization mechanism for such interrupt
chips. The irq_chip structure is extended by two optional functions
(bus_lock and bus_sync_and_unlock).

The idea is to serialize the bus access for those operations in the
core code so that drivers which are behind that bus operated interrupt
controller do not have to worry about it and just can use the normal
interfaces. To achieve this we add two function pointers to the
irq_chip: bus_lock and bus_sync_unlock.

bus_lock() is called to serialize access to the interrupt controller
bus.

Now the core code can issue chip->mask/unmask ... commands without
changing the fast path code at all. The chip implementation merily
stores that information in a chip private data structure and
returns. No bus interaction as these functions are called from atomic
context.

After that bus_sync_unlock() is called outside the atomic context. Now
the chip implementation issues the bus commands, waits for completion
and unlocks the interrupt controller bus.

The irq_chip implementation as pseudo code:

struct irq_chip_data {
       struct mutex   mutex;
       unsigned int   irq_offset;
       unsigned long  mask;
       unsigned long  mask_status;
}

static void bus_lock(unsigned int irq)
{
        struct irq_chip_data *data = get_irq_desc_chip_data(irq);

        mutex_lock(&data->mutex);
}

static void mask(unsigned int irq)
{
        struct irq_chip_data *data = get_irq_desc_chip_data(irq);

        irq -= data->irq_offset;
        data->mask |= (1 << irq);
}

static void unmask(unsigned int irq)
{
        struct irq_chip_data *data = get_irq_desc_chip_data(irq);

        irq -= data->irq_offset;
        data->mask &= ~(1 << irq);
}

static void bus_sync_unlock(unsigned int irq)
{
        struct irq_chip_data *data = get_irq_desc_chip_data(irq);

        if (data->mask != data->mask_status) {
                do_bus_magic_to_set_mask(data->mask);
                data->mask_status = data->mask;
        }
        mutex_unlock(&data->mutex);
}

The device drivers can use request_threaded_irq, free_irq, disable_irq
and enable_irq as usual with the only restriction that the calls need
to come from non atomic context.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Trilok Soni <soni.trilok@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Brian Swetland <swetland@google.com>
Cc: Joonyoung Shim <jy0922.shim@samsung.com>
Cc: m.szyprowski@samsung.com
Cc: t.fujak@samsung.com
Cc: kyungmin.park@samsung.com,
Cc: David Brownell <david-b@pacbell.net>
Cc: Daniel Ribeiro <drwyrm@gmail.com>
Cc: arve@android.com
Cc: Barry Song <21cnbao@gmail.com>

For threaded interrupt handlers we expect the hard interrupt handler
part to mask the interrupt on the originating device. The interrupt
line itself is reenabled after the hard interrupt handler has
executed.

This requires access to the originating device from hard interrupt
context which is not always possible. There are devices which can only
be accessed via a bus (i2c, spi, ...). The bus access requires thread
context. For such devices we need to keep the interrupt line masked
until the threaded handler has executed.

Add a new flag IRQF_ONESHOT which allows drivers to request that the
interrupt is not unmasked after the hard interrupt context handler has
been executed and the thread has been woken. The interrupt line is
unmasked after the thread handler function has been executed.

Note that for now IRQF_ONESHOT cannot be used with IRQF_SHARED to
avoid complex accounting mechanisms.

For oneshot interrupts the primary handler simply returns
IRQ_WAKE_THREAD and does nothing else. A generic implementation
irq_default_primary_handler() is provided to avoid useless copies all
over the place. It is automatically installed when
request_threaded_irq() is called with handler=NULL and
thread_fn!=NULL.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Trilok Soni <soni.trilok@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Brian Swetland <swetland@google.com>
Cc: Joonyoung Shim <jy0922.shim@samsung.com>
Cc: m.szyprowski@samsung.com
Cc: t.fujak@samsung.com
Cc: kyungmin.park@samsung.com,
Cc: David Brownell <david-b@pacbell.net>
Cc: Daniel Ribeiro <drwyrm@gmail.com>
Cc: arve@android.com
Cc: Barry Song <21cnbao@gmail.com>

free_irq() can remove an irqaction while the corresponding interrupt
is in progress, but free_irq() sets action->thread to NULL
unconditionally, which might lead to a NULL pointer dereference in
handle_IRQ_event() when the hard interrupt context tries to wake up
the handler thread.

Prevent this by moving the thread stop after synchronize_irq(). No
need to set action->thread to NULL either as action is going to be
freed anyway.

This fixes a boot crash reported against preempt-rt which uses the
mainline irq threads code to implement full irq threading.

