linux.git/kernel/irq/internals.h, branch v3.19

genirq: Prevent proc race against freeing of irq descriptors

2014-12-13T12:33:07+00:00

Since the rework of the sparse interrupt code to actually free the
unused interrupt descriptors there exists a race between the /proc
interfaces to the irq subsystem and the code which frees the interrupt
descriptor.

CPU0				CPU1
				show_interrupts()
				  desc = irq_to_desc(X);
free_desc(desc)
  remove_from_radix_tree();
  kfree(desc);
				  raw_spinlock_irq(&desc->lock);

/proc/interrupts is the only interface which can actively corrupt
kernel memory via the lock access. /proc/stat can only read from freed
memory. Extremly hard to trigger, but possible.

The interfaces in /proc/irq/N/ are not affected by this because the
removal of the proc file is serialized in procfs against concurrent
readers/writers. The removal happens before the descriptor is freed.

For architectures which have CONFIG_SPARSE_IRQ=n this is a non issue
as the descriptor is never freed. It's merely cleared out with the irq
descriptor lock held. So any concurrent proc access will either see
the old correct value or the cleared out ones.

Protect the lookup and access to the irq descriptor in
show_interrupts() with the sparse_irq_lock.

Provide kstat_irqs_usr() which is protecting the lookup and access
with sparse_irq_lock and switch /proc/stat to use it.

Document the existing kstat_irqs interfaces so it's clear that the
caller needs to take care about protection. The users of these
interfaces are either not affected due to SPARSE_IRQ=n or already
protected against removal.

Fixes: 1f5a5b87f78f "genirq: Implement a sane sparse_irq allocator"
Signed-off-by: Thomas Gleixner 
Cc: stable@vger.kernel.org

genirq: Simplify wakeup mechanism

2014-09-01T11:48:59+00:00

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: Thomas Gleixner 
[ rjw: syscore.c and put irq_pm_check_wakeup() into pm.c ]
Signed-off-by: Rafael J. Wysocki

genirq: Add sanity checks for PM options on shared interrupt lines

2014-09-01T11:48:05+00:00

Account the IRQF_NO_SUSPEND and IRQF_RESUME_EARLY actions on shared
interrupt lines and yell loudly if there is a mismatch.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Rafael J. Wysocki

genirq: Move suspend/resume logic into irq/pm code

2014-09-01T11:47:57+00:00

No functional change. Preparatory patch for cleaning up the suspend
abort functionality. Update the comments while at it.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Rafael J. Wysocki

genirq: Improve documentation to match current implementation

2014-05-27T08:16:44+00:00

Signed-off-by: Jiang Liu 
Cc: Konrad Rzeszutek Wilk 
Cc: Tony Luck 
Cc: Joerg Roedel 
Cc: Paul Gortmaker 
Cc: Greg Kroah-Hartman 
Cc: Benjamin Herrenschmidt 
Cc: Grant Likely 
Cc: Rafael J. Wysocki 
Cc: Bjorn Helgaas 
Cc: Randy Dunlap 
Cc: Yinghai Lu 
Cc: Jiri Kosina 
Link: http://lkml.kernel.org/r/1401178092-1228-3-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner

genirq: Replace reserve_irqs in core code

2014-05-16T12:05:22+00:00

We want to get rid of the public interface.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Grant Likely 
Tested-by: Tony Luck 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20140507154340.061990194@linutronix.de
Signed-off-by: Thomas Gleixner

genirq: Add a new IRQCHIP_EOI_THREADED flag

2014-03-14T12:43:33+00:00

The flag is necessary for interrupt chips which require an ACK/EOI
after the handler has run. In case of threaded handlers this needs to
happen after the threaded handler has completed before the unmask of
the interrupt.

The flag is only unseful in combination with the handle_fasteoi_irq
flow control handler.

It can be combined with the flag IRQCHIP_EOI_IF_HANDLED, so the EOI is
not issued when the interrupt is disabled or in progress.

Tested-by: Hans de Goede 
Reviewed-by: Hans de Goede 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-sunxi@googlegroups.com
Cc: Maxime Ripard 
Link: http://lkml.kernel.org/r/1394733834-26839-2-git-send-email-hdegoede@redhat.com
Signed-off-by: Thomas Gleixner

genirq: Move kstat_incr_irqs_this_cpu() to core

2014-03-04T16:37:54+00:00

No more users outside the core code. Put it into the poison
cabinet. That also gets rid of the linux/irq.h include in
kernel_stat.h

Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20140223212739.124207133@linutronix.de
Signed-off-by: Thomas Gleixner

genirq: Provide irq_wake_thread()

2014-02-19T16:22:44+00:00

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: Thomas Gleixner 
Cc: Russell King 
Cc: Chris Ball 
Acked-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20140215003823.772565780@linutronix.de

genirq: Introduce irq_do_set_affinity() to reduce duplicated code

2012-05-24T20:36:40+00:00

All invocations of chip->irq_set_affinity() are doing the same return
value checks. Let them all use a common function.

[ tglx: removed the silly likely while at it ]

Signed-off-by: Jiang Liu 
Cc: Jiang Liu 
Cc: Keping Chen 
Link: http://lkml.kernel.org/r/1333120296-13563-3-git-send-email-jiang.liu@huawei.com
Signed-off-by: Thomas Gleixner