Commit 1da02736 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

irqdomain: Reimplement irq_linear_revmap() with irq_find_mapping() 



irq_linear_revmap() is supposed to be a fast path for domain
lookups, but it only exposes low-level details of the irqdomain
implementation, details which are better kept private.

The *overhead* between the two is only a function call and
a couple of tests, so it is likely that noone can show any
meaningful difference compared to the cost of taking an
interrupt.

Reimplement irq_linear_revmap() with irq_find_mapping()
in order to preserve source code compatibility, and
rename the internal field for a measure.

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 405e94e9

include/linux/irqdomain.h

+9 −13
Original line number Diff line number Diff line
@@ -151,9 +151,9 @@ struct irq_domain_chip_generic; 
 * Revmap data, used internally by irq_domain

 * @revmap_direct_max_irq: The largest hwirq that can be set for controllers that

 *                         support direct mapping

 * @revmap_size: Size of the linear map table @linear_revmap[]

 * @revmap_size: Size of the linear map table @revmap[]

 * @revmap_tree: Radix map tree for hwirqs that don't fit in the linear map

 * @linear_revmap: Linear table of hwirq->virq reverse mappings

 * @revmap: Linear table of hwirq->virq reverse mappings

 */

struct irq_domain {

	struct list_head link;
@@ -177,7 +177,7 @@ struct irq_domain { 
	unsigned int revmap_size;

	struct radix_tree_root revmap_tree;

	struct mutex revmap_tree_mutex;

	unsigned int linear_revmap[];

	unsigned int revmap[];

};



/* Irq domain flags */
@@ -394,24 +394,20 @@ static inline unsigned int irq_create_mapping(struct irq_domain *host, 
	return irq_create_mapping_affinity(host, hwirq, NULL);

}





/**

 * irq_linear_revmap() - Find a linux irq from a hw irq number.

 * irq_find_mapping() - Find a linux irq from a hw irq number.

 * @domain: domain owning this hardware interrupt

 * @hwirq: hardware irq number in that domain space

 *

 * This is a fast path alternative to irq_find_mapping() that can be

 * called directly by irq controller code to save a handful of

 * instructions. It is always safe to call, but won't find irqs mapped

 * using the radix tree.

 */

extern unsigned int irq_find_mapping(struct irq_domain *host,

				     irq_hw_number_t hwirq);



static inline unsigned int irq_linear_revmap(struct irq_domain *domain,

					     irq_hw_number_t hwirq)

{

	return hwirq < domain->revmap_size ? domain->linear_revmap[hwirq] : 0;

	return irq_find_mapping(domain, hwirq);

}

extern unsigned int irq_find_mapping(struct irq_domain *host,

				     irq_hw_number_t hwirq);



extern unsigned int irq_create_direct_mapping(struct irq_domain *host);



extern const struct irq_domain_ops irq_domain_simple_ops;

kernel/irq/irqdomain.c

+3 −3
Original line number Diff line number Diff line
@@ -486,7 +486,7 @@ static void irq_domain_clear_mapping(struct irq_domain *domain, 
				     irq_hw_number_t hwirq)

{

	if (hwirq < domain->revmap_size) {

		domain->linear_revmap[hwirq] = 0;

		domain->revmap[hwirq] = 0;

	} else {

		mutex_lock(&domain->revmap_tree_mutex);

		radix_tree_delete(&domain->revmap_tree, hwirq);
@@ -499,7 +499,7 @@ static void irq_domain_set_mapping(struct irq_domain *domain, 
				   struct irq_data *irq_data)

{

	if (hwirq < domain->revmap_size) {

		domain->linear_revmap[hwirq] = irq_data->irq;

		domain->revmap[hwirq] = irq_data->irq;

	} else {

		mutex_lock(&domain->revmap_tree_mutex);

		radix_tree_insert(&domain->revmap_tree, hwirq, irq_data);
@@ -885,7 +885,7 @@ unsigned int irq_find_mapping(struct irq_domain *domain, 


	/* Check if the hwirq is in the linear revmap. */

	if (hwirq < domain->revmap_size)

		return domain->linear_revmap[hwirq];

		return domain->revmap[hwirq];



	rcu_read_lock();

	data = radix_tree_lookup(&domain->revmap_tree, hwirq);