[patch V4 08/15] genirq: Expose nr_irqs in core code

Thomas Gleixner
2026-03-31T07:26:09Z

... to avoid function calls in the core code to retrieve the maximum number
of interrupts.

Rename it to 'total_nr_irqs' as 'nr_irqs' is too generic and fix up the
'nr_irqs' reference in the related GDB script as well.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
---
V3: Fix up the missing usage sites and gdb script - Radu
---
kernel/irq/internals.h | 1 +
kernel/irq/irqdesc.c | 28 ++++++++++++++--------------
kernel/irq/proc.c | 4 ++--
scripts/gdb/linux/interrupts.py | 2 +-
4 files changed, 18 insertions(+), 17 deletions(-)
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -21,6 +21,7 @@

extern bool noirqdebug;
extern int irq_poll_cpu;
+extern unsigned int total_nr_irqs;

extern struct irqaction chained_action;

--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -140,14 +140,14 @@ static void desc_set_defaults(unsigned i
desc_smp_init(desc, node, affinity);
}

-static unsigned int nr_irqs = NR_IRQS;
+unsigned int total_nr_irqs __read_mostly = NR_IRQS;

/**
* irq_get_nr_irqs() - Number of interrupts supported by the system.
*/
unsigned int irq_get_nr_irqs(void)
{
- return nr_irqs;
+ return total_nr_irqs;
}
EXPORT_SYMBOL_GPL(irq_get_nr_irqs);

@@ -159,7 +159,7 @@ EXPORT_SYMBOL_GPL(irq_get_nr_irqs);
*/
unsigned int irq_set_nr_irqs(unsigned int nr)
{
- nr_irqs = nr;
+ total_nr_irqs = nr;

return nr;
}
@@ -187,9 +187,9 @@ static unsigned int irq_find_at_or_after
struct irq_desc *desc;

guard(rcu)();
- desc = mt_find(&sparse_irqs, &index, nr_irqs);
+ desc = mt_find(&sparse_irqs, &index, total_nr_irqs);

- return desc ? irq_desc_get_irq(desc) : nr_irqs;
+ return desc ? irq_desc_get_irq(desc) : total_nr_irqs;
}

static void irq_insert_desc(unsigned int irq, struct irq_desc *desc)
@@ -543,7 +543,7 @@ static bool irq_expand_nr_irqs(unsigned
{
if (nr > MAX_SPARSE_IRQS)
return false;
- nr_irqs = nr;
+ total_nr_irqs = nr;
return true;
}

@@ -557,16 +557,16 @@ int __init early_irq_init(void)
/* Let arch update nr_irqs and return the nr of preallocated irqs */
initcnt = arch_probe_nr_irqs();
printk(KERN_INFO "NR_IRQS: %d, nr_irqs: %d, preallocated irqs: %d\n",
- NR_IRQS, nr_irqs, initcnt);
+ NR_IRQS, total_nr_irqs, initcnt);

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

if (WARN_ON(initcnt > MAX_SPARSE_IRQS))
initcnt = MAX_SPARSE_IRQS;

- if (initcnt > nr_irqs)
- nr_irqs = initcnt;
+ if (initcnt > total_nr_irqs)
+ total_nr_irqs = initcnt;

for (i = 0; i < initcnt; i++) {
desc = alloc_desc(i, node, 0, NULL, NULL);
@@ -862,7 +862,7 @@ void irq_free_descs(unsigned int from, u
{
int i;

- if (from >= nr_irqs || (from + cnt) > nr_irqs)
+ if (from >= total_nr_irqs || (from + cnt) > total_nr_irqs)
return;

guard(mutex)(&sparse_irq_lock);
@@ -911,7 +911,7 @@ int __ref __irq_alloc_descs(int irq, uns
if (irq >=0 && start != irq)
return -EEXIST;

- if (start + cnt > nr_irqs) {
+ if (start + cnt > total_nr_irqs) {
if (!irq_expand_nr_irqs(start + cnt))
return -ENOMEM;
}
@@ -923,7 +923,7 @@ 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 after offset or nr_irqs if none is found.
+ * Returns next irq number after offset or total_nr_irqs if none is found.
*/
unsigned int irq_get_next_irq(unsigned int offset)
{
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -447,7 +447,7 @@ int __weak arch_show_interrupts(struct s
}

#ifndef ACTUAL_NR_IRQS
-# define ACTUAL_NR_IRQS irq_get_nr_irqs()
+# define ACTUAL_NR_IRQS total_nr_irqs
#endif

#define ZSTR1 " 0"
@@ -488,7 +488,7 @@ void irq_proc_emit_counts(struct seq_fil

int show_interrupts(struct seq_file *p, void *v)
{
- const unsigned int nr_irqs = irq_get_nr_irqs();
+ const unsigned int nr_irqs = total_nr_irqs;
static int prec;

int i = *(loff_t *) v, j;
--- a/scripts/gdb/linux/interrupts.py
+++ b/scripts/gdb/linux/interrupts.py
@@ -174,7 +174,7 @@ irq_desc_type = utils.CachedType("struct
super(LxInterruptList, self).__init__("lx-interruptlist", gdb.COMMAND_DATA)

def invoke(self, arg, from_tty):
- nr_irqs = gdb.parse_and_eval("nr_irqs")
+ nr_irqs = gdb.parse_and_eval("total_nr_irqs")
prec = 3
j = 1000
while prec < 10 and j <= nr_irqs: