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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: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2021-04-02 12:50:14 +01:00
parent 405e94e9ae
commit 1da027362a
2 changed files with 12 additions and 16 deletions
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22
include/linux/irqdomain.h
View File

@ -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;

6
kernel/irq/irqdomain.c
View File

@ -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);