[ tglx: removed local irqthread variable ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Since genirq: Delegate irq affinity setting to the irq thread
(591d2fb0) compilation with
CONFIG_SMP=n fails with following error:

/usr/src/linux-2.6/kernel/irq/manage.c:
   In function 'irq_thread_check_affinity':
/usr/src/linux-2.6/kernel/irq/manage.c:475:
   error: 'struct irq_desc' has no member named 'affinity'
make[4]: *** [kernel/irq/manage.o] Error 1

That commit adds a new function irq_thread_check_affinity() which
uses struct irq_desc.affinity which is only available for CONFIG_SMP=y.
Move that function under #ifdef CONFIG_SMP.

[ tglx@brownpaperbag: compile and boot tested on UP and SMP ]
Signed-off-by: NBruno Premont <bonbons@linux-vserver.org>
LKML-Reference: <20090722222232.2eb3e1c4@neptune.home>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

irq_set_thread_affinity() calls set_cpus_allowed_ptr() which might
sleep, but irq_set_thread_affinity() is called with desc->lock held
and can be called from hard interrupt context as well. The code has
another bug as it does not hold a ref on the task struct as required
by set_cpus_allowed_ptr().

Just set the IRQTF_AFFINITY bit in action->thread_flags. The next time
the thread runs it migrates itself. Solves all of the above problems
nicely.

Add kerneldoc to irq_set_thread_affinity() while at it.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
LKML-Reference: <new-submission>

Trying to implement a driver to use threaded irqs, I was confused when the 
return value to use that was described in the comment above 
request_threaded_irq was not defined.

Turns out that the enum is IRQ_WAKE_THREAD where as the comment said 
IRQ_THREAD_WAKE.

[Impact: do not confuse developers with wrong comments ]
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
LKML-Reference: <alpine.DEB.2.00.0905121431020.13338@gandalf.stny.rr.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

irq_set_affinity() and move_masked_irq() try to assign affinity
before calling chip set_affinity(). Some archs are assigning it
in ->set_affinity() again.

We do something like:

 cpumask_cpy(desc->affinity, mask);
 desc->chip->set_affinity(mask);

But in the failure path, affinity should not be touched - otherwise
we'll end up with a different affinity mask despite the failure to
migrate the IRQ.

So try to update the afffinity only if set_affinity returns with 0.
Also call irq_set_thread_affinity accordingly.

v2: update after "irq, x86: Remove IRQ_DISABLED check in process context IRQ move"
v3: according to Ingo, change set_affinity() in irq_chip should return int.
v4: update comments by removing moving irq_desc code.

[ Impact: fix /proc/irq/*/smp_affinity setting corner case bug ]
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
LKML-Reference: <49F65509.60307@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When requesting an IRQ, the DEBUG_SHIRQ code executes a fake IRQ just to make
sure the driver is ready to receive an IRQ immediately.  The problem was that
this fake IRQ was being executed even if interrupt line failed to be allocated
by __setup_irq.
Signed-off-by: NLuis Henriques <henrix@sapo.pt>
LKML-Reference: <20090401170635.GA4392@hades.domain.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
[ fixed bug pointed out by a warning reported by Stephen Rothwell ]
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

As discussed in the thread here:

  http://marc.info/?l=linux-kernel&m=123964468521142&w=2

Eric W. Biederman observed:

> It looks like some additional bugs have slipped in since last I looked.
>
> set_irq_affinity does this:
> ifdef CONFIG_GENERIC_PENDING_IRQ
>        if (desc->status & IRQ_MOVE_PCNTXT || desc->status & IRQ_DISABLED) {
>                cpumask_copy(desc->affinity, cpumask);
>                desc->chip->set_affinity(irq, cpumask);
>        } else {
>                desc->status |= IRQ_MOVE_PENDING;
>                cpumask_copy(desc->pending_mask, cpumask);
>        }
> #else
>
> That IRQ_DISABLED case is a software state and as such it has nothing to
> do with how safe it is to move an irq in process context.

[...]

>
> The only reason we migrate MSIs in interrupt context today is that there
> wasn't infrastructure for support migration both in interrupt context
> and outside of it.

Yes. The idea here was to force the MSI migration to happen in process
context. One of the patches in the series did

        disable_irq(dev->irq);
        irq_set_affinity(dev->irq, cpumask_of(dev->cpu));
        enable_irq(dev->irq);

with the above patch adding irq/manage code check for interrupt disabled
and moving the interrupt in process context.

IIRC, there was no IRQ_MOVE_PCNTXT when we were developing this HPET
code and we ended up having this ugly hack. IRQ_MOVE_PCNTXT was there
when we eventually submitted the patch upstream. But, looks like I did a
blind rebasing instead of using IRQ_MOVE_PCNTXT in hpet MSI code.

