Commit a304e1b8 authored by David Woodhouse's avatar David Woodhouse Committed by Linus Torvalds
Browse files

[PATCH] Debug shared irqs 



Drivers registering IRQ handlers with SA_SHIRQ really ought to be able to
handle an interrupt happening before request_irq() returns.  They also
ought to be able to handle an interrupt happening during the start of their
call to free_irq().  Let's test that hypothesis....

[bunk@stusta.de: Kconfig fixes]
Signed-off-by: default avatarDavid Woodhouse <dwmw2@infradead.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: default avatarJesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAdrian Bunk <bunk@stusta.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f9e4acf3

kernel/irq/manage.c

+33 −0
Original line number Diff line number Diff line
@@ -357,6 +357,7 @@ void free_irq(unsigned int irq, void *dev_id) 
	struct irq_desc *desc;

	struct irqaction **p;

	unsigned long flags;

	irqreturn_t (*handler)(int, void *) = NULL;



	WARN_ON(in_interrupt());

	if (irq >= NR_IRQS)
@@ -396,6 +397,8 @@ void free_irq(unsigned int irq, void *dev_id) 


			/* Make sure it's not being used on another CPU */

			synchronize_irq(irq);

			if (action->flags & IRQF_SHARED)

				handler = action->handler;

			kfree(action);

			return;

		}
@@ -403,6 +406,17 @@ void free_irq(unsigned int irq, void *dev_id) 
		spin_unlock_irqrestore(&desc->lock, flags);

		return;

	}

#ifdef CONFIG_DEBUG_SHIRQ

	if (handler) {

		/*

		 * It's a shared IRQ -- the driver ought to be prepared for it

		 * to happen even now it's being freed, so let's make sure....

		 * We do this after actually deregistering it, to make sure that

		 * a 'real' IRQ doesn't run in parallel with our fake

		 */

		handler(irq, dev_id);

	}

#endif

}

EXPORT_SYMBOL(free_irq);
@@ -475,6 +489,25 @@ int request_irq(unsigned int irq, irq_handler_t handler, 


	select_smp_affinity(irq);



#ifdef CONFIG_DEBUG_SHIRQ

	if (irqflags & IRQF_SHARED) {

		/*

		 * It's a shared IRQ -- the driver ought to be prepared for it

		 * to happen immediately, so let's make sure....

		 * We do this before actually registering it, to make sure that

		 * a 'real' IRQ doesn't run in parallel with our fake

		 */

		if (irqflags & IRQF_DISABLED) {

			unsigned long flags;



			local_irq_save(flags);

			handler(irq, dev_id);

			local_irq_restore(flags);

		} else

			handler(irq, dev_id);

	}

#endif



	retval = setup_irq(irq, action);

	if (retval)

		kfree(action);

lib/Kconfig.debug

+9 −0
Original line number Diff line number Diff line
@@ -77,6 +77,15 @@ config DEBUG_KERNEL 
	  Say Y here if you are developing drivers or trying to debug and

	  identify kernel problems.



config DEBUG_SHIRQ

	bool "Debug shared IRQ handlers"

	depends on DEBUG_KERNEL && GENERIC_HARDIRQS

	help

	  Enable this to generate a spurious interrupt as soon as a shared

	  interrupt handler is registered, and just before one is deregistered.

	  Drivers ought to be able to handle interrupts coming in at those

	  points; some don't and need to be caught.



config LOG_BUF_SHIFT

	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL

	range 12 21

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