From c2c7983c93f5d86962318be7e7298f1bc3feb1a6 Mon Sep 17 00:00:00 2001
From: Pengpeng Hou <pengpeng@iscas.ac.cn>
Date: Fri, 3 Apr 2026 16:55:56 +0800
Subject: genirq/proc: Size interrupt directory names for 10-digit interrupt
 numbers

/proc/irq/<n>/ directory names are built in `char name[10]` buffers
with `sprintf(name, "%u", irq)`.

Ten-digit IRQ numbers already need 11 bytes including the trailing NUL, and
current sparse-IRQ configurations allow interrupt numbers in that range.

Size the temporary name buffer for the current decimal form and switch
to bounded formatting when creating or removing the proc entry.

Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260404101001.1-genirq-proc-pengpeng@iscas.ac.cn
---
 kernel/irq/proc.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

(limited to 'kernel')

diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index b0999a4f1f68..dfa0b0723642 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -10,6 +10,7 @@
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/interrupt.h>
+#include <linux/kernel.h>
 #include <linux/kernel_stat.h>
 #include <linux/mutex.h>
 #include <linux/string.h>
@@ -326,7 +327,7 @@ void register_handler_proc(unsigned int irq, struct irqaction *action)
 
 #undef MAX_NAMELEN
 
-#define MAX_NAMELEN 10
+#define MAX_NAMELEN 11
 
 void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 {
@@ -348,7 +349,7 @@ void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 		return;
 
 	/* create /proc/irq/1234 */
-	sprintf(name, "%u", irq);
+	snprintf(name, MAX_NAMELEN, "%u", irq);
 	desc->dir = proc_mkdir(name, root_irq_dir);
 	if (!desc->dir)
 		return;
@@ -401,7 +402,7 @@ void unregister_irq_proc(unsigned int irq, struct irq_desc *desc)
 #endif
 	remove_proc_entry("spurious", desc->dir);
 
-	sprintf(name, "%u", irq);
+	snprintf(name, MAX_NAMELEN, "%u", irq);
 	remove_proc_entry(name, root_irq_dir);
 }
 
-- 
cgit v1.2.3


From 95c33a64f203be444954a1e1d855a4820c4f0efa Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@kernel.org>
Date: Sun, 17 May 2026 22:01:38 +0200
Subject: genirq/proc: Avoid formatting zero counts in /proc/interrupts

A large portion of interrupt count entries are zero. There is no point in
formatting the zero value as it is way cheeper to just emit a constant
string.

Collect the number of consecutive zero counts and emit them in one go
before a non-zero count and at the end of the line.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260517194931.034728540@kernel.org
---
 include/linux/interrupt.h |  1 +
 kernel/irq/proc.c         | 43 ++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 39 insertions(+), 5 deletions(-)

(limited to 'kernel')

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 6cd26ffb0505..3bf969ad8fe0 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -864,6 +864,7 @@ static inline void init_irq_proc(void)
 struct seq_file;
 int show_interrupts(struct seq_file *p, void *v);
 int arch_show_interrupts(struct seq_file *p, int prec);
+void irq_proc_emit_counts(struct seq_file *p, unsigned int __percpu *cnts);
 
 extern int early_irq_init(void);
 extern int arch_probe_nr_irqs(void);
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index dfa0b0723642..378b523a1b00 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -451,6 +451,43 @@ int __weak arch_show_interrupts(struct seq_file *p, int prec)
 # define ACTUAL_NR_IRQS irq_get_nr_irqs()
 #endif
 
