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Commit ae88a23b authored by Ingo Molnar's avatar Ingo Molnar
Browse files

irq: refactor and clean up the free_irq() code flow 



Impact: cleanup

- separate out the loop from the actual freeing logic, this wins us
  two indentation levels allowing a number of followup prettifications

- turn the WARN_ON() into a more informative WARN().

- clean up the comments and the code flow some more

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 327ec569

kernel/irq/manage.c

+54 −47
Original line number Diff line number Diff line
@@ -575,35 +575,49 @@ int setup_irq(unsigned int irq, struct irqaction *act) 
void free_irq(unsigned int irq, void *dev_id)

{

	struct irq_desc *desc = irq_to_desc(irq);

	struct irqaction **p;

	struct irqaction *action, **p, **pp;

	unsigned long flags;



	WARN_ON(in_interrupt());

	WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);



	if (!desc)

		return;



	spin_lock_irqsave(&desc->lock, flags);



	/*

	 * There can be multiple actions per IRQ descriptor, find the right

	 * one based on the dev_id:

	 */

	p = &desc->action;

	for (;;) {

		struct irqaction *action = *p;

		action = *p;

		pp = p;



		if (action) {

			struct irqaction **pp = p;

		if (!action) {

			WARN(1, "Trying to free already-free IRQ %d\n", irq);

			spin_unlock_irqrestore(&desc->lock, flags);



			return;

		}



		p = &action->next;

		if (action->dev_id != dev_id)

			continue;



			/* Found it - now remove it from the list of entries */

		break;

	}



	/* Found it - now remove it from the list of entries: */

	*pp = action->next;



			/* Currently used only by UML, might disappear one day.*/

	/* Currently used only by UML, might disappear one day: */

#ifdef CONFIG_IRQ_RELEASE_METHOD

	if (desc->chip->release)

		desc->chip->release(irq, dev_id);

#endif



	/* If this was the last handler, shut down the IRQ line: */

	if (!desc->action) {

		desc->status |= IRQ_DISABLED;

		if (desc->chip->shutdown)
@@ -612,18 +626,20 @@ void free_irq(unsigned int irq, void *dev_id) 
			desc->chip->disable(irq);

	}

	spin_unlock_irqrestore(&desc->lock, flags);



	unregister_handler_proc(irq, action);



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

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

	synchronize_irq(irq);



#ifdef CONFIG_DEBUG_SHIRQ

	/*

			 * 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

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

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

	 * is so by doing an extra call to the handler ....

	 *

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

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

	 */

	if (action->flags & IRQF_SHARED) {

		local_irq_save(flags);
@@ -632,15 +648,6 @@ void free_irq(unsigned int irq, void *dev_id) 
	}

#endif

	kfree(action);

			return;

		}

		printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);

#ifdef CONFIG_DEBUG_SHIRQ

		dump_stack();

#endif

		spin_unlock_irqrestore(&desc->lock, flags);

		return;

	}

}

EXPORT_SYMBOL(free_irq);