linux-toradex.git/kernel/irq, branch v2.6.34.15

genirq: Fix race condition when stopping the irq thread

2013-01-16T21:45:01+00:00

commit 550acb19269d65f32e9ac4ddb26c2b2070e37f1c upstream.

In irq_wait_for_interrupt(), the should_stop member is verified before
setting the task's state to TASK_INTERRUPTIBLE and calling schedule().
In case kthread_stop sets should_stop and wakes up the process after
should_stop is checked by the irq thread but before the task's state
is changed, the irq thread might never exit:

kthread_stop                    irq_wait_for_interrupt
------------                    ----------------------

                                 ...
...                              while (!kthread_should_stop()) {
kthread->should_stop = 1;
wake_up_process(k);
wait_for_completion(&kthread->exited);
...
                                     set_current_state(TASK_INTERRUPTIBLE);

                                     ...

                                     schedule();
                                 }

Fix this by checking if the thread should stop after modifying the
task's state.

[ tglx: Simplified it a bit ]

Signed-off-by: Ido Yariv 
Link: http://lkml.kernel.org/r/1322740508-22640-1-git-send-email-ido@wizery.com
Signed-off-by: Thomas Gleixner 
Signed-off-by: Paul Gortmaker

random: remove rand_initialize_irq()

2012-08-17T19:36:09+00:00

commit c5857ccf293968348e5eb4ebedc68074de3dcda6 upstream.

With the new interrupt sampling system, we are no longer using the
timer_rand_state structure in the irq descriptor, so we can stop
initializing it now.

[ Merged in fixes from Sedat to find some last missing references to
  rand_initialize_irq() ]

Signed-off-by: "Theodore Ts'o" 
Signed-off-by: Sedat Dilek 
[PG: in .34 the irqdesc.h content is in irq.h instead.]
Signed-off-by: Paul Gortmaker

random: make 'add_interrupt_randomness()' do something sane

2012-08-17T19:36:05+00:00

commit 775f4b297b780601e61787b766f306ed3e1d23eb upstream.

We've been moving away from add_interrupt_randomness() for various
reasons: it's too expensive to do on every interrupt, and flooding the
CPU with interrupts could theoretically cause bogus floods of entropy
from a somewhat externally controllable source.

This solves both problems by limiting the actual randomness addition
to just once a second or after 64 interrupts, whicever comes first.
During that time, the interrupt cycle data is buffered up in a per-cpu
pool.  Also, we make sure the the nonblocking pool used by urandom is
initialized before we start feeding the normal input pool.  This
assures that /dev/urandom is returning unpredictable data as soon as
possible.

(Based on an original patch by Linus, but significantly modified by
tytso.)

Tested-by: Eric Wustrow 
Reported-by: Eric Wustrow 
Reported-by: Nadia Heninger 
Reported-by: Zakir Durumeric 
Reported-by: J. Alex Halderman .
Signed-off-by: Linus Torvalds 
Signed-off-by: "Theodore Ts'o" 
[PG: minor adjustment required since .34 doesn't have f9e4989eb8
 which renames "status" to "random" in kernel/irq/handle.c ]
Signed-off-by: Paul Gortmaker

genirq: Add IRQF_RESUME_EARLY and resume such IRQs earlier

2012-05-17T15:20:54+00:00

commit 9bab0b7fbaceec47d32db51cd9e59c82fb071f5a upstream

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 676dc3cf5bc3 "xen: Use IRQF_FORCE_RESUME".

Back ported to 2.6.32 (which lacks syscore support) by calling the relavant
resume function directly from sysdev_resume).

v2: Fixed non-x86 build errors.

Signed-off-by: Ian Campbell 
Cc: Rafael J. Wysocki 
Cc: Jeremy Fitzhardinge 
Cc: xen-devel 
Cc: Konrad Rzeszutek Wilk 
Link: http://lkml.kernel.org/r/1318713254.11016.52.camel@dagon.hellion.org.uk
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman 
[PG: this v2 backport taken from v2.6.32.49 stable, commit 5e87d8ee34e3]
Signed-off-by: Paul Gortmaker

genirq: Add IRQF_FORCE_RESUME

2012-05-17T15:20:54+00:00

commit dc5f219e88294b93009eef946251251ffffb6d60 upstream.

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: Ian Campbell 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Paul Gortmaker

genirq: Disable the SHIRQ_DEBUG call in request_threaded_irq for now

2011-06-26T16:46:47+00:00

commit 6d83f94db95cfe65d2a6359cccdf61cf087c2598 upstream.

With CONFIG_SHIRQ_DEBUG=y we call a newly installed interrupt handler
in request_threaded_irq().

The original implementation (commit a304e1b8) called the handler
_BEFORE_ it was installed, but that caused problems with handlers
calling disable_irq_nosync(). See commit 377bf1e4.

It's braindead in the first place to call disable_irq_nosync in shared
handlers, but ....

Moving this call after we installed the handler looks innocent, but it
is very subtle broken on SMP.

Interrupt handlers rely on the fact, that the irq core prevents
reentrancy.

Now this debug call violates that promise because we run the handler
w/o the IRQ_INPROGRESS protection - which we cannot apply here because
that would result in a possibly forever masked interrupt line.

A concurrent real hardware interrupt on a different CPU results in
handler reentrancy and can lead to complete wreckage, which was
unfortunately observed in reality and took a fricking long time to
debug.

Leave the code here for now. We want this debug feature, but that's
not easy to fix. We really should get rid of those
disable_irq_nosync() abusers and remove that function completely.

Signed-off-by: Thomas Gleixner 
Cc: Anton Vorontsov 
Cc: David Woodhouse 
Cc: Arjan van de Ven 
Signed-off-by: Paul Gortmaker

irq: Add new IRQ flag IRQF_NO_SUSPEND

2010-08-13T20:27:34+00:00

commit 685fd0b4ea3f0f1d5385610b0d5b57775a8d5842 upstream.

A small number of users of IRQF_TIMER are using it for the implied no
suspend behaviour on interrupts which are not timer interrupts.

Therefore add a new IRQF_NO_SUSPEND flag, rename IRQF_TIMER to
__IRQF_TIMER and redefine IRQF_TIMER in terms of these new flags.

Signed-off-by: Ian Campbell 
Cc: Jeremy Fitzhardinge 
Cc: Dmitry Torokhov 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Grant Likely 
Cc: xen-devel@lists.xensource.com
Cc: linux-input@vger.kernel.org
Cc: linuxppc-dev@ozlabs.org
Cc: devicetree-discuss@lists.ozlabs.org
LKML-Reference: <1280398595-29708-1-git-send-email-ian.campbell@citrix.com>
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

genirq: Deal with desc->set_type() changing desc->chip

2010-08-02T17:29:46+00:00

commit 4673247562e39a17e09440fa1400819522ccd446 upstream.

The set_type() function can change the chip implementation when the
trigger mode changes. That might result in using an non-initialized
irq chip when called from __setup_irq() or when called via
set_irq_type() on an already enabled irq.

The set_irq_type() function should not be called on an enabled irq,
but because we forgot to put a check into it, we have a bunch of users
which grew the habit of doing that and it never blew up as the
function is serialized via desc->lock against all users of desc->chip
and they never hit the non-initialized irq chip issue.

The easy fix for the __setup_irq() issue would be to move the
irq_chip_set_defaults(desc->chip) call after the trigger setting to
make sure that a chip change is covered.

But as we have already users, which do the type setting after
request_irq(), the safe fix for now is to call irq_chip_set_defaults()
from __irq_set_trigger() when desc->set_type() changed the irq chip.

It needs a deeper analysis whether we should refuse to change the chip
on an already enabled irq, but that'd be a large scale change to fix
all the existing users. So that's neither stable nor 2.6.35 material.

Reported-by: Esben Haabendal 
Signed-off-by: Thomas Gleixner 
Cc: Benjamin Herrenschmidt 
Cc: linuxppc-dev 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2010-04-06T20:03:22+00:00

* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  genirq: Force MSI irq handlers to run with interrupts disabled

genirq: Force MSI irq handlers to run with interrupts disabled

2010-03-31T13:48:38+00:00

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: Thomas Gleixner 
Cc: Andi Kleen 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Alan Cox 
Cc: David Miller 
Cc: Greg Kroah-Hartman 
Cc: Arnaldo Carvalho de Melo 
Cc: stable@kernel.org