Commit 4001d8e8 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

genirq: Delay deactivation in free_irq() 



When interrupts are shutdown, they are immediately deactivated in the
irqdomain hierarchy. While this looks obviously correct there is a subtle
issue:

There might be an interrupt in flight when free_irq() is invoking the
shutdown. This is properly handled at the irq descriptor / primary handler
level, but the deactivation might completely disable resources which are
required to acknowledge the interrupt.

Split the shutdown code and deactivate the interrupt after synchronization
in free_irq(). Fixup all other usage sites where this is not an issue to
invoke the combined shutdown_and_deactivate() function instead.

This still might be an issue if the interrupt in flight servicing is
delayed on a remote CPU beyond the invocation of synchronize_irq(), but
that cannot be handled at that level and needs to be handled in the
synchronize_irq() context.

Fixes: f8264e34 ("irqdomain: Introduce new interfaces to support hierarchy irqdomains")
Reported-by: default avatarRobert Hodaszi <Robert.Hodaszi@digi.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/20190628111440.098196390@linutronix.de
parent c8c40767

kernel/irq/autoprobe.c

+3 −3
Original line number Diff line number Diff line
@@ -90,7 +90,7 @@ unsigned long probe_irq_on(void) 
			/* It triggered already - consider it spurious. */

			if (!(desc->istate & IRQS_WAITING)) {

				desc->istate &= ~IRQS_AUTODETECT;

				irq_shutdown(desc);

				irq_shutdown_and_deactivate(desc);

			} else

				if (i < 32)

					mask |= 1 << i;
@@ -127,7 +127,7 @@ unsigned int probe_irq_mask(unsigned long val) 
				mask |= 1 << i;



			desc->istate &= ~IRQS_AUTODETECT;

			irq_shutdown(desc);

			irq_shutdown_and_deactivate(desc);

		}

		raw_spin_unlock_irq(&desc->lock);

	}
@@ -169,7 +169,7 @@ int probe_irq_off(unsigned long val) 
				nr_of_irqs++;

			}

			desc->istate &= ~IRQS_AUTODETECT;

			irq_shutdown(desc);

			irq_shutdown_and_deactivate(desc);

		}

		raw_spin_unlock_irq(&desc->lock);

	}

kernel/irq/chip.c

+6 −0
Original line number Diff line number Diff line
@@ -314,6 +314,12 @@ void irq_shutdown(struct irq_desc *desc) 
		}

		irq_state_clr_started(desc);

	}

}





void irq_shutdown_and_deactivate(struct irq_desc *desc)

{

	irq_shutdown(desc);

	/*

	 * This must be called even if the interrupt was never started up,

	 * because the activation can happen before the interrupt is

kernel/irq/cpuhotplug.c

+1 −1
Original line number Diff line number Diff line
@@ -116,7 +116,7 @@ static bool migrate_one_irq(struct irq_desc *desc) 
		 */

		if (irqd_affinity_is_managed(d)) {

			irqd_set_managed_shutdown(d);

			irq_shutdown(desc);

			irq_shutdown_and_deactivate(desc);

			return false;

		}

		affinity = cpu_online_mask;

kernel/irq/internals.h

+1 −0
Original line number Diff line number Diff line
@@ -82,6 +82,7 @@ extern int irq_activate_and_startup(struct irq_desc *desc, bool resend); 
extern int irq_startup(struct irq_desc *desc, bool resend, bool force);



extern void irq_shutdown(struct irq_desc *desc);

extern void irq_shutdown_and_deactivate(struct irq_desc *desc);

extern void irq_enable(struct irq_desc *desc);

extern void irq_disable(struct irq_desc *desc);

extern void irq_percpu_enable(struct irq_desc *desc, unsigned int cpu);

kernel/irq/manage.c

+11 −1
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include <linux/module.h>

#include <linux/random.h>

#include <linux/interrupt.h>

#include <linux/irqdomain.h>

#include <linux/slab.h>

#include <linux/sched.h>

#include <linux/sched/rt.h>
@@ -1699,6 +1700,7 @@ static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id) 
	/* If this was the last handler, shut down the IRQ line: */

	if (!desc->action) {

		irq_settings_clr_disable_unlazy(desc);

		/* Only shutdown. Deactivate after synchronize_hardirq() */

		irq_shutdown(desc);

	}
@@ -1768,6 +1770,14 @@ static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id) 
		 * require it to deallocate resources over the slow bus.

		 */

		chip_bus_lock(desc);

		/*

		 * There is no interrupt on the fly anymore. Deactivate it

		 * completely.

		 */

		raw_spin_lock_irqsave(&desc->lock, flags);

		irq_domain_deactivate_irq(&desc->irq_data);

		raw_spin_unlock_irqrestore(&desc->lock, flags);



		irq_release_resources(desc);

		chip_bus_sync_unlock(desc);

		irq_remove_timings(desc);
@@ -1855,7 +1865,7 @@ static const void *__cleanup_nmi(unsigned int irq, struct irq_desc *desc) 
	}



	irq_settings_clr_disable_unlazy(desc);

	irq_shutdown(desc);

	irq_shutdown_and_deactivate(desc);



	irq_release_resources(desc);

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