+/* Same as seq_put_decimal_ull_width(p, " ", cnt, 10) */
+#define ZSTR1 "          0"
+#define ZSTR1_LEN	(sizeof(ZSTR1) - 1)
+#define ZSTR16		ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 \
+			ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1
+#define ZSTR256		ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 \
+			ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16
+
+static inline void irq_proc_emit_zero_counts(struct seq_file *p, unsigned int zeros)
+{
+	if (!zeros)
+		return;
+
+	for (unsigned int n = min(zeros, 256); n; zeros -= n, n = min(zeros, 256))
+		seq_write(p, ZSTR256, n * ZSTR1_LEN);
+}
+
+static inline unsigned int irq_proc_emit_count(struct seq_file *p, unsigned int cnt,
+					       unsigned int zeros)
+{
+	if (!cnt)
+		return zeros + 1;
+
+	irq_proc_emit_zero_counts(p, zeros);
+	seq_put_decimal_ull_width(p, " ", cnt, 10);
+	return 0;
+}
+
+void irq_proc_emit_counts(struct seq_file *p, unsigned int __percpu *cnts)
+{
+	unsigned int cpu, zeros = 0;
+
+	for_each_online_cpu(cpu)
+		zeros = irq_proc_emit_count(p, per_cpu(*cnts, cpu), zeros);
+	irq_proc_emit_zero_counts(p, zeros);
+}
+
 int show_interrupts(struct seq_file *p, void *v)
 {
 	const unsigned int nr_irqs = irq_get_nr_irqs();
@@ -486,11 +523,7 @@ int show_interrupts(struct seq_file *p, void *v)
 		return 0;
 
 	seq_printf(p, "%*d:", prec, i);
-	for_each_online_cpu(j) {
-		unsigned int cnt = desc->kstat_irqs ? per_cpu(desc->kstat_irqs->cnt, j) : 0;
-
-		seq_put_decimal_ull_width(p, " ", cnt, 10);
-	}
+	irq_proc_emit_counts(p, &desc->kstat_irqs->cnt);
 	seq_putc(p, ' ');
 
 	guard(raw_spinlock_irq)(&desc->lock);
-- 
cgit v1.2.3


From 0179464391af9a01b911f441d2dda42ea253dfbd Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@kernel.org>
Date: Sun, 17 May 2026 22:01:43 +0200
Subject: genirq/proc: Utilize irq_desc::tot_count to avoid evaluation

Interrupts which are not marked per CPU increment not only the per CPU
statistics, but also the accumulation counter irq_desc::tot_count.

Change the counter to type unsigned long so it does not produce sporadic
zeros due to wrap arounds on 64-bit machines and do a quick check for non
per CPU interrupts. If the counter is zero, then simply emit a full set of
zero strings. That spares the evaluation of the per CPU counters completely
for interrupts with zero events.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
Link: https://patch.msgid.link/20260517194931.115522199@kernel.org
---
 include/linux/irqdesc.h |  6 +++---
 kernel/irq/proc.c       | 11 ++++++++++-
 2 files changed, 13 insertions(+), 4 deletions(-)

(limited to 'kernel')

diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index dae9a9b93665..1058786d76eb 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -52,8 +52,8 @@ struct irq_redirect {
  * @depth:		disable-depth, for nested irq_disable() calls
  * @wake_depth:		enable depth, for multiple irq_set_irq_wake() callers
  * @tot_count:		stats field for non-percpu irqs
- * @irq_count:		stats field to detect stalled irqs
  * @last_unhandled:	aging timer for unhandled count
+ * @irq_count:		stats field to detect stalled irqs
  * @irqs_unhandled:	stats field for spurious unhandled interrupts
  * @threads_handled:	stats field for deferred spurious detection of threaded handlers
  * @threads_handled_last: comparator field for deferred spurious detection of threaded handlers
@@ -87,9 +87,9 @@ struct irq_desc {
 	unsigned int		core_internal_state__do_not_mess_with_it;
 	unsigned int		depth;		/* nested irq disables */
 	unsigned int		wake_depth;	/* nested wake enables */
-	unsigned int		tot_count;
-	unsigned int		irq_count;	/* For detecting broken IRQs */
+	unsigned long		tot_count;
 	unsigned long		last_unhandled;	/* Aging timer for unhandled count */
+	unsigned int		irq_count;	/* For detecting broken IRQs */
 	unsigned int		irqs_unhandled;
 	atomic_t		threads_handled;
 	int			threads_handled_last;
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 378b523a1b00..5a1805b0b8a9 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -523,7 +523,16 @@ int show_interrupts(struct seq_file *p, void *v)
 		return 0;
 
 	seq_printf(p, "%*d:", prec, i);
-	irq_proc_emit_counts(p, &desc->kstat_irqs->cnt);
+
+	/*
+	 * Always output per CPU interrupts. Output device interrupts only when
+	 * desc::tot_count is not zero.
+	 */
+	if (irq_settings_is_per_cpu(desc) || irq_settings_is_per_cpu_devid(desc) ||
+	    data_race(desc->tot_count))
+		irq_proc_emit_counts(p, &desc->kstat_irqs->cnt);
+	else
+		irq_proc_emit_zero_counts(p, num_online_cpus());
 	seq_putc(p, ' ');
 
 	guard(raw_spinlock_irq)(&desc->lock);
-- 
cgit v1.2.3


From b99dc723b12ea587fc8b2e07bd8401433eec58d8 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@kernel.org>
Date: Sun, 17 May 2026 22:02:09 +0200
Subject: genirq: Expose nr_irqs in core code

... 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>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260517194931.522168332@kernel.org
---
 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(-)

(limited to 'kernel')

diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index 9412e57056f5..db359acdf27f 100644
--- 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;
 
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 7173b8b634f2..a7ce1e8165a6 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -140,14 +140,14 @@ static void desc_set_defaults(unsigned int irq, struct irq_desc *desc, int node,
 	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(unsigned int offset)
 	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 int nr)
 {
 	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, unsigned int cnt)
 {
 	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, unsigned int from, unsigned int cnt, int no
 	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)
 {
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 5a1805b0b8a9..d5b812680f5c 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -448,7 +448,7 @@ int __weak arch_show_interrupts(struct seq_file *p, int prec)
 }
 
 #ifndef ACTUAL_NR_IRQS
-# define ACTUAL_NR_IRQS irq_get_nr_irqs()
+# define ACTUAL_NR_IRQS total_nr_irqs
 #endif
 
 /* Same as seq_put_decimal_ull_width(p, " ", cnt, 10) */
@@ -490,7 +490,7 @@ void irq_proc_emit_counts(struct seq_file *p, unsigned int __percpu *cnts)
 
 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;
diff --git a/scripts/gdb/linux/interrupts.py b/scripts/gdb/linux/interrupts.py
index b794e013c360..a4e25d2bf123 100644
--- a/scripts/gdb/linux/interrupts.py
+++ b/scripts/gdb/linux/interrupts.py
@@ -174,7 +174,7 @@ class LxInterruptList(gdb.Command):
         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:
-- 
cgit v1.2.3


From 3ba92f6a28203e30d0b2c7d75b59f48d5ff9fbcc Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@kernel.org>
Date: Sun, 17 May 2026 22:02:14 +0200
Subject: genirq/manage: Make NMI cleanup RT safe

Eventually blocking functions cannot be invoked with interrupts disabled
and a raw spin lock held. Restructure the code so this happens outside of
the descriptor lock held region.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Link: https://patch.msgid.link/20260517194931.601972758@kernel.org
---
 kernel/irq/manage.c | 37 +++++++++++++++++++++----------------
 1 file changed, 21 insertions(+), 16 deletions(-)

(limited to 'kernel')

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 2e8072437826..8863b2d4b8ca 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -2026,24 +2026,30 @@ const void *free_irq(unsigned int irq, void *dev_id)
 }
 EXPORT_SYMBOL(free_irq);
 
-/* This function must be called with desc->lock held */
 static const void *__cleanup_nmi(unsigned int irq, struct irq_desc *desc)
 {
+	struct irqaction *action = NULL;
 	const char *devname = NULL;
 
-	desc->istate &= ~IRQS_NMI;
+	scoped_guard(raw_spinlock_irqsave, &desc->lock) {
+		irq_nmi_teardown(desc);
 
-	if (!WARN_ON(desc->action == NULL)) {
-		irq_pm_remove_action(desc, desc->action);
-		devname = desc->action->name;
-		unregister_handler_proc(irq, desc->action);
+		desc->istate &= ~IRQS_NMI;
 
-		kfree(desc->action);
+		if (!WARN_ON(desc->action == NULL)) {
+			action = desc->action;
+			irq_pm_remove_action(desc, action);
+			devname = action->name;
+		}
 		desc->action = NULL;
+
+		irq_settings_clr_disable_unlazy(desc);
+		irq_shutdown_and_deactivate(desc);
 	}
 
