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Date: Wed, 11 Apr 2012 17:18:45 -0600
From: Grant Likely <grant.likely@...retlab.ca>
To: linux-kernel@...r.kernel.org
Cc: Grant Likely <grant.likely@...retlab.ca>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Thomas Gleixner <tglx@...utronix.de>,
Milton Miller <miltonm@....com>
Subject: [PATCH 2/3] irq_domain: eliminate slow-path revmap lookups
With the current state of irq_domain, the reverse map is always updated
when new IRQs get mapped. This means that the irq_find_mapping() function
can be simplified to always execute the revmap-specific lookup function.
This patch adds lookup functions for the revmaps that don't yet have one
and removes the slow path lookup code path.
v6: Remove the slow path entirely. The only place where the slow path
could get called is for a linear mapping if the hwirq number is larger
than the linear revmap size.
v5: rewrite to not use a ->revmap() callback. It is simpler, smaller,
safer and faster to open code each of the revmap lookups directly into
irq_find_mapping() via a switch statement.
v4: Fix build failure on incorrect variable reference.
Signed-off-by: Grant Likely <grant.likely@...retlab.ca>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Milton Miller <miltonm@....com>
---
arch/powerpc/sysdev/xics/icp-hv.c | 2 +-
arch/powerpc/sysdev/xics/icp-native.c | 2 +-
arch/powerpc/sysdev/xics/xics-common.c | 3 -
include/linux/irqdomain.h | 4 -
kernel/irq/irqdomain.c | 129 ++++++++++----------------------
5 files changed, 43 insertions(+), 97 deletions(-)
diff --git a/arch/powerpc/sysdev/xics/icp-hv.c b/arch/powerpc/sysdev/xics/icp-hv.c
index 253dce9..14469cf 100644
--- a/arch/powerpc/sysdev/xics/icp-hv.c
+++ b/arch/powerpc/sysdev/xics/icp-hv.c
@@ -111,7 +111,7 @@ static unsigned int icp_hv_get_irq(void)
if (vec == XICS_IRQ_SPURIOUS)
return NO_IRQ;
- irq = irq_radix_revmap_lookup(xics_host, vec);
+ irq = irq_find_mapping(xics_host, vec);
if (likely(irq != NO_IRQ)) {
xics_push_cppr(vec);
return irq;
diff --git a/arch/powerpc/sysdev/xics/icp-native.c b/arch/powerpc/sysdev/xics/icp-native.c
index 4c79b6f..48861d3 100644
--- a/arch/powerpc/sysdev/xics/icp-native.c
+++ b/arch/powerpc/sysdev/xics/icp-native.c
@@ -119,7 +119,7 @@ static unsigned int icp_native_get_irq(void)
if (vec == XICS_IRQ_SPURIOUS)
return NO_IRQ;
- irq = irq_radix_revmap_lookup(xics_host, vec);
+ irq = irq_find_mapping(xics_host, vec);
if (likely(irq != NO_IRQ)) {
xics_push_cppr(vec);
return irq;
diff --git a/arch/powerpc/sysdev/xics/xics-common.c b/arch/powerpc/sysdev/xics/xics-common.c
index ea5e204..1d7067d 100644
--- a/arch/powerpc/sysdev/xics/xics-common.c
+++ b/arch/powerpc/sysdev/xics/xics-common.c
@@ -330,9 +330,6 @@ static int xics_host_map(struct irq_domain *h, unsigned int virq,
pr_devel("xics: map virq %d, hwirq 0x%lx\n", virq, hw);
- /* Insert the interrupt mapping into the radix tree for fast lookup */
- irq_radix_revmap_insert(xics_host, virq, hw);
-
/* They aren't all level sensitive but we just don't really know */
irq_set_status_flags(virq, IRQ_LEVEL);
diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index ac17b9b..7a7af17 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -149,10 +149,6 @@ extern void irq_dispose_mapping(unsigned int virq);
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 void irq_radix_revmap_insert(struct irq_domain *host, unsigned int virq,
- irq_hw_number_t hwirq);
-extern unsigned int irq_radix_revmap_lookup(struct irq_domain *host,
- irq_hw_number_t hwirq);
extern unsigned int irq_linear_revmap(struct irq_domain *host,
irq_hw_number_t hwirq);
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 041710d..df92a34 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -314,7 +314,8 @@ unsigned int irq_create_direct_mapping(struct irq_domain *domain)
domain = irq_default_domain;
BUG_ON(domain == NULL);
- WARN_ON(domain->revmap_type != IRQ_DOMAIN_MAP_NOMAP);
+ if (WARN_ON(domain->revmap_type != IRQ_DOMAIN_MAP_NOMAP))
+ return 0;
virq = irq_alloc_desc_from(1, 0);
if (!virq) {
@@ -385,11 +386,22 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
}
if (irq_setup_virq(domain, virq, hwirq)) {
- if (domain->revmap_type != IRQ_DOMAIN_MAP_LEGACY)
- irq_free_desc(virq);
+ irq_free_desc(virq);
return 0;
}
+ switch(domain->revmap_type) {
+ case IRQ_DOMAIN_MAP_LINEAR:
+ if (hwirq < domain->revmap_data.linear.size)
+ domain->revmap_data.linear.revmap[hwirq] = virq;
+ break;
+ case IRQ_DOMAIN_MAP_TREE:
+ mutex_lock(&revmap_trees_mutex);
+ radix_tree_insert(&domain->revmap_data.tree, hwirq,
+ irq_get_irq_data(virq));
+ mutex_unlock(&revmap_trees_mutex);
+ break;
+ }
pr_debug("irq: irq %lu on domain %s mapped to virtual irq %u\n",
hwirq, domain->of_node ? domain->of_node->full_name : "null", virq);
@@ -510,8 +522,7 @@ EXPORT_SYMBOL_GPL(irq_dispose_mapping);
unsigned int irq_find_mapping(struct irq_domain *domain,
irq_hw_number_t hwirq)
{
- unsigned int i;
- struct irq_desc *desc;
+ struct irq_data *data;
/* Look for default domain if nececssary */
if (domain == NULL)
@@ -519,107 +530,49 @@ unsigned int irq_find_mapping(struct irq_domain *domain,
if (domain == NULL)
return 0;
- /* legacy -> bail early */
- if (domain->revmap_type == IRQ_DOMAIN_MAP_LEGACY)
+ switch (domain->revmap_type) {
+ case IRQ_DOMAIN_MAP_LEGACY:
return irq_domain_legacy_revmap(domain, hwirq);
-
- /* Slow path does a linear search of the map */
- for_each_irq_desc(i, desc) {
- struct irq_data *data = irq_get_irq_data(i);
+ case IRQ_DOMAIN_MAP_LINEAR:
+ return irq_linear_revmap(domain, hwirq);
+ case IRQ_DOMAIN_MAP_TREE:
+ rcu_read_lock();
+ data = radix_tree_lookup(&domain->revmap_data.tree, hwirq);
+ rcu_read_unlock();
+ if (data)
+ return data->irq;
+ break;
+ case IRQ_DOMAIN_MAP_NOMAP:
+ data = irq_get_irq_data(hwirq);
if (data && (data->domain == domain) && (data->hwirq == hwirq))
- return i;
+ return hwirq;
+ break;
}
+
+ WARN(1, "ERROR: irq revmap went horribly wrong. revmap_type=%i\n",
+ domain->revmap_type);
return 0;
}
EXPORT_SYMBOL_GPL(irq_find_mapping);
/**
- * irq_radix_revmap_lookup() - 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, for use by irq controller code that uses radix tree
- * revmaps
- */
-unsigned int irq_radix_revmap_lookup(struct irq_domain *domain,
- irq_hw_number_t hwirq)
-{
- struct irq_data *irq_data;
-
- if (WARN_ON_ONCE(domain->revmap_type != IRQ_DOMAIN_MAP_TREE))
- return irq_find_mapping(domain, hwirq);
-
- /*
- * Freeing an irq can delete nodes along the path to
- * do the lookup via call_rcu.
- */
- rcu_read_lock();
- irq_data = radix_tree_lookup(&domain->revmap_data.tree, hwirq);
- rcu_read_unlock();
-
- /*
- * If found in radix tree, then fine.
- * Else fallback to linear lookup - this should not happen in practice
- * as it means that we failed to insert the node in the radix tree.
- */
- return irq_data ? irq_data->irq : irq_find_mapping(domain, hwirq);
-}
-
-/**
- * irq_radix_revmap_insert() - Insert a hw irq to linux irq number mapping.
- * @domain: domain owning this hardware interrupt
- * @virq: linux irq number
- * @hwirq: hardware irq number in that domain space
- *
- * This is for use by irq controllers that use a radix tree reverse
- * mapping for fast lookup.
- */
-void irq_radix_revmap_insert(struct irq_domain *domain, unsigned int virq,
- irq_hw_number_t hwirq)
-{
- struct irq_data *irq_data = irq_get_irq_data(virq);
-
- if (WARN_ON(domain->revmap_type != IRQ_DOMAIN_MAP_TREE))
- return;
-
- if (virq) {
- mutex_lock(&revmap_trees_mutex);
- radix_tree_insert(&domain->revmap_data.tree, hwirq, irq_data);
- mutex_unlock(&revmap_trees_mutex);
- }
-}
-
-/**
* irq_linear_revmap() - 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, for use by irq controller code that uses linear
- * revmaps. It does fallback to the slow path if the revmap doesn't exist
- * yet and will create the revmap entry with appropriate locking
+ * This is a fast path that can be called directly by irq controller code to
+ * save a handful of instructions.
*/
unsigned int irq_linear_revmap(struct irq_domain *domain,
irq_hw_number_t hwirq)
{
- unsigned int *revmap;
-
- if (WARN_ON_ONCE(domain->revmap_type != IRQ_DOMAIN_MAP_LINEAR))
- return irq_find_mapping(domain, hwirq);
+ BUG_ON(domain->revmap_type != IRQ_DOMAIN_MAP_LINEAR);
- /* Check revmap bounds */
- if (unlikely(hwirq >= domain->revmap_data.linear.size))
- return irq_find_mapping(domain, hwirq);
-
- /* Check if revmap was allocated */
- revmap = domain->revmap_data.linear.revmap;
- if (unlikely(revmap == NULL))
- return irq_find_mapping(domain, hwirq);
-
- /* Fill up revmap with slow path if no mapping found */
- if (unlikely(!revmap[hwirq]))
- revmap[hwirq] = irq_find_mapping(domain, hwirq);
+ /* Check revmap bounds; complain if exceeded */
+ if (WARN_ON(hwirq >= domain->revmap_data.linear.size))
+ return 0;
- return revmap[hwirq];
+ return domain->revmap_data.linear.revmap[hwirq];
}
#ifdef CONFIG_IRQ_DOMAIN_DEBUG
--
1.7.9.1
--
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