<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/kernel/irq, branch v5.19.2</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>irqdomain: Report irq number for NOMAP domains</title>
<updated>2022-08-17T13:14:19+00:00</updated>
<author>
<name>Xu Qiang</name>
<email>xuqiang36@huawei.com</email>
</author>
<published>2022-07-19T06:36:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9987e2d15f51c67534689ce22c01343f50634419'/>
<id>9987e2d15f51c67534689ce22c01343f50634419</id>
<content type='text'>
[ Upstream commit 6f194c99f466147148cc08452718b46664112548 ]

When using a NOMAP domain, __irq_resolve_mapping() doesn't store
the Linux IRQ number at the address optionally provided by the caller.
While this isn't a huge deal (the returned value is guaranteed
to the hwirq that was passed as a parameter), let's honour the letter
of the API by writing the expected value.

Fixes: d22558dd0a6c (“irqdomain: Introduce irq_resolve_mapping()”)
Signed-off-by: Xu Qiang &lt;xuqiang36@huawei.com&gt;
[maz: commit message]
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/20220719063641.56541-2-xuqiang36@huawei.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 6f194c99f466147148cc08452718b46664112548 ]

When using a NOMAP domain, __irq_resolve_mapping() doesn't store
the Linux IRQ number at the address optionally provided by the caller.
While this isn't a huge deal (the returned value is guaranteed
to the hwirq that was passed as a parameter), let's honour the letter
of the API by writing the expected value.

Fixes: d22558dd0a6c (“irqdomain: Introduce irq_resolve_mapping()”)
Signed-off-by: Xu Qiang &lt;xuqiang36@huawei.com&gt;
[maz: commit message]
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/20220719063641.56541-2-xuqiang36@huawei.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>genirq: GENERIC_IRQ_IPI depends on SMP</title>
<updated>2022-08-17T13:14:01+00:00</updated>
<author>
<name>Samuel Holland</name>
<email>samuel@sholland.org</email>
</author>
<published>2022-07-01T20:00:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=4d4ccca64e84c6dc724232d2089f5bfcd704fa48'/>
<id>4d4ccca64e84c6dc724232d2089f5bfcd704fa48</id>
<content type='text'>
[ Upstream commit 0f5209fee90b4544c58b4278d944425292789967 ]

The generic IPI code depends on the IRQ affinity mask being allocated
and initialized. This will not be the case if SMP is disabled. Fix up
the remaining driver that selected GENERIC_IRQ_IPI in a non-SMP config.

Reported-by: kernel test robot &lt;lkp@intel.com&gt;
Signed-off-by: Samuel Holland &lt;samuel@sholland.org&gt;
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/20220701200056.46555-3-samuel@sholland.org
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 0f5209fee90b4544c58b4278d944425292789967 ]

The generic IPI code depends on the IRQ affinity mask being allocated
and initialized. This will not be the case if SMP is disabled. Fix up
the remaining driver that selected GENERIC_IRQ_IPI in a non-SMP config.

Reported-by: kernel test robot &lt;lkp@intel.com&gt;
Signed-off-by: Samuel Holland &lt;samuel@sholland.org&gt;
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/20220701200056.46555-3-samuel@sholland.org
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>genirq: Don't return error on missing optional irq_request_resources()</title>
<updated>2022-08-17T13:14:01+00:00</updated>
<author>
<name>Antonio Borneo</name>
<email>antonio.borneo@foss.st.com</email>
</author>
<published>2022-05-12T16:05:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=8fa8237d2d2b7e512c4eea084518346b8d9ac1fa'/>
<id>8fa8237d2d2b7e512c4eea084518346b8d9ac1fa</id>
<content type='text'>
[ Upstream commit 95001b756467ecc9f5973eb5e74e97699d9bbdf1 ]

Function irq_chip::irq_request_resources() is reported as optional
in the declaration of struct irq_chip.
If the parent irq_chip does not implement it, we should ignore it
and return.

Don't return error if the functions is missing.

Signed-off-by: Antonio Borneo &lt;antonio.borneo@foss.st.com&gt;
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/20220512160544.13561-1-antonio.borneo@foss.st.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 95001b756467ecc9f5973eb5e74e97699d9bbdf1 ]

Function irq_chip::irq_request_resources() is reported as optional
in the declaration of struct irq_chip.
If the parent irq_chip does not implement it, we should ignore it
and return.

