[PATCH v5 2/3] genirq: Encapsulate sparse bitmap handling

From: Shanker Donthineni
Date: Fri May 19 2023 - 09:49:45 EST


Move the open coded sparse bitmap handling into helper functions as
a preparatory step for converting the sparse interrupt management
to a maple tree.

No functional change.

Signed-off-by: Shanker Donthineni <sdonthineni@xxxxxxxxxx>
---
kernel/irq/internals.h | 4 ++--
kernel/irq/irqdesc.c | 30 ++++++++++++++++++++----------
2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index 51fc8c497c22..f3f2090dd2de 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -12,9 +12,9 @@
#include <linux/sched/clock.h>

#ifdef CONFIG_SPARSE_IRQ
-# define IRQ_BITMAP_BITS (NR_IRQS + 8196)
+# define MAX_SPARSE_IRQS (NR_IRQS + 8196)
#else
-# define IRQ_BITMAP_BITS NR_IRQS
+# define MAX_SPARSE_IRQS NR_IRQS
#endif

#define istate core_internal_state__do_not_mess_with_it
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index b401b89b226a..e0d9dd9b36f9 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -131,7 +131,18 @@ int nr_irqs = NR_IRQS;
EXPORT_SYMBOL_GPL(nr_irqs);

static DEFINE_MUTEX(sparse_irq_lock);
-static DECLARE_BITMAP(allocated_irqs, IRQ_BITMAP_BITS);
+static DECLARE_BITMAP(allocated_irqs, MAX_SPARSE_IRQS);
+
+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);
+}
+
+static unsigned int irq_find_at_or_after(unsigned int offset)
+{
+ return find_next_bit(allocated_irqs, nr_irqs, offset);
+}

#ifdef CONFIG_SPARSE_IRQ

@@ -517,7 +528,7 @@ static int alloc_descs(unsigned int start, unsigned int cnt, int node,

static int irq_expand_nr_irqs(unsigned int nr)
{
- if (nr > IRQ_BITMAP_BITS)
+ if (nr > MAX_SPARSE_IRQS)
return -ENOMEM;
nr_irqs = nr;
return 0;
@@ -535,11 +546,11 @@ int __init early_irq_init(void)
printk(KERN_INFO "NR_IRQS: %d, nr_irqs: %d, preallocated irqs: %d\n",
NR_IRQS, nr_irqs, initcnt);

- if (WARN_ON(nr_irqs > IRQ_BITMAP_BITS))
- nr_irqs = IRQ_BITMAP_BITS;
+ if (WARN_ON(nr_irqs > MAX_SPARSE_IRQS))
+ nr_irqs = MAX_SPARSE_IRQS;

- if (WARN_ON(initcnt > IRQ_BITMAP_BITS))
- initcnt = IRQ_BITMAP_BITS;
+ if (WARN_ON(initcnt > MAX_SPARSE_IRQS))
+ initcnt = MAX_SPARSE_IRQS;

if (initcnt > nr_irqs)
nr_irqs = initcnt;
@@ -812,8 +823,7 @@ __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,

mutex_lock(&sparse_irq_lock);

- start = bitmap_find_next_zero_area(allocated_irqs, IRQ_BITMAP_BITS,
- from, cnt, 0);
+ start = irq_find_free_area(from, cnt);
ret = -EEXIST;
if (irq >=0 && start != irq)
goto unlock;
@@ -834,11 +844,11 @@ 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 after offset or nr_irqs if none is found.
+ * Returns next irq number at or after offset or nr_irqs if none is found.
*/
unsigned int irq_get_next_irq(unsigned int offset)
{
- return find_next_bit(allocated_irqs, nr_irqs, offset);
+ return irq_find_at_or_after(offset);
}

struct irq_desc *
--
2.25.1