The primary aim of this patchset is to remove maintenances problems caused by
the irq infrastructure.  The two big issues I address are an artificially
small cap on the number of irqs, and that MSI assumes vector == irq.  My
primary focus is on x86_64 but I have touched other architectures where
necessary to keep them from breaking.

- To increase the number of irqs I modify the code to look at the (cpu,
  vector) pair instead of just looking at the vector.

  With a large number of irqs available systems with a large irq count no
  longer need to compress their irq numbers to fit.  Removing a lot of brittle
  special cases.

  For acpi guys the result is that irq == gsi.

- Addressing the fact that MSI assumes irq == vector takes a few more
  patches.  But suffice it to say when I am done none of the generic irq code
  even knows what a vector is.

In quick testing on a large Unisys x86_64 machine we stumbled over at least
one driver that assumed that NR_IRQS could always fit into an 8 bit number.
This driver is clearly buggy today.  But this has become a class of bugs that
it is now much easier to hit.

This patch:

This is a minor space optimization.  In practice I don't think this has any
affect because of our alignment constraints and the other fields but there is
not point in chewing up an uncessary word and since we already read the flag
field this should improve the cache hit ratio of the irq handler.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rajesh Shah <rajesh.shah@intel.com>
Cc: Andi Kleen <ak@muc.de>
Cc: "Protasevich, Natalie" <Natalie.Protasevich@UNISYS.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Consolidation: remove the pending_irq_cpumask[NR_IRQS] array and move it into
the irq_desc[NR_IRQS].pending_mask field.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Cleanup: remove irq_desc_t use from the generic IRQ code, and mark it
obsolete.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Cleanup: remove irq_descp() - explicit use of irq_desc[] is shorter and more
readable.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch-queue improves the generic IRQ layer to be truly generic, by adding
various abstractions and features to it, without impacting existing
functionality.

While the queue can be best described as "fix and improve everything in the
generic IRQ layer that we could think of", and thus it consists of many
smaller features and lots of cleanups, the one feature that stands out most is
the new 'irq chip' abstraction.

The irq-chip abstraction is about describing and coding and IRQ controller
driver by mapping its raw hardware capabilities [and quirks, if needed] in a
straightforward way, without having to think about "IRQ flow"
(level/edge/etc.) type of details.

This stands in contrast with the current 'irq-type' model of genirq
architectures, which 'mixes' raw hardware capabilities with 'flow' details.
The patchset supports both types of irq controller designs at once, and
converts i386 and x86_64 to the new irq-chip design.

As a bonus side-effect of the irq-chip approach, chained interrupt controllers
(master/slave PIC constructs, etc.) are now supported by design as well.

The end result of this patchset intends to be simpler architecture-level code
and more consolidation between architectures.

We reused many bits of code and many concepts from Russell King's ARM IRQ
layer, the merging of which was one of the motivations for this patchset.

This patch:

rename desc->handler to desc->chip.

Originally i did not want to do this, because it's a big patch.  But having
both "desc->handler", "desc->handle_irq" and "action->handler" caused a
large degree of confusion and made the code appear alot less clean than it
truly is.

I have also attempted a dual approach as well by introducing a
desc->chip alias - but that just wasnt robust enough and broke
frequently.

So lets get over with this quickly.  The conversion was done automatically
via scripts and converts all the code in the kernel.

This renaming patch is the first one amongst the patches, so that the
remaining patches can stay flexible and can be merged and split up
without having some big monolithic patch act as a merge barrier.

[akpm@osdl.org: build fix]
[akpm@osdl.org: another build fix]
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

If you get to that point in the code it means that desc->move_irq is set,
pending_irq_cpumask[irq] and cpu_online_map should have a value.  Still
pretty good chance anding those two you'll still have a value.  So these
two branch predictors should be inverted.
Signed-off-by: NDaniel Walker <dwalker@mvista.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This fix prevents re-disabling and enabling of a previously disabled
interrupt.  On an SMP system with irq balancing enabled; If an interrupt is
disabled from within its own interrupt context with disable_irq_nosync and is
also earmarked for processor migration, the interrupt is blindly moved to the
other processor and enabled without regard for its current "enabled" state.
If there is an interrupt pending, it will unexpectedly invoke the irq handler
on the new irq owning processor (even though the irq was previously disabled)

The more intuitive fix would be to invoke disable_irq_nosync and
enable_irq, but since we already have the desc->lock from __do_IRQ, we
cannot call them directly.  Instead we can use the same logic to disable
and enable found in disable_irq_nosync and enable_irq, with regards to the
desc->depth.

This now prevents a disabled interrupt from being re-disabled, and more
importantly prevents a disabled interrupt from being incorrectly enabled on
a different processor.
Signed-off-by: NBryan Holty <lgeek@frontiernet.net>
Cc: Andi Kleen <ak@muc.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Uninline some massive IRQ migration functions.  Put them in the new
kernel/irq/migration.c.

Cc: Andi Kleen <ak@muc.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>