Below patch fixes this. i.e., revert commit 932775a4
and add PCNTXT to HPET MSI setup. Also removes copying of desc->affinity
in generic code as set_affinity routines are doing it internally.
Reported-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Li Shaohua" <shaohua.li@intel.com>
Cc: Gary Hade <garyhade@us.ibm.com>
Cc: "lcm@us.ibm.com" <lcm@us.ibm.com>
Cc: suresh.b.siddha@intel.com
LKML-Reference: <20090413222058.GB8211@linux-os.sc.intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Introduce helper functions allowing us to prevent device drivers from
getting any interrupts (without disabling interrupts on the CPU)
during suspend (or hibernation) and to make them start to receive
interrupts again during the subsequent resume.  These functions make it
possible to keep timer interrupts enabled while the "late" suspend and
"early" resume callbacks provided by device drivers are being
executed.  In turn, this allows device drivers' "late" suspend and
"early" resume callbacks to sleep, execute ACPI callbacks etc.

The functions introduced here will be used to rework the handling of
interrupts during suspend (hibernation) and resume.  Namely,
interrupts will only be disabled on the CPU right before suspending
sysdevs, while device drivers will be prevented from receiving
interrupts, with the help of the new helper function, before their
"late" suspend callbacks run (and analogously during resume).
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NIngo Molnar <mingo@elte.hu>

Delta patch to address the review comments.

      - Implement warning when IRQ_WAKE_THREAD is requested and no
        thread handler installed
      - coding style fixes
Pointed-out-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Add support for threaded interrupt handlers:

A device driver can request that its main interrupt handler runs in a
thread. To achive this the device driver requests the interrupt with
request_threaded_irq() and provides additionally to the handler a
thread function. The handler function is called in hard interrupt
context and needs to check whether the interrupt originated from the
device. If the interrupt originated from the device then the handler
can either return IRQ_HANDLED or IRQ_WAKE_THREAD. IRQ_HANDLED is
returned when no further action is required. IRQ_WAKE_THREAD causes
the genirq code to invoke the threaded (main) handler. When
IRQ_WAKE_THREAD is returned handler must have disabled the interrupt
on the device level. This is mandatory for shared interrupt handlers,
but we need to do it as well for obscure x86 hardware where disabling
an interrupt on the IO_APIC level redirects the interrupt to the
legacy PIC interrupt lines.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NIngo Molnar <mingo@elte.hu>

Impact: simplification
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NPeter Zijlstra <peterz@infradead.org>

Impact: cleanup

The code is only compiled if CONFIG_GENERIC_HARDIRQS=y so another
check for this define in the code is redundant. Remove it.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Export the setup_irq() and remove_irq() symbols.

I'd like to export these functions since I have timer
code that needs to use setup_irq() early on (too early
for request_irq()), and the same code can also be
compiled as a module.
Signed-off-by: NMagnus Damm <damm@igel.co.jp>
LKML-Reference: <20090312120559.2926.82371.sendpatchset@rx1.opensource.se>
[ changed to _GPL as these are special APIs deep inside the irq layer. ]
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Modify remove_irq() to match setup_irq().
Signed-off-by: NMagnus Damm <damm@igel.co.jp>
LKML-Reference: <20090312120551.2926.43942.sendpatchset@rx1.opensource.se>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: add new API

This patch adds a remove_irq() function for releasing
interrupts requested with setup_irq().

Without this patch we have no way of releasing such
interrupts since free_irq() today tries to kfree()
the irqaction passed with setup_irq().
Signed-off-by: NMagnus Damm <damm@igel.co.jp>
LKML-Reference: <20090312120542.2926.56609.sendpatchset@rx1.opensource.se>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

'p' stands for pointer - make it clear in setup_irq() and free_irq()
what kind of pointer it is.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Linus noticed that the 'pp' variable can be eliminated
altogether, and the loop can be cleaned up further.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

- separate out the loop from the actual freeing logic, this wins us
  two indentation levels allowing a number of followup prettifications

- turn the WARN_ON() into a more informative WARN().

- clean up the comments and the code flow some more

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

- make printk message git-greppable
- fix a few style details
Signed-off-by: NIngo Molnar <mingo@elte.hu>

request_irq() calls into proc code via __setup_irq() which is not safe
in an atomic context, so request_irq() can itself use the more
reliable GFP_KERNEL allocation for the action descriptor.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

While being at it make every occurrence of 'do_irq_select_affinity'
have the same signature in terms of signedness of the first argument.

Fix this sparse warning:
  kernel/irq/manage.c:112:5: warning: symbol 'do_irq_select_affinity' was not declared. Should it be static?

Also rename do_irq_select_affinity() to setup_affinity() - shorter name
and clearer naming.
Signed-off-by: NHannes Eder <hannes@hanneseder.net>
Acked-by: NMatthew Wilcox <matthew@wil.cx>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Move the initialization of irq_default_affinity to early_irq_init as
core_initcall is too late.

irq_default_affinity can be used in init_IRQ and potentially timer and
SMP init as well.  All of these happen before core_initcall.  Moving
the initialization to early_irq_init ensures that it is initialized
before it is used.
Signed-off-by: NDavid Daney <ddaney@caviumnetworks.com>
Acked-by: NMike Travis <travis@sgi.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In interrupt.h these functions are declared only if
CONFIG_GENERIC_HARDIRQS is set.  We should define them under identical
conditions.
Signed-off-by: NDavid Daney <ddaney@caviumnetworks.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Impact: reduce memory usage, use new cpumask API.

