linux-toradex.git/kernel/irq/migration.c, branch v2.6.36-rc7

genirq: Convert irq_desc.lock to raw_spinlock

2009-12-14T22:55:33+00:00

Convert locks which cannot be sleeping locks in preempt-rt to
raw_spinlocks.

Signed-off-by: Thomas Gleixner 
Acked-by: Peter Zijlstra 
Acked-by: Ingo Molnar

genirq: Delegate irq affinity setting to the irq thread

2009-07-21T12:35:07+00:00

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: Thomas Gleixner 
LKML-Reference:

irq: only update affinity if ->set_affinity() is sucessfull

2009-04-28T10:21:16+00:00

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: Yinghai Lu 
Cc: Andrew Morton 
Cc: Suresh Siddha 
Cc: "Eric W. Biederman" 
Cc: Rusty Russell 
LKML-Reference: <49F65509.60307@kernel.org>
Signed-off-by: Ingo Molnar

cpumask: update irq_desc to use cpumask_var_t

2009-01-11T18:12:46+00:00

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: Mike Travis 
Cc: Chris Wright 
Cc: Jeremy Fitzhardinge 
Cc: KOSAKI Motohiro 
Cc: Venkatesh Pallipadi 
Cc: virtualization@lists.osdl.org
Cc: xen-devel@lists.xensource.com
Cc: Yinghai Lu

cpumask: make irq_set_affinity() take a const struct cpumask

2008-12-13T10:50:26+00:00

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: Rusty Russell 
Signed-off-by: Mike Travis 
Reviewed-by: Grant Grundler 
Acked-by: Ingo Molnar 
Cc: ralf@linux-mips.org
Cc: grundler@parisc-linux.org
Cc: jeremy@xensource.com
Cc: KOSAKI Motohiro

genirq: keep affinities set from userspace across free/request_irq()

2008-11-09T21:23:49+00:00

Impact: preserve user-modified affinities on interrupts

Kumar Galak noticed that commit
18404756765c713a0be4eb1082920c04822ce588 (genirq: Expose default irq
affinity mask (take 3))

overrides an already set affinity setting across a free /
request_irq(). Happens e.g. with ifdown/ifup of a network device.

Change the logic to mark the affinities as set and keep them
intact. This also fixes the unlocked access to irq_desc in
irq_select_affinity() when called from irq_affinity_proc_write()

Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar

generic: sparse irqs: use irq_desc() together with dyn_array, instead of irq_desc[]

2008-10-16T14:52:29+00:00

add CONFIG_HAVE_SPARSE_IRQ to for use condensed array.
Get rid of irq_desc[] array assumptions.

Preallocate 32 irq_desc, and irq_desc() will try to get more.

( No change in functionality is expected anywhere, except the odd build
  failure where we missed a code site or where a crossing commit itroduces
  new irq_desc[] usage. )

v2: according to Eric, change get_irq_desc() to irq_desc()

Signed-off-by: Yinghai Lu 
Signed-off-by: Ingo Molnar

[PATCH] genirq: Mask irqs when migrating them.

2007-02-26T18:34:08+00:00

move_native_irqs tries to do the right thing when migrating irqs
by disabling them.  However disabling them is a software logical
thing, not a hardware thing.  This has always been a little flaky
and after Ingo's latest round of changes it is guaranteed to not
mask the apic.

So this patch fixes move_native_irq to directly call the mask and
unmask chip methods to guarantee that we mask the irq when we
are migrating it.  We must do this as it is required by
all code that call into the path.

Since we don't know the masked status when IRQ_DISABLED is
set so we will not be able to restore it.   The patch makes the code
just give up and trying again the next time this routing is called.

Signed-off-by: Eric W. Biederman 
Acked-by: Suresh Siddha 
Signed-off-by: Linus Torvalds

[PATCH] genirq: irq: add moved_masked_irq

2006-10-04T14:55:26+00:00

Currently move_native_irq disables and renables the irq we are migrating to
ensure we don't take that irq when we are actually doing the migration
operation.  Disabling the irq needs to happen but sometimes doing the work is
move_native_irq is too late.

On x86 with ioapics the irq move sequences needs to be:
edge_triggered:
  mask irq.
  move irq.
  unmask irq.
  ack irq.
level_triggered:
  mask irq.
  ack irq.
  move irq.
  unmask irq.

We can easily perform the edge triggered sequence, with the current defintion
of move_native_irq.  However the level triggered case does not map well.  For
that I have added move_masked_irq, to allow me to disable the irqs around both
the ack and the move.

Q: Why have we not seen this problem earlier?

A: The only symptom I have been able to reproduce is that if we change
   the vector before acknowleding an irq the wrong irq is acknowledged.
   Since we currently are not reprogramming the irq vector during
   migration no problems show up.

   We have to mask the irq before we acknowledge the irq or else we could
   hit a window where an irq is asserted just before we acknowledge it.

   Edge triggered irqs do not have this problem because acknowledgements
   do not propogate in the same way.

Signed-off-by: Eric W. Biederman 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: Benjamin Herrenschmidt 
Cc: Rajesh Shah 
Cc: Andi Kleen 
Cc: "Protasevich, Natalie" 
Cc: "Luck, Tony" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] genirq: irq: convert the move_irq flag from a 32bit word to a single bit

2006-10-04T14:55:26+00:00

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: Eric W. Biederman 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: Benjamin Herrenschmidt 
Cc: Rajesh Shah 
Cc: Andi Kleen 
Cc: "Protasevich, Natalie" 
Cc: "Luck, Tony" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds