[PATCH 18/39] irqdomain: Cache irq_data instead of a virq number in the revmap

From: Marc Zyngier
Date: Thu May 20 2021 - 12:57:23 EST


Caching a virq number in the revmap is pretty inefficient, as
it means we will need to convert it back to either an irq_data
or irq_desc to do anything with it.

It is also a bit odd, as the radix tree does cache irq_data
pointers.

Change the revmap type to be an irq_data pointer instead of
an unsigned int, and preserve the current API for now.

Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
include/linux/irqdomain.h | 4 ++--
kernel/irq/irqdomain.c | 16 +++++++++++-----
2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 0916cf9c6e20..340cc04611dd 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -151,7 +151,7 @@ struct irq_domain_chip_generic;
* Revmap data, used internally by irq_domain
* @revmap_size: Size of the linear map table @revmap[]
* @revmap_tree: Radix map tree for hwirqs that don't fit in the linear map
- * @revmap: Linear table of hwirq->virq reverse mappings
+ * @revmap: Linear table of irq_data pointers
*/
struct irq_domain {
struct list_head link;
@@ -174,7 +174,7 @@ struct irq_domain {
unsigned int revmap_size;
struct radix_tree_root revmap_tree;
struct mutex revmap_tree_mutex;
- unsigned int revmap[];
+ struct irq_data *revmap[];
};

/* Irq domain flags */
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index cdcb1989cd20..7a4e38804487 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -505,7 +505,7 @@ static void irq_domain_clear_mapping(struct irq_domain *domain,
return;

if (hwirq < domain->revmap_size) {
- domain->revmap[hwirq] = 0;
+ domain->revmap[hwirq] = NULL;
} else {
mutex_lock(&domain->revmap_tree_mutex);
radix_tree_delete(&domain->revmap_tree, hwirq);
@@ -521,7 +521,7 @@ static void irq_domain_set_mapping(struct irq_domain *domain,
return;

if (hwirq < domain->revmap_size) {
- domain->revmap[hwirq] = irq_data->irq;
+ domain->revmap[hwirq] = irq_data;
} else {
mutex_lock(&domain->revmap_tree_mutex);
radix_tree_insert(&domain->revmap_tree, hwirq, irq_data);
@@ -913,7 +913,7 @@ 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->revmap[hwirq];
+ return domain->revmap[hwirq]->irq;

rcu_read_lock();
data = radix_tree_lookup(&domain->revmap_tree, hwirq);
@@ -1496,8 +1496,14 @@ static void irq_domain_fix_revmap(struct irq_data *d)
{
void __rcu **slot;

- if (irq_domain_is_nomap(d->domain) || d->hwirq < d->domain->revmap_size)
- return; /* Not using radix tree. */
+ if (irq_domain_is_nomap(d->domain))
+ return;
+
+ if (d->hwirq < d->domain->revmap_size) {
+ /* Not using radix tree */
+ d->domain->revmap[d->hwirq] = d;
+ return;
+ }

/* Fix up the revmap. */
mutex_lock(&d->domain->revmap_tree_mutex);
--
2.30.2