Replace the affinity and pending_masks with cpumask_var_t's.  This adds
to the significant size reduction done with the SPARSE_IRQS changes.

The added functions (init_alloc_desc_masks & init_copy_desc_masks) are
in the include file so they can be inlined (and optimized out for the
!CONFIG_CPUMASKS_OFFSTACK case.)  [Naming chosen to be consistent with
the other init*irq functions, as well as the backwards arg declaration
of "from, to" instead of the more common "to, from" standard.]

Includes a slight change to the declaration of struct irq_desc to embed
the pending_mask within ifdef(CONFIG_SMP) to be consistent with other
references, and some small changes to Xen.

Tested: sparse/non-sparse/cpumask_offstack/non-cpumask_offstack/nonuma/nosmp on x86_64
Signed-off-by: NMike Travis <travis@sgi.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: virtualization@lists.osdl.org
Cc: xen-devel@lists.xensource.com
Cc: Yinghai Lu <yhlu.kernel@gmail.com>

Impact: Reduce stack usage, use new cpumask API.  ALPHA mod!

Main change is that irq_default_affinity becomes a cpumask_var_t, so
treat it as a pointer (this effects alpha).
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

GCC has a bug with __weak alias functions: if the functions are in
the same compilation unit as their call site, GCC can decide to
inline them - and thus rob the linker of the opportunity to override
the weak alias with the real thing.

So move all the IRQ handling related __weak symbols to kernel/irq/chip.c.
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix boot crash if the kernel is built with certain GCC versions

GCC has a bug with __weak alias functions: if the functions are in
the same compilation unit as their call site, GCC can decide to
inline them - and thus rob the linker of the opportunity to override
the weak alias with the real thing.

This can lead to the boot crash reported by Kamalesh Babulal:

 ACPI: Core revision 20080926
 Setting APIC routing to flat
 BUG: unable to handle kernel NULL pointer dereference at
 0000000000000000
 IP: [<ffffffff8021f9a8>] add_pin_to_irq_cpu+0x14/0x74
 PGD 0
 Oops: 0000 [#1] SMP
 [...]

So move the arch_init_chip_data() function from handle.c to manage.c.
Reported-by: NKamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: change existing irq_chip API

Not much point with gentle transition here: the struct irq_chip's
setaffinity method signature needs to change.

Fortunately, not widely used code, but hits a few architectures.

Note: In irq_select_affinity() I save a temporary in by mangling
irq_desc[irq].affinity directly.  Ingo, does this break anything?

(Folded in fix from KOSAKI Motohiro)
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NMike Travis <travis@sgi.com>
Reviewed-by: NGrant Grundler <grundler@parisc-linux.org>
Acked-by: NIngo Molnar <mingo@redhat.com>
Cc: ralf@linux-mips.org
Cc: grundler@parisc-linux.org
Cc: jeremy@xensource.com
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

Impact: emit new warning

We periodically waste time tracking down problems from the genirq
framework not respecting IRQF_DISABLED for some shared IRQ cases.  Linus
views this as "will not fix", but we're still left with the bugs caused by
this misbehavior.

This patch adds a nag message in request_irq(), so that drivers can fix
their IRQ handlers to avoid this problem.

Note that developers will never see the relevant bugs when they run with
LOCKDEP, so it's no wonder these bugs are hard to find.  (That also means
LOCKDEP is overlooking some IRQ-related bugs involving IRQ handlers that
don't set IRQF_DISABLED...)
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix __irq_set_trigger() for IRQ_LEVEL

When recording the irq trigger type, let's also make sure
that IRQ_LEVEL gets set correctly.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Commit 0c5d1eb7 (genirq: record trigger
type) caused powerpc platforms that had no set_type() function in their
struct irq_chip to spew out warnings about "No set_type function for
IRQ...". This warning isn't necessarily justified though because the
generic powerpc platform code calls set_irq_type() (which in turn calls
__irq_set_trigger) with information from the device tree to establish
the interrupt mappings, regardless of whether the PIC can actually set
a type.

A platform's irq_chip might not have a set_type function for a variety
of reasons, for example: the platform may have the type essentially
hard-coded, or as in the case for Cell interrupts are just messages
past around that have no real concept of type, or the platform
could even have a virtual PIC as on the PS3.
Signed-off-by: NMark Nelson <markn@au1.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: build fix

fix build failure on UP.
Signed-off-by: NIngo Molnar <mingo@elte.hu>