[tip: irq/core] genirq: Use a maple tree for interrupt descriptor management
From: tip-bot2 for Shanker Donthineni
Date: Wed May 24 2023 - 06:02:00 EST
The following commit has been merged into the irq/core branch of tip:
Commit-ID: 721255b9826bd11c7a38b585905fc2dd0fb94e52
Gitweb: https://git.kernel.org/tip/721255b9826bd11c7a38b585905fc2dd0fb94e52
Author: Shanker Donthineni <sdonthineni@xxxxxxxxxx>
AuthorDate: Fri, 19 May 2023 08:49:02 -05:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Wed, 24 May 2023 11:39:44 +02:00
genirq: Use a maple tree for interrupt descriptor management
The current implementation uses a static bitmap for interrupt descriptor
allocation and a radix tree to pointer store the pointer for lookup.
However, the size of the bitmap is constrained by the build time macro
MAX_SPARSE_IRQS, which may not be sufficient to support high-end servers,
particularly those with GICv4.1 hardware, which require a large interrupt
space to cover LPIs and vSGIs.
Replace the bitmap and the radix tree with a maple tree, which not only
stores pointers for lookup, but also provides a mechanism to find free
ranges. That removes the build time hardcoded upper limit.
Signed-off-by: Shanker Donthineni <sdonthineni@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230519134902.1495562-4-sdonthineni@xxxxxxxxxx
---
kernel/irq/internals.h | 2 +-
kernel/irq/irqdesc.c | 57 +++++++++++++++++++++++------------------
2 files changed, 33 insertions(+), 26 deletions(-)
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index f3f2090..7bdb750 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -12,7 +12,7 @@
#include <linux/sched/clock.h>
#ifdef CONFIG_SPARSE_IRQ
-# define MAX_SPARSE_IRQS (NR_IRQS + 8196)
+# define MAX_SPARSE_IRQS INT_MAX
#else
# define MAX_SPARSE_IRQS NR_IRQS
#endif
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index e0d9dd9..27ca1c8 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -12,8 +12,7 @@
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
-#include <linux/radix-tree.h>
-#include <linux/bitmap.h>
+#include <linux/maple_tree.h>
#include <linux/irqdomain.h>
#include <linux/sysfs.h>
@@ -131,17 +130,39 @@ int nr_irqs = NR_IRQS;
EXPORT_SYMBOL_GPL(nr_irqs);
static DEFINE_MUTEX(sparse_irq_lock);
-static DECLARE_BITMAP(allocated_irqs, MAX_SPARSE_IRQS);
+static struct maple_tree sparse_irqs = MTREE_INIT_EXT(sparse_irqs,
+ MT_FLAGS_ALLOC_RANGE |
+ MT_FLAGS_LOCK_EXTERN |
+ MT_FLAGS_USE_RCU,
+ sparse_irq_lock);
static int irq_find_free_area(unsigned int from, unsigned int cnt)
{
- return bitmap_find_next_zero_area(allocated_irqs, MAX_SPARSE_IRQS,
- from, cnt, 0);
+ MA_STATE(mas, &sparse_irqs, 0, 0);
+
+ if (mas_empty_area(&mas, from, MAX_SPARSE_IRQS, cnt))
+ return -ENOSPC;
+ return mas.index;
}
static unsigned int irq_find_at_or_after(unsigned int offset)
{
- return find_next_bit(allocated_irqs, nr_irqs, offset);
+ unsigned long index = offset;
+ struct irq_desc *desc = mt_find(&sparse_irqs, &index, nr_irqs);
+
+ return desc ? irq_desc_get_irq(desc) : nr_irqs;
+}
+
+static void irq_insert_desc(unsigned int irq, struct irq_desc *desc)
+{
+ MA_STATE(mas, &sparse_irqs, irq, irq);
+ WARN_ON(mas_store_gfp(&mas, desc, GFP_KERNEL) != 0);
+}
+
+static void delete_irq_desc(unsigned int irq)
+{
+ MA_STATE(mas, &sparse_irqs, irq, irq);
+ mas_erase(&mas);
}
#ifdef CONFIG_SPARSE_IRQ
@@ -355,26 +376,14 @@ static void irq_sysfs_del(struct irq_desc *desc) {}
#endif /* CONFIG_SYSFS */
-static RADIX_TREE(irq_desc_tree, GFP_KERNEL);
-
-static void irq_insert_desc(unsigned int irq, struct irq_desc *desc)
-{
- radix_tree_insert(&irq_desc_tree, irq, desc);
-}
-
struct irq_desc *irq_to_desc(unsigned int irq)
{
- return radix_tree_lookup(&irq_desc_tree, irq);
+ return mtree_load(&sparse_irqs, irq);
}
#ifdef CONFIG_KVM_BOOK3S_64_HV_MODULE
EXPORT_SYMBOL_GPL(irq_to_desc);
#endif
-static void delete_irq_desc(unsigned int irq)
-{
- radix_tree_delete(&irq_desc_tree, irq);
-}
-
#ifdef CONFIG_SMP
static void free_masks(struct irq_desc *desc)
{
@@ -517,7 +526,6 @@ static int alloc_descs(unsigned int start, unsigned int cnt, int node,
irq_sysfs_add(start + i, desc);
irq_add_debugfs_entry(start + i, desc);
}
- bitmap_set(allocated_irqs, start, cnt);
return start;
err:
@@ -557,7 +565,6 @@ int __init early_irq_init(void)
for (i = 0; i < initcnt; i++) {
desc = alloc_desc(i, node, 0, NULL, NULL);
- set_bit(i, allocated_irqs);
irq_insert_desc(i, desc);
}
return arch_early_irq_init();
@@ -612,6 +619,7 @@ static void free_desc(unsigned int irq)
raw_spin_lock_irqsave(&desc->lock, flags);
desc_set_defaults(irq, desc, irq_desc_get_node(desc), NULL, NULL);
raw_spin_unlock_irqrestore(&desc->lock, flags);
+ delete_irq_desc(irq);
}
static inline int alloc_descs(unsigned int start, unsigned int cnt, int node,
@@ -624,8 +632,8 @@ static inline int alloc_descs(unsigned int start, unsigned int cnt, int node,
struct irq_desc *desc = irq_to_desc(start + i);
desc->owner = owner;
+ irq_insert_desc(start + i, desc);
}
- bitmap_set(allocated_irqs, start, cnt);
return start;
}
@@ -637,7 +645,7 @@ static int irq_expand_nr_irqs(unsigned int nr)
void irq_mark_irq(unsigned int irq)
{
mutex_lock(&sparse_irq_lock);
- bitmap_set(allocated_irqs, irq, 1);
+ irq_insert_desc(irq, irq_desc + irq);
mutex_unlock(&sparse_irq_lock);
}
@@ -781,7 +789,6 @@ void irq_free_descs(unsigned int from, unsigned int cnt)
for (i = 0; i < cnt; i++)
free_desc(from + i);
- bitmap_clear(allocated_irqs, from, cnt);
mutex_unlock(&sparse_irq_lock);
}
EXPORT_SYMBOL_GPL(irq_free_descs);
@@ -844,7 +851,7 @@ EXPORT_SYMBOL_GPL(__irq_alloc_descs);
* irq_get_next_irq - get next allocated irq number
* @offset: where to start the search
*
- * Returns next irq number at or after offset or nr_irqs if none is found.
+ * Returns next irq number after offset or nr_irqs if none is found.
*/
unsigned int irq_get_next_irq(unsigned int offset)
{