Commit 3b2074c7 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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

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
parents 1d17e808 3253cb49

Documentation/admin-guide/kernel-parameters.txt

+5 −0
Original line number Diff line number Diff line
@@ -2606,6 +2606,11 @@ 
			for it. Intended to get systems with badly broken

			firmware running.



	irqhandler.duration_warn_us= [KNL]

			Warn if an IRQ handler exceeds the specified duration

			threshold in microseconds. Useful for identifying

			long-running IRQs in the system.



	irqpoll		[HW]

			When an interrupt is not handled search all handlers

			for it. Also check all handlers each timer

include/linux/irq.h

+2 −4
Original line number Diff line number Diff line
@@ -669,6 +669,8 @@ extern int irq_chip_set_parent_state(struct irq_data *data, 
extern int irq_chip_get_parent_state(struct irq_data *data,

				     enum irqchip_irq_state which,

				     bool *state);

extern void irq_chip_shutdown_parent(struct irq_data *data);

extern unsigned int irq_chip_startup_parent(struct irq_data *data);

extern void irq_chip_enable_parent(struct irq_data *data);

extern void irq_chip_disable_parent(struct irq_data *data);

extern void irq_chip_ack_parent(struct irq_data *data);
@@ -976,10 +978,6 @@ static inline void irq_free_desc(unsigned int irq) 
	irq_free_descs(irq, 1);

}



#ifdef CONFIG_GENERIC_IRQ_LEGACY

void irq_init_desc(unsigned int irq);

#endif



/**

 * struct irq_chip_regs - register offsets for struct irq_gci

 * @enable:	Enable register offset to reg_base

kernel/Kconfig.preempt

+13 −0
Original line number Diff line number Diff line
@@ -103,6 +103,19 @@ config PREEMPT_RT 
	  Select this if you are building a kernel for systems which

	  require real-time guarantees.



config PREEMPT_RT_NEEDS_BH_LOCK

	bool "Enforce softirq synchronisation on PREEMPT_RT"

	depends on PREEMPT_RT

	help

	  Enforce synchronisation across the softirqs context. On PREEMPT_RT

	  the softirq is preemptible. This enforces the same per-CPU BLK

	  semantic non-PREEMPT_RT builds have. This should not be needed

	  because per-CPU locks were added to avoid the per-CPU BKL.



	  This switch provides the old behaviour for testing reasons. Select

	  this if you suspect an error with preemptible softirq and want test

	  the old synchronized behaviour.



config PREEMPT_COUNT

       bool

kernel/irq/Kconfig

+2 −4
Original line number Diff line number Diff line
@@ -6,10 +6,6 @@ menu "IRQ subsystem" 
config MAY_HAVE_SPARSE_IRQ

       bool



# Legacy support, required for itanic

config GENERIC_IRQ_LEGACY

       bool



# Enable the generic irq autoprobe mechanism

config GENERIC_IRQ_PROBE

	bool
@@ -147,7 +143,9 @@ config GENERIC_IRQ_KEXEC_CLEAR_VM_FORWARD 
config IRQ_KUNIT_TEST

	bool "KUnit tests for IRQ management APIs" if !KUNIT_ALL_TESTS

	depends on KUNIT=y

	depends on SPARSE_IRQ

	default KUNIT_ALL_TESTS

	select IRQ_DOMAIN

	imply SMP

	help

	  This option enables KUnit tests for the IRQ subsystem API. These are

kernel/irq/chip.c

+37 −0
Original line number Diff line number Diff line
@@ -1259,6 +1259,43 @@ int irq_chip_get_parent_state(struct irq_data *data, 
}

EXPORT_SYMBOL_GPL(irq_chip_get_parent_state);



/**

 * irq_chip_shutdown_parent - Shutdown the parent interrupt

 * @data:	Pointer to interrupt specific data

 *

 * Invokes the irq_shutdown() callback of the parent if available or falls

 * back to irq_chip_disable_parent().

 */

void irq_chip_shutdown_parent(struct irq_data *data)

{

	struct irq_data *parent = data->parent_data;



	if (parent->chip->irq_shutdown)

		parent->chip->irq_shutdown(parent);

	else

		irq_chip_disable_parent(data);

}

EXPORT_SYMBOL_GPL(irq_chip_shutdown_parent);



/**

 * irq_chip_startup_parent - Startup the parent interrupt

 * @data:	Pointer to interrupt specific data

 *

 * Invokes the irq_startup() callback of the parent if available or falls

 * back to irq_chip_enable_parent().

 */

unsigned int irq_chip_startup_parent(struct irq_data *data)

{

	struct irq_data *parent = data->parent_data;



	if (parent->chip->irq_startup)

		return parent->chip->irq_startup(parent);



	irq_chip_enable_parent(data);

	return 0;

}

EXPORT_SYMBOL_GPL(irq_chip_startup_parent);



/**

 * irq_chip_enable_parent - Enable the parent interrupt (defaults to unmask if

 * NULL)