-	irq_settings_clr_disable_unlazy(desc);
-	irq_shutdown_and_deactivate(desc);
+	if (action)
+		unregister_handler_proc(irq, action);
+	kfree(action);
 
 	irq_release_resources(desc);
 
@@ -2067,8 +2073,6 @@ const void *free_nmi(unsigned int irq, void *dev_id)
 	if (WARN_ON(desc->depth == 0))
 		disable_nmi_nosync(irq);
 
-	guard(raw_spinlock_irqsave)(&desc->lock);
-	irq_nmi_teardown(desc);
 	return __cleanup_nmi(irq, desc);
 }
 
@@ -2318,13 +2322,14 @@ int request_nmi(unsigned int irq, irq_handler_t handler,
 		/* Setup NMI state */
 		desc->istate |= IRQS_NMI;
 		retval = irq_nmi_setup(desc);
-		if (retval) {
-			__cleanup_nmi(irq, desc);
-			return -EINVAL;
-		}
-		return 0;
 	}
 
+	if (retval) {
+		__cleanup_nmi(irq, desc);
+		return -EINVAL;
+	}
+	return 0;
+
 err_irq_setup:
 	irq_chip_pm_put(&desc->irq_data);
 err_out:
-- 
cgit v1.2.3


From 4892e5e71ec9c942293cea7fd26e0c76179211ed Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@kernel.org>
Date: Sun, 17 May 2026 22:02:19 +0200
Subject: genirq: Cache the condition for /proc/interrupts exposure

show_interrupts() evaluates a boatload of conditions to establish whether
it should expose an interrupt in /proc/interrupts or not.

That can be simplified by caching the condition in an internal status flag,
which is updated when one of the relevant inputs changes.

The irq_desc::kstat_irq check is dropped because visible interrupt
descriptors always have a valid pointer.

As a result the number of instructions and branches for reading
/proc/interrupts is reduced significantly.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
Link: https://patch.msgid.link/20260517194931.680943749@kernel.org
---
 include/linux/irq.h    |  1 +
 kernel/irq/chip.c      |  2 ++
 kernel/irq/internals.h |  2 ++
 kernel/irq/manage.c    |  8 +++++++-
 kernel/irq/proc.c      | 15 +++++++++++----
 kernel/irq/settings.h  | 13 +++++++++++++
 6 files changed, 36 insertions(+), 5 deletions(-)

(limited to 'kernel')

diff --git a/include/linux/irq.h b/include/linux/irq.h
index efa514ee562f..f485369b1b4f 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -103,6 +103,7 @@ enum {
 	IRQ_DISABLE_UNLAZY	= (1 << 19),
 	IRQ_HIDDEN		= (1 << 20),
 	IRQ_NO_DEBUG		= (1 << 21),
+	IRQ_RESERVED		= (1 << 22),
 };
 
 #define IRQF_MODIFY_MASK	\
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 6c9b1dc4e7d4..2d283d1390dc 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -1007,6 +1007,7 @@ __irq_do_set_handler(struct irq_desc *desc, irq_flow_handler_t handle,
 		WARN_ON(irq_chip_pm_get(irq_desc_get_irq_data(desc)));
 		irq_activate_and_startup(desc, IRQ_RESEND);
 	}
+	irq_proc_update_valid(desc);
 }
 
 void __irq_set_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
@@ -1067,6 +1068,7 @@ void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
 			trigger = tmp;
 
 		irqd_set(&desc->irq_data, trigger);
+		irq_proc_update_valid(desc);
 	}
 }
 EXPORT_SYMBOL_GPL(irq_modify_status);
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index db359acdf27f..e5f3d310a825 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -123,6 +123,7 @@ extern void register_irq_proc(unsigned int irq, struct irq_desc *desc);
 extern void unregister_irq_proc(unsigned int irq, struct irq_desc *desc);
 extern void register_handler_proc(unsigned int irq, struct irqaction *action);
 extern void unregister_handler_proc(unsigned int irq, struct irqaction *action);
+void irq_proc_update_valid(struct irq_desc *desc);
 #else
 static inline void register_irq_proc(unsigned int irq, struct irq_desc *desc) { }
 static inline void unregister_irq_proc(unsigned int irq, struct irq_desc *desc) { }
@@ -130,6 +131,7 @@ static inline void register_handler_proc(unsigned int irq,
 					 struct irqaction *action) { }
 static inline void unregister_handler_proc(unsigned int irq,
 					   struct irqaction *action) { }
+static inline void irq_proc_update_valid(struct irq_desc *desc) { }
 #endif
 
 extern bool irq_can_set_affinity_usr(unsigned int irq);
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 8863b2d4b8ca..7eb07e3bdb4c 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1802,6 +1802,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 		__enable_irq(desc);
 	}
 
+	irq_proc_update_valid(desc);
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
 	chip_bus_sync_unlock(desc);
 	mutex_unlock(&desc->request_mutex);
@@ -1906,6 +1907,7 @@ static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id)
 		desc->affinity_hint = NULL;
 #endif
 
+	irq_proc_update_valid(desc);
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
 	/*
 	 * Drop bus_lock here so the changes which were done in the chip
@@ -2047,6 +2049,8 @@ static const void *__cleanup_nmi(unsigned int irq, struct irq_desc *desc)
 		irq_shutdown_and_deactivate(desc);
 	}
 
+	irq_proc_update_valid(desc);
+
 	if (action)
 		unregister_handler_proc(irq, action);
 	kfree(action);
@@ -2433,8 +2437,10 @@ static struct irqaction *__free_percpu_irq(unsigned int irq, void __percpu *dev_
 		*action_ptr = action->next;
 
 		/* Demote from NMI if we killed the last action */
-		if (!desc->action)
+		if (!desc->action) {
 			desc->istate &= ~IRQS_NMI;
+			irq_proc_update_valid(desc);
+		}
 	}
 
 	unregister_handler_proc(irq, action);
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index d5b812680f5c..cc9c7c907dd2 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -440,6 +440,16 @@ void init_irq_proc(void)
 		register_irq_proc(irq, desc);
 }
 
+void irq_proc_update_valid(struct irq_desc *desc)
+{
+	u32 set = _IRQ_PROC_VALID;
+
+	if (irq_settings_is_hidden(desc) || irq_desc_is_chained(desc) || !desc->action)
+		set = 0;
+
+	irq_settings_update_proc_valid(desc, set);
+}
+
 #ifdef CONFIG_GENERIC_IRQ_SHOW
 
 int __weak arch_show_interrupts(struct seq_file *p, int prec)
@@ -516,10 +526,7 @@ int show_interrupts(struct seq_file *p, void *v)
 
 	guard(rcu)();
 	desc = irq_to_desc(i);
-	if (!desc || irq_settings_is_hidden(desc))
-		return 0;
-
-	if (!desc->action || irq_desc_is_chained(desc) || !desc->kstat_irqs)
+	if (!desc || !irq_settings_proc_valid(desc))
 		return 0;
 
 	seq_printf(p, "%*d:", prec, i);
diff --git a/kernel/irq/settings.h b/kernel/irq/settings.h
index 00b3bd127692..0a0c027a5d34 100644
--- a/kernel/irq/settings.h
+++ b/kernel/irq/settings.h
@@ -18,6 +18,7 @@ enum {
 	_IRQ_DISABLE_UNLAZY	= IRQ_DISABLE_UNLAZY,
 	_IRQ_HIDDEN		= IRQ_HIDDEN,
 	_IRQ_NO_DEBUG		= IRQ_NO_DEBUG,
+	_IRQ_PROC_VALID		= IRQ_RESERVED,
 	_IRQF_MODIFY_MASK	= IRQF_MODIFY_MASK,
 };
 
@@ -34,6 +35,7 @@ enum {
 #define IRQ_DISABLE_UNLAZY	GOT_YOU_MORON
 #define IRQ_HIDDEN		GOT_YOU_MORON
 #define IRQ_NO_DEBUG		GOT_YOU_MORON
+#define IRQ_RESERVED		GOT_YOU_MORON
 #undef IRQF_MODIFY_MASK
 #define IRQF_MODIFY_MASK	GOT_YOU_MORON
 
@@ -180,3 +182,14 @@ static inline bool irq_settings_no_debug(struct irq_desc *desc)
 {
 	return desc->status_use_accessors & _IRQ_NO_DEBUG;
 }
+
+static inline bool irq_settings_proc_valid(struct irq_desc *desc)
+{
+	return desc->status_use_accessors & _IRQ_PROC_VALID;
+}
+
+static inline void irq_settings_update_proc_valid(struct irq_desc *desc, u32 set)
+{
+	desc->status_use_accessors &= ~_IRQ_PROC_VALID;
+	desc->status_use_accessors |= (set & _IRQ_PROC_VALID);
+}
-- 
cgit v1.2.3


From 2d62735f1d4a2832af367c9e3de04bfb280a945c Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@kernel.org>
Date: Sun, 17 May 2026 22:02:24 +0200
Subject: genirq: Calculate precision only when required

Calculating the precision of the interrupt number column on every initial
show_interrupt() invocation is a pointless exercise as the underlying
maximum number of interrupts rarely changes.

Calculate it only when that number is modified and let show_interrupts()
use the cached value.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
Link: https://patch.msgid.link/20260517194931.760664517@kernel.org
---
 kernel/irq/internals.h |  6 ++++++
 kernel/irq/irqdesc.c   | 10 ++++++----
 kernel/irq/proc.c      | 33 +++++++++++++++++++++++----------
 3 files changed, 35 insertions(+), 14 deletions(-)

(limited to 'kernel')

diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index e5f3d310a825..be702dd64422 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -134,6 +134,12 @@ static inline void unregister_handler_proc(unsigned int irq,
 static inline void irq_proc_update_valid(struct irq_desc *desc) { }
 #endif
 
+#if defined(CONFIG_PROC_FS) && defined(CONFIG_GENERIC_IRQ_SHOW)
+void irq_proc_calc_prec(void);
+#else
+static inline void irq_proc_calc_prec(void) { }
+#endif
+
 extern bool irq_can_set_affinity_usr(unsigned int irq);
 
 extern int irq_do_set_affinity(struct irq_data *data,
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index a7ce1e8165a6..90595eefb477 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -157,13 +157,12 @@ EXPORT_SYMBOL_GPL(irq_get_nr_irqs);
  *
  * Return: @nr.
  */
-unsigned int irq_set_nr_irqs(unsigned int nr)
+unsigned int __init irq_set_nr_irqs(unsigned int nr)
 {
 	total_nr_irqs = nr;
-
+	irq_proc_calc_prec();
 	return nr;
 }
-EXPORT_SYMBOL_GPL(irq_set_nr_irqs);
 
 static DEFINE_MUTEX(sparse_irq_lock);
 static struct maple_tree sparse_irqs = MTREE_INIT_EXT(sparse_irqs,
@@ -544,6 +543,7 @@ static bool irq_expand_nr_irqs(unsigned int nr)
 	if (nr > MAX_SPARSE_IRQS)
 		return false;
 	total_nr_irqs = nr;
+	irq_proc_calc_prec();
 	return true;
 }
 
@@ -572,6 +572,7 @@ int __init early_irq_init(void)
 		desc = alloc_desc(i, node, 0, NULL, NULL);
 		irq_insert_desc(i, desc);
 	}
+	irq_proc_calc_prec();
 	return arch_early_irq_init();
 }
 
@@ -592,7 +593,7 @@ int __init early_irq_init(void)
 
 	init_irq_default_affinity();
 
-	printk(KERN_INFO "NR_IRQS: %d\n", NR_IRQS);
+	pr_info("NR_IRQS: %d\n", NR_IRQS);
 
 	count = ARRAY_SIZE(irq_desc);
 
@@ -602,6 +603,7 @@ int __init early_irq_init(void)
 			goto __free_desc_res;
 	}
 
+	irq_proc_calc_prec();
 	return arch_early_irq_init();
 
 __free_desc_res:
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index cc9c7c907dd2..c635fb62c783 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -457,10 +457,25 @@ int __weak arch_show_interrupts(struct seq_file *p, int prec)
 	return 0;
 }
 
+static struct irq_proc_constraints {
+	unsigned int	num_prec;
+} irq_proc_constraints __read_mostly = {
+	.num_prec	= 3,
+};
+
 #ifndef ACTUAL_NR_IRQS
 # define ACTUAL_NR_IRQS total_nr_irqs
 #endif
 
+void irq_proc_calc_prec(void)
+{
+	unsigned int prec, n;
+
+	for (prec = 3, n = 1000; prec < 10 && n <= total_nr_irqs; ++prec)
+		n *= 10;
+	WRITE_ONCE(irq_proc_constraints.num_prec, prec);
+}
+
 /* Same as seq_put_decimal_ull_width(p, " ", cnt, 10) */
 #define ZSTR1 "          0"
 #define ZSTR1_LEN	(sizeof(ZSTR1) - 1)
@@ -500,9 +515,7 @@ void irq_proc_emit_counts(struct seq_file *p, unsigned int __percpu *cnts)
 
 int show_interrupts(struct seq_file *p, void *v)
 {
-	const unsigned int nr_irqs = total_nr_irqs;
-	static int prec;
-
+	unsigned int prec = READ_ONCE(irq_proc_constraints.num_prec);
 	int i = *(loff_t *) v, j;
 	struct irqaction *action;
 	struct irq_desc *desc;
@@ -515,9 +528,6 @@ int show_interrupts(struct seq_file *p, void *v)
 
 	/* print header and calculate the width of the first column */
 	if (i == 0) {
-		for (prec = 3, j = 1000; prec < 10 && j <= nr_irqs; ++prec)
-			j *= 10;
-
 		seq_printf(p, "%*s", prec + 8, "");
 		for_each_online_cpu(j)
 			seq_printf(p, "CPU%-8d", j);
@@ -553,13 +563,16 @@ int show_interrupts(struct seq_file *p, void *v)
 	} else {
 		seq_printf(p, "%8s", "None");
 	}
+
+	seq_putc(p, ' ');
 	if (desc->irq_data.domain)
-		seq_printf(p, " %*lu", prec, desc->irq_data.hwirq);
+		seq_put_decimal_ull_width(p, "", desc->irq_data.hwirq, prec);
 	else
 		seq_printf(p, " %*s", prec, "");
-#ifdef CONFIG_GENERIC_IRQ_SHOW_LEVEL
-	seq_printf(p, " %-8s", irqd_is_level_type(&desc->irq_data) ? "Level" : "Edge");
-#endif
+
+	if (IS_ENABLED(CONFIG_GENERIC_IRQ_SHOW_LEVEL))
+		seq_printf(p, " %-8s", irqd_is_level_type(&desc->irq_data) ? "Level" : "Edge");
+
 	if (desc->name)
 		seq_printf(p, "-%-8s", desc->name);
 
-- 
cgit v1.2.3


From 34594da7650d3ea67f96c0f4034ff6b2453f67c3 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@kernel.org>
Date: Sun, 17 May 2026 22:02:29 +0200
Subject: genirq/proc: Increase default interrupt number precision to four

Quite some architectures have four character wide acronyms for architecture
specific interrupts like IPI, NMI, etc.

The default precision of printing the Linux device interrupt numbers is
three, which causes quite some code to play games with adding or omitting
space after the acronym and the colon in order to keep the per CPU numbers
properly aligned.

Increase the default number precision to four in the core code and get rid
of the space games all over the place. At the same time align all
architecture specific descriptor texts left so that they show up in the
same column as the interrupt chip names, which makes the output more
uniform accross architectures. Fix up the GDB script to this new scheme as
well.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260517194931.839482411@kernel.org
---
 arch/alpha/kernel/irq.c         |  8 ++++----
 arch/arm/kernel/smp.c           |  3 +--
 arch/arm64/kernel/smp.c         |  5 ++---
 arch/loongarch/kernel/smp.c     |  2 +-
 arch/riscv/kernel/smp.c         |  3 +--
 arch/sh/kernel/irq.c            |  2 +-
 arch/sparc/kernel/irq_32.c      | 12 ++++++------
 arch/sparc/kernel/irq_64.c      |  4 ++--
 arch/um/kernel/irq.c            |  4 ++--
 arch/xtensa/kernel/irq.c        |  2 +-
 kernel/irq/proc.c               |  4 ++--
 scripts/gdb/linux/interrupts.py | 16 ++++++----------
 12 files changed, 29 insertions(+), 36 deletions(-)