Don't return error if the functions is missing.

Signed-off-by: Antonio Borneo &lt;antonio.borneo@foss.st.com&gt;
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/20220512160544.13561-1-antonio.borneo@foss.st.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>genirq: PM: Use runtime PM for chained interrupts</title>
<updated>2022-06-09T14:58:13+00:00</updated>
<author>
<name>Marc Zyngier</name>
<email>maz@kernel.org</email>
</author>
<published>2022-06-08T13:45:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=668a9fe5c6a1bcac6b65d5e9b91a9eca86f782a3'/>
<id>668a9fe5c6a1bcac6b65d5e9b91a9eca86f782a3</id>
<content type='text'>
When requesting an interrupt, we correctly call into the runtime
PM framework to guarantee that the underlying interrupt controller
is up and running.

However, we fail to do so for chained interrupt controllers, as
the mux interrupt is not requested along the same path.

Augment __irq_do_set_handler() to call into the runtime PM code
in this case, making sure the PM flow is the same for all interrupts.

Reported-by: Lucas Stach &lt;l.stach@pengutronix.de&gt;
Tested-by: Liu Ying &lt;victor.liu@nxp.com&gt;
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/26973cddee5f527ea17184c0f3fccb70bc8969a0.camel@pengutronix.de
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When requesting an interrupt, we correctly call into the runtime
PM framework to guarantee that the underlying interrupt controller
is up and running.

However, we fail to do so for chained interrupt controllers, as
the mux interrupt is not requested along the same path.

Augment __irq_do_set_handler() to call into the runtime PM code
in this case, making sure the PM flow is the same for all interrupts.

Reported-by: Lucas Stach &lt;l.stach@pengutronix.de&gt;
Tested-by: Liu Ying &lt;victor.liu@nxp.com&gt;
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/26973cddee5f527ea17184c0f3fccb70bc8969a0.camel@pengutronix.de
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'irq-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2022-05-23T23:58:49+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-05-23T23:58:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=fcfde8a7cf6d5e347ce61d8e5c0aee52926ef8e9'/>
<id>fcfde8a7cf6d5e347ce61d8e5c0aee52926ef8e9</id>
<content type='text'>
Pull interrupt handling updates from Thomas Gleixner:
 "Core code:

   - Make the managed interrupts more robust by shutting them down in
     the core code when the assigned affinity mask does not contain
     online CPUs.

   - Make the irq simulator chip work on RT

   - A small set of cpumask and power manageent cleanups

  Drivers:

   - A set of changes which mark GPIO interrupt chips immutable to
     prevent the GPIO subsystem from modifying it under the hood. This
     provides the necessary infrastructure and converts a set of GPIO
     and pinctrl drivers over.

   - A set of changes to make the pseudo-NMI handling for GICv3 more
     robust: a missing barrier and consistent handling of the priority
     mask.

   - Another set of GICv3 improvements and fixes, but nothing
     outstanding

   - The usual set of improvements and cleanups all over the place

   - No new irqchip drivers and not even a new device tree binding!
     100+ interrupt chips are truly enough"

* tag 'irq-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
  irqchip: Add Kconfig symbols for sunxi drivers
  irqchip/gic-v3: Fix priority mask handling
  irqchip/gic-v3: Refactor ISB + EOIR at ack time
  irqchip/gic-v3: Ensure pseudo-NMIs have an ISB between ack and handling
  genirq/irq_sim: Make the irq_work always run in hard irq context
  irqchip/armada-370-xp: Do not touch Performance Counter Overflow on A375, A38x, A39x
  irqchip/gic: Improved warning about incorrect type
  irqchip/csky: Return true/false (not 1/0) from bool functions
  irqchip/imx-irqsteer: Add runtime PM support
  irqchip/imx-irqsteer: Constify irq_chip struct
  irqchip/armada-370-xp: Enable MSI affinity configuration
  irqchip/aspeed-scu-ic: Fix irq_of_parse_and_map() return value
  irqchip/aspeed-i2c-ic: Fix irq_of_parse_and_map() return value
  irqchip/sun6i-r: Use NULL for chip_data
  irqchip/xtensa-mx: Fix initial IRQ affinity in non-SMP setup
  irqchip/exiu: Fix acknowledgment of edge triggered interrupts
  irqchip/gic-v3: Claim iomem resources
  dt-bindings: interrupt-controller: arm,gic-v3: Make the v2 compat requirements explicit
  irqchip/gic-v3: Relax polling of GIC{R,D}_CTLR.RWP
  irqchip/gic-v3: Detect LPI invalidation MMIO registers
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull interrupt handling updates from Thomas Gleixner:
 "Core code:

   - Make the managed interrupts more robust by shutting them down in
     the core code when the assigned affinity mask does not contain
     online CPUs.

   - Make the irq simulator chip work on RT

   - A small set of cpumask and power manageent cleanups

  Drivers:

   - A set of changes which mark GPIO interrupt chips immutable to
     prevent the GPIO subsystem from modifying it under the hood. This
     provides the necessary infrastructure and converts a set of GPIO
     and pinctrl drivers over.

   - A set of changes to make the pseudo-NMI handling for GICv3 more
     robust: a missing barrier and consistent handling of the priority
     mask.

   - Another set of GICv3 improvements and fixes, but nothing
     outstanding

   - The usual set of improvements and cleanups all over the place

   - No new irqchip drivers and not even a new device tree binding!
     100+ interrupt chips are truly enough"

* tag 'irq-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
  irqchip: Add Kconfig symbols for sunxi drivers
  irqchip/gic-v3: Fix priority mask handling
  irqchip/gic-v3: Refactor ISB + EOIR at ack time
  irqchip/gic-v3: Ensure pseudo-NMIs have an ISB between ack and handling
  genirq/irq_sim: Make the irq_work always run in hard irq context
  irqchip/armada-370-xp: Do not touch Performance Counter Overflow on A375, A38x, A39x
  irqchip/gic: Improved warning about incorrect type
  irqchip/csky: Return true/false (not 1/0) from bool functions
  irqchip/imx-irqsteer: Add runtime PM support
  irqchip/imx-irqsteer: Constify irq_chip struct
  irqchip/armada-370-xp: Enable MSI affinity configuration
  irqchip/aspeed-scu-ic: Fix irq_of_parse_and_map() return value
  irqchip/aspeed-i2c-ic: Fix irq_of_parse_and_map() return value
  irqchip/sun6i-r: Use NULL for chip_data
  irqchip/xtensa-mx: Fix initial IRQ affinity in non-SMP setup
  irqchip/exiu: Fix acknowledgment of edge triggered interrupts
  irqchip/gic-v3: Claim iomem resources
  dt-bindings: interrupt-controller: arm,gic-v3: Make the v2 compat requirements explicit
  irqchip/gic-v3: Relax polling of GIC{R,D}_CTLR.RWP
  irqchip/gic-v3: Detect LPI invalidation MMIO registers
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'irqchip-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/core</title>
<updated>2022-05-20T16:48:54+00:00</updated>
<author>
<name>Thomas Gleixner</name>
<email>tglx@linutronix.de</email>
</author>
<published>2022-05-20T16:48:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=cdb4913293897dde0df522ed5789ba016f3b9157'/>
<id>cdb4913293897dde0df522ed5789ba016f3b9157</id>
<content type='text'>
Pull irqchip updates from Marc Zyngier:

 - Add new infrastructure to stop gpiolib from rewriting irq_chip
   structures behind our back. Convert a few of them, but this will
   obviously be a long effort.

 - A bunch of GICv3 improvements, such as using MMIO-based invalidations
   when possible, and reducing the amount of polling we perform when
   reconfiguring interrupts.

 - Another set of GICv3 improvements for the Pseudo-NMI functionality,
   with a nice cleanup making it easy to reason about the various
   states we can be in when an NMI fires.

 - The usual bunch of misc fixes and minor improvements.

Link: https://lore.kernel.org/all/20220519165308.998315-1-maz@kernel.org
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull irqchip updates from Marc Zyngier:

 - Add new infrastructure to stop gpiolib from rewriting irq_chip
   structures behind our back. Convert a few of them, but this will
   obviously be a long effort.

 - A bunch of GICv3 improvements, such as using MMIO-based invalidations
   when possible, and reducing the amount of polling we perform when
   reconfiguring interrupts.

 - Another set of GICv3 improvements for the Pseudo-NMI functionality,
   with a nice cleanup making it easy to reason about the various
   states we can be in when an NMI fires.

 - The usual bunch of misc fixes and minor improvements.

Link: https://lore.kernel.org/all/20220519165308.998315-1-maz@kernel.org
</pre>
</div>
</content>
</entry>
<entry>
<title>genirq/irq_sim: Make the irq_work always run in hard irq context</title>
<updated>2022-05-14T15:48:27+00:00</updated>
<author>
<name>Sebastian Andrzej Siewior</name>
<email>bigeasy@linutronix.de</email>
</author>
<published>2022-05-11T11:07:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=21673fcb2532dcd189905ff5a5389eb7dcd0e57a'/>
<id>21673fcb2532dcd189905ff5a5389eb7dcd0e57a</id>
<content type='text'>
The IRQ simulator uses irq_work to trigger an interrupt. Without the
IRQ_WORK_HARD_IRQ flag the irq_work will be performed in thread context
on PREEMPT_RT. This causes locking errors later in handle_simple_irq()
which expects to be invoked with disabled interrupts.

Triggering individual interrupts in hardirq context should not lead to
unexpected high latencies since this is also what the hardware
controller does. Also it is used as a simulator so...

Use IRQ_WORK_INIT_HARD() to carry out the irq_work in hardirq context on
PREEMPT_RT.

Signed-off-by: Sebastian Andrzej Siewior &lt;bigeasy@linutronix.de&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: https://lore.kernel.org/r/YnuZBoEVMGwKkLm+@linutronix.de
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The IRQ simulator uses irq_work to trigger an interrupt. Without the
IRQ_WORK_HARD_IRQ flag the irq_work will be performed in thread context
on PREEMPT_RT. This causes locking errors later in handle_simple_irq()
which expects to be invoked with disabled interrupts.

Triggering individual interrupts in hardirq context should not lead to
unexpected high latencies since this is also what the hardware
controller does. Also it is used as a simulator so...

Use IRQ_WORK_INIT_HARD() to carry out the irq_work in hardirq context on
PREEMPT_RT.

Signed-off-by: Sebastian Andrzej Siewior &lt;bigeasy@linutronix.de&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: https://lore.kernel.org/r/YnuZBoEVMGwKkLm+@linutronix.de
</pre>
</div>
</content>
</entry>
<entry>
<title>genirq: Remove WARN_ON_ONCE() in generic_handle_domain_irq()</title>
<updated>2022-05-11T00:22:52+00:00</updated>
<author>
<name>Lukas Wunner</name>
<email>lukas@wunner.de</email>
</author>
<published>2022-05-10T07:56:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=792ea6a074ae7ea5ab6f1b8b31f76bb0297de66c'/>
<id>792ea6a074ae7ea5ab6f1b8b31f76bb0297de66c</id>
<content type='text'>
Since commit 0953fb263714 ("irq: remove handle_domain_{irq,nmi}()"),
generic_handle_domain_irq() warns if called outside hardirq context, even
though the function calls down to handle_irq_desc(), which warns about the
same, but conditionally on handle_enforce_irqctx().

The newly added warning is a false positive if the interrupt originates
from any other irqchip than x86 APIC or ARM GIC/GICv3.  Those are the only
ones for which handle_enforce_irqctx() returns true.  Per commit
c16816acd086 ("genirq: Add protection against unsafe usage of
generic_handle_irq()"):

 "In general calling generic_handle_irq() with interrupts disabled from non
  interrupt context is harmless. For some interrupt controllers like the
  x86 trainwrecks this is outright dangerous as it might corrupt state if
  an interrupt affinity change is pending."

Examples for interrupt chips where the warning is a false positive are
USB-attached GPIO controllers such as drivers/gpio/gpio-dln2.c:

  USB gadgets are incapable of directly signaling an interrupt because they
  cannot initiate a bus transaction by themselves.  All communication on
  the bus is initiated by the host controller, which polls a gadget's
  Interrupt Endpoint in regular intervals.  If an interrupt is pending,
  that information is passed up the stack in softirq context, from which a
  hardirq is synthesized via generic_handle_domain_irq().

Remove the warning to eliminate such false positives.

Fixes: 0953fb263714 ("irq: remove handle_domain_{irq,nmi}()")
Signed-off-by: Lukas Wunner &lt;lukas@wunner.de&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Marc Zyngier &lt;maz@kernel.org&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Jakub Kicinski &lt;kuba@kernel.org&gt;
CC: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Cc: Bartosz Golaszewski &lt;brgl@bgdev.pl&gt;
Cc: Octavian Purdila &lt;octavian.purdila@nxp.com&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220505113207.487861b2@kernel.org
Link: https://lore.kernel.org/r/20220506203242.GA1855@wunner.de
Link: https://lore.kernel.org/r/c3caf60bfa78e5fdbdf483096b7174da65d1813a.1652168866.git.lukas@wunner.de
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Since commit 0953fb263714 ("irq: remove handle_domain_{irq,nmi}()"),
generic_handle_domain_irq() warns if called outside hardirq context, even
though the function calls down to handle_irq_desc(), which warns about the
same, but conditionally on handle_enforce_irqctx().

The newly added warning is a false positive if the interrupt originates
from any other irqchip than x86 APIC or ARM GIC/GICv3.  Those are the only
ones for which handle_enforce_irqctx() returns true.  Per commit
c16816acd086 ("genirq: Add protection against unsafe usage of
generic_handle_irq()"):

 "In general calling generic_handle_irq() with interrupts disabled from non
  interrupt context is harmless. For some interrupt controllers like the
  x86 trainwrecks this is outright dangerous as it might corrupt state if
  an interrupt affinity change is pending."

Examples for interrupt chips where the warning is a false positive are
USB-attached GPIO controllers such as drivers/gpio/gpio-dln2.c:

  USB gadgets are incapable of directly signaling an interrupt because they
  cannot initiate a bus transaction by themselves.  All communication on
  the bus is initiated by the host controller, which polls a gadget's
  Interrupt Endpoint in regular intervals.  If an interrupt is pending,
  that information is passed up the stack in softirq context, from which a
  hardirq is synthesized via generic_handle_domain_irq().

Remove the warning to eliminate such false positives.

Fixes: 0953fb263714 ("irq: remove handle_domain_{irq,nmi}()")
Signed-off-by: Lukas Wunner &lt;lukas@wunner.de&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Marc Zyngier &lt;maz@kernel.org&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Jakub Kicinski &lt;kuba@kernel.org&gt;
CC: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Cc: Bartosz Golaszewski &lt;brgl@bgdev.pl&gt;
Cc: Octavian Purdila &lt;octavian.purdila@nxp.com&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220505113207.487861b2@kernel.org
Link: https://lore.kernel.org/r/20220506203242.GA1855@wunner.de
Link: https://lore.kernel.org/r/c3caf60bfa78e5fdbdf483096b7174da65d1813a.1652168866.git.lukas@wunner.de
</pre>
</div>
</content>
</entry>
<entry>
<title>genirq: Synchronize interrupt thread startup</title>
<updated>2022-05-05T09:54:05+00:00</updated>
<author>
<name>Thomas Pfaff</name>
<email>tpfaff@pcs.com</email>
</author>
<published>2022-05-02T11:28:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=8707898e22fd665bc1d7b18b809be4b56ce25bdd'/>
<id>8707898e22fd665bc1d7b18b809be4b56ce25bdd</id>
<content type='text'>
A kernel hang can be observed when running setserial in a loop on a kernel
with force threaded interrupts. The sequence of events is:

   setserial
     open("/dev/ttyXXX")
       request_irq()
     do_stuff()
      -&gt; serial interrupt
         -&gt; wake(irq_thread)
	      desc-&gt;threads_active++;
     close()
       free_irq()
         kthread_stop(irq_thread)
     synchronize_irq() &lt;- hangs because desc-&gt;threads_active != 0

The thread is created in request_irq() and woken up, but does not get on a
CPU to reach the actual thread function, which would handle the pending
wake-up. kthread_stop() sets the should stop condition which makes the
thread immediately exit, which in turn leaves the stale threads_active
count around.

This problem was introduced with commit 519cc8652b3a, which addressed a
interrupt sharing issue in the PCIe code.

Before that commit free_irq() invoked synchronize_irq(), which waits for
the hard interrupt handler and also for associated threads to complete.

To address the PCIe issue synchronize_irq() was replaced with
__synchronize_hardirq(), which only waits for the hard interrupt handler to
complete, but not for threaded handlers.

This was done under the assumption, that the interrupt thread already
reached the thread function and waits for a wake-up, which is guaranteed to
be handled before acting on the stop condition. The problematic case, that
the thread would not reach the thread function, was obviously overlooked.

