linux.git/kernel/irq, branch v6.18.21

genirq/cpuhotplug: Notify about affinity changes breaking the affinity mask

2026-03-04T12:19:40+00:00

[ Upstream commit dd9f6d30c64001ca4dde973ac04d8d155e856743 ]

During CPU offlining the interrupts affined to that CPU are moved to other
online CPUs, which might break the original affinity mask if the outgoing
CPU was the last online CPU in that mask. This change is not propagated to
irq_desc::affinity_notify(), which leaves users of the affinity notifier
mechanism with stale information.

Avoid this by scheduling affinity change notification work for interrupts
that were affined to the CPU being offlined, if the new target CPU is not
part of the original affinity mask.

Since irq_set_affinity_locked() uses the same logic to schedule affinity
change notification work, split out this logic into a dedicated function
and use that at both places.

[ tglx: Removed the EXPORT(), removed the !SMP stub, moved the prototype,
  	added a lockdep assert instead of a comment, fixed up coding style
  	and name space. Polished and clarified the change log ]

Signed-off-by: Imran Khan 
Signed-off-by: Thomas Gleixner 
Link: https://patch.msgid.link/20260113143727.1041265-1-imran.f.khan@oracle.com
Signed-off-by: Sasha Levin

genirq/manage: Add buslock back in to enable_irq()

2025-10-24T09:38:39+00:00

The locking was changed from a buslock to a plain lock, but the patch
description states there was no functional change. Assuming this was
accidental so reverting to using the buslock.

Fixes: bddd10c55407 ("genirq/manage: Rework enable_irq()")
Signed-off-by: Charles Keepax 
Signed-off-by: Thomas Gleixner 
Link: https://patch.msgid.link/20251023154901.1333755-4-ckeepax@opensource.cirrus.com

genirq/manage: Add buslock back in to __disable_irq_nosync()

2025-10-24T09:38:39+00:00

The locking was changed from a buslock to a plain lock, but the patch
description states there was no functional change. Assuming this was
accidental so reverting to using the buslock.

Fixes: 1b7444446724 ("genirq/manage: Rework __disable_irq_nosync()")
Signed-off-by: Charles Keepax 
Signed-off-by: Thomas Gleixner 
Link: https://patch.msgid.link/20251023154901.1333755-3-ckeepax@opensource.cirrus.com

genirq/chip: Add buslock back in to irq_set_handler()

2025-10-24T09:38:39+00:00

The locking was changed from a buslock to a plain lock, but the patch
description states there was no functional change. Assuming this was
accidental so reverting to using the buslock.

Fixes: 5cd05f3e2315 ("genirq/chip: Rework irq_set_handler() variants")
Signed-off-by: Charles Keepax 
Signed-off-by: Thomas Gleixner 
Link: https://patch.msgid.link/20251023154901.1333755-2-ckeepax@opensource.cirrus.com

Merge tag 'irq-core-2025-09-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2025-09-30T22:55:25+00:00

Pull irq core updates from Thomas Gleixner:
 "A set of updates for the interrupt core subsystem:

   - Introduce irq_chip_[startup|shutdown]_parent() to prepare for
     addressing a few short comings in the PCI/MSI interrupt subsystem.

     It allows to utilize the interrupt chip startup/shutdown callbacks
     for initializing the interrupt chip hierarchy properly on certain
     RISCV implementations and provides a mechanism to reduce the
     overhead of masking and unmasking PCI/MSI interrupts during
     operation when the underlying MSI provider can mask the interrupt.

     The actual usage comes with the interrupt driver pull request.

   - Add generic error handling for devm_request_*_irq()

     This allows to remove the zoo of random error printk's all over the
     usage sites.

   - Add a mechanism to warn about long-running interrupt handlers

     Long running interrupt handlers can introduce latencies and
     tracking them down is a tedious task. The tracking has to be
     enabled with a threshold on the kernel command line and utilizes a
     static branch to remove the overhead when disabled.

   - Update and extend the selftests which validate the CPU hotplug
     interrupt migration logic

   - Allow dropping the per CPU softirq lock on PREEMPT_RT kernels,
     which causes contention and latencies all over the place.

     The serialization requirements have been pushed down into the
     actual affected usage sites already.

   - The usual small cleanups and improvements"

* tag 'irq-core-2025-09-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT
  softirq: Provide a handshake for canceling tasklets via polling
  genirq/test: Ensure CPU 1 is online for hotplug test
  genirq/test: Drop CONFIG_GENERIC_IRQ_MIGRATION assumptions
  genirq/test: Depend on SPARSE_IRQ
  genirq/test: Fail early if interrupt request fails
  genirq/test: Factor out fake-virq setup
  genirq/test: Select IRQ_DOMAIN
  genirq/test: Fix depth tests on architectures with NOREQUEST by default.
  genirq: Add support for warning on long-running interrupt handlers
  genirq/devres: Add error handling in devm_request_*_irq()
  genirq: Add irq_chip_(startup/shutdown)_parent()
  genirq: Remove GENERIC_IRQ_LEGACY

genirq/msi: Remove msi_post_free()

2025-09-23T08:59:51+00:00

The only user of msi_post_free() - powerpc/pseries - has been changed to
use msi_teardown().

Remove this unused callback.

Signed-off-by: Nam Cao 
Reviewed-by: Thomas Gleixner 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20250916061007.964005-1-namcao@linutronix.de

genirq/test: Ensure CPU 1 is online for hotplug test

2025-09-03T15:04:52+00:00

It's possible to run these tests on platforms that think they have a
hotpluggable CPU1, but for whatever reason, CPU1 is not online and can't be
brought online:

    # irq_cpuhotplug_test: EXPECTATION FAILED at kernel/irq/irq_test.c:210
    Expected remove_cpu(1) == 0, but
        remove_cpu(1) == 1 (0x1)
CPU1: failed to boot: -38
    # irq_cpuhotplug_test: EXPECTATION FAILED at kernel/irq/irq_test.c:214
    Expected add_cpu(1) == 0, but
        add_cpu(1) == -38 (0xffffffffffffffda)

Check that CPU1 is actually online before trying to run the test.

Fixes: 66067c3c8a1e ("genirq: Add kunit tests for depth counts")
Reported-by: Guenter Roeck 
Signed-off-by: Brian Norris 
Signed-off-by: Thomas Gleixner 
Tested-by: Guenter Roeck 
Reviewed-by: David Gow 
Link: https://lore.kernel.org/all/20250822190140.2154646-7-briannorris@chromium.org

genirq/test: Drop CONFIG_GENERIC_IRQ_MIGRATION assumptions

2025-09-03T15:04:52+00:00

Not all platforms use the generic IRQ migration code, even if they select
GENERIC_IRQ_MIGRATION. (See, for example, powerpc / pseries_cpu_disable().)

If such platforms don't perform managed shutdown the same way, the interrupt
may not actually shut down, and these tests fail:

[    4.357022][  T101]     # irq_cpuhotplug_test: EXPECTATION FAILED at kernel/irq/irq_test.c:211
[    4.357022][  T101]     Expected irqd_is_activated(data) to be false, but is true
[    4.358128][  T101]     # irq_cpuhotplug_test: EXPECTATION FAILED at kernel/irq/irq_test.c:212
[    4.358128][  T101]     Expected irqd_is_started(data) to be false, but is true
[    4.375558][  T101]     # irq_cpuhotplug_test: EXPECTATION FAILED at kernel/irq/irq_test.c:216
[    4.375558][  T101]     Expected irqd_is_activated(data) to be false, but is true
[    4.376088][  T101]     # irq_cpuhotplug_test: EXPECTATION FAILED at kernel/irq/irq_test.c:217
[    4.376088][  T101]     Expected irqd_is_started(data) to be false, but is true
[    4.377851][    T1]     # irq_cpuhotplug_test: pass:0 fail:1 skip:0 total:1
[    4.377901][    T1]     not ok 4 irq_cpuhotplug_test
[    4.378073][    T1] # irq_test_cases: pass:3 fail:1 skip:0 total:4

Rather than test that PowerPC performs migration the same way as the
unterrupt core, just drop the state checks. The point of the test was to
ensure that the code kept |depth| balanced, which still can be tested for.

Fixes: 66067c3c8a1e ("genirq: Add kunit tests for depth counts")
Reported-by: Guenter Roeck 
Signed-off-by: Brian Norris 
Signed-off-by: Thomas Gleixner 
Tested-by: Guenter Roeck 
Reviewed-by: David Gow 
Link: https://lore.kernel.org/all/20250822190140.2154646-6-briannorris@chromium.org

genirq/test: Depend on SPARSE_IRQ

2025-09-03T15:04:52+00:00

Some architectures have a static interrupt layout, with a limited number of
interrupts. Without SPARSE_IRQ, the test may not be able to allocate any
fake interrupts, and the test will fail. (This occurs on ARCH=m68k, for
example.)

Additionally, managed-affinity is only supported with CONFIG_SPARSE_IRQ=y,
so irq_shutdown_depth_test() and irq_cpuhotplug_test() would fail without
it.

Add a 'SPARSE_IRQ' dependency to avoid these problems.

Many architectures 'select SPARSE_IRQ', so this is easy to miss.

Notably, this also excludes ARCH=um from running any of these tests, even
though some of them might work.

Fixes: 66067c3c8a1e ("genirq: Add kunit tests for depth counts")
Reported-by: Guenter Roeck 
Signed-off-by: Brian Norris 
Signed-off-by: Thomas Gleixner 
Tested-by: Guenter Roeck 
Reviewed-by: David Gow 
Link: https://lore.kernel.org/all/20250822190140.2154646-5-briannorris@chromium.org

genirq/test: Fail early if interrupt request fails

2025-09-03T15:04:52+00:00

Requesting an interrupt is part of the basic test setup. If it fails, most
of the subsequent tests are likely to fail, and the output gets noisy.

Use "assert" to fail early.

Signed-off-by: Brian Norris 
Signed-off-by: Thomas Gleixner 
Tested-by: Guenter Roeck 
Reviewed-by: David Gow 
Link: https://lore.kernel.org/all/20250822190140.2154646-4-briannorris@chromium.org