Make sure that the interrupt thread is really started and reaches
thread_fn() before returning from __setup_irq().

This utilizes the existing wait queue in the interrupt descriptor. The
wait queue is unused for non-shared interrupts. For shared interrupts the
usage might cause a spurious wake-up of a waiter in synchronize_irq() or the
completion of a threaded handler might cause a spurious wake-up of the
waiter for the ready flag. Both are harmless and have no functional impact.

[ tglx: Amended changelog ]

Fixes: 519cc8652b3a ("genirq: Synchronize only with single thread on free_irq()")
Signed-off-by: Thomas Pfaff &lt;tpfaff@pcs.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Reviewed-by: Marc Zyngier &lt;maz@kernel.org&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/552fe7b4-9224-b183-bb87-a8f36d335690@pcs.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
A kernel hang can be observed when running setserial in a loop on a kernel
with force threaded interrupts. The sequence of events is:

   setserial
     open("/dev/ttyXXX")
       request_irq()
     do_stuff()
      -&gt; serial interrupt
         -&gt; wake(irq_thread)
	      desc-&gt;threads_active++;
     close()
       free_irq()
         kthread_stop(irq_thread)
     synchronize_irq() &lt;- hangs because desc-&gt;threads_active != 0

The thread is created in request_irq() and woken up, but does not get on a
CPU to reach the actual thread function, which would handle the pending
wake-up. kthread_stop() sets the should stop condition which makes the
thread immediately exit, which in turn leaves the stale threads_active
count around.

This problem was introduced with commit 519cc8652b3a, which addressed a
interrupt sharing issue in the PCIe code.

Before that commit free_irq() invoked synchronize_irq(), which waits for
the hard interrupt handler and also for associated threads to complete.

To address the PCIe issue synchronize_irq() was replaced with
__synchronize_hardirq(), which only waits for the hard interrupt handler to
complete, but not for threaded handlers.

This was done under the assumption, that the interrupt thread already
reached the thread function and waits for a wake-up, which is guaranteed to
be handled before acting on the stop condition. The problematic case, that
the thread would not reach the thread function, was obviously overlooked.

Make sure that the interrupt thread is really started and reaches
thread_fn() before returning from __setup_irq().

This utilizes the existing wait queue in the interrupt descriptor. The
wait queue is unused for non-shared interrupts. For shared interrupts the
usage might cause a spurious wake-up of a waiter in synchronize_irq() or the
completion of a threaded handler might cause a spurious wake-up of the
waiter for the ready flag. Both are harmless and have no functional impact.

[ tglx: Amended changelog ]

Fixes: 519cc8652b3a ("genirq: Synchronize only with single thread on free_irq()")
Signed-off-by: Thomas Pfaff &lt;tpfaff@pcs.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Reviewed-by: Marc Zyngier &lt;maz@kernel.org&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/552fe7b4-9224-b183-bb87-a8f36d335690@pcs.com
</pre>
</div>
</content>
</entry>
<entry>
<title>genirq: Use pm_runtime_resume_and_get() instead of pm_runtime_get_sync()</title>
<updated>2022-05-02T12:08:08+00:00</updated>
<author>
<name>Minghao Chi</name>
<email>chi.minghao@zte.com.cn</email>
</author>
<published>2022-04-18T11:07:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ce4818957fdc5bca57fc2c92b0dfe109d26bcc47'/>
<id>ce4818957fdc5bca57fc2c92b0dfe109d26bcc47</id>
<content type='text'>
pm_runtime_resume_and_get() achieves the same and simplifies the code.

[ tglx: Simplify it further by presetting retval ]

Reported-by: Zeal Robot &lt;zealci@zte.com.cn&gt;
Signed-off-by: Minghao Chi &lt;chi.minghao@zte.com.cn&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: https://lore.kernel.org/r/20220418110716.2559453-1-chi.minghao@zte.com.cn
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
pm_runtime_resume_and_get() achieves the same and simplifies the code.

[ tglx: Simplify it further by presetting retval ]

Reported-by: Zeal Robot &lt;zealci@zte.com.cn&gt;
Signed-off-by: Minghao Chi &lt;chi.minghao@zte.com.cn&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: https://lore.kernel.org/r/20220418110716.2559453-1-chi.minghao@zte.com.cn
</pre>
</div>
</content>
</entry>
</feed>