(limited to 'kernel')

diff --git a/arch/alpha/kernel/irq.c b/arch/alpha/kernel/irq.c
index c67047c5d830..4a6a8b1d5a8b 100644
--- a/arch/alpha/kernel/irq.c
+++ b/arch/alpha/kernel/irq.c
@@ -72,16 +72,16 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 	int j;
 
 #ifdef CONFIG_SMP
-	seq_puts(p, "IPI: ");
+	seq_puts(p, " IPI: ");
 	for_each_online_cpu(j)
 		seq_printf(p, "%10lu ", cpu_data[j].ipi_count);
 	seq_putc(p, '\n');
 #endif
-	seq_puts(p, "PMI: ");
+	seq_puts(p, " PMI: ");
 	for_each_online_cpu(j)
 		seq_printf(p, "%10lu ", per_cpu(irq_pmi_count, j));
-	seq_puts(p, "          Performance Monitoring\n");
-	seq_printf(p, "ERR: %10lu\n", irq_err_count);
+	seq_puts(p, " Performance Monitoring\n");
+	seq_printf(p, " ERR: %10lu\n", irq_err_count);
 	return 0;
 }
 
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 4e8e89a26ca3..b5fb4697bc3f 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -551,8 +551,7 @@ void show_ipi_list(struct seq_file *p, int prec)
 		if (!ipi_desc[i])
 			continue;
 
-		seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
-			   prec >= 4 ? " " : "");
+		seq_printf(p, "%*s%u:", prec - 1, "IPI", i);
 
 		for_each_online_cpu(cpu)
 			seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 1aa324104afb..1d0e0e6a5b92 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -833,11 +833,10 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 	unsigned int cpu, i;
 
 	for (i = 0; i < MAX_IPI; i++) {
-		seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
-			   prec >= 4 ? " " : "");
+		seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 		for_each_online_cpu(cpu)
 			seq_printf(p, "%10u ", irq_desc_kstat_cpu(get_ipi_desc(cpu, i), cpu));
-		seq_printf(p, "      %s\n", ipi_types[i]);
+		seq_printf(p, " %s\n", ipi_types[i]);
 	}
 
 	seq_printf(p, "%*s: %10lu\n", prec, "Err", irq_err_count);
diff --git a/arch/loongarch/kernel/smp.c b/arch/loongarch/kernel/smp.c
index 64a048f1b880..50922610758b 100644
--- a/arch/loongarch/kernel/smp.c
+++ b/arch/loongarch/kernel/smp.c
@@ -88,7 +88,7 @@ void show_ipi_list(struct seq_file *p, int prec)
 	unsigned int cpu, i;
 
 	for (i = 0; i < NR_IPI; i++) {
-		seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i, prec >= 4 ? " " : "");
+		seq_printf(p, "%*s%u:", prec - 1, "IPI", i);
 		for_each_online_cpu(cpu)
 			seq_put_decimal_ull_width(p, " ", per_cpu(irq_stat, cpu).ipi_irqs[i], 10);
 		seq_printf(p, " LoongArch  %d  %s\n", i + 1, ipi_types[i]);
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index 5ed5095320e6..fa66f9c97d74 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -226,8 +226,7 @@ void show_ipi_stats(struct seq_file *p, int prec)
 	unsigned int cpu, i;
 
 	for (i = 0; i < IPI_MAX; i++) {
-		seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
-			   prec >= 4 ? " " : "");
+		seq_printf(p, "%*s%u:", prec - 1, "IPI", i);
 		for_each_online_cpu(cpu)
 			seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
 		seq_printf(p, " %s\n", ipi_names[i]);
diff --git a/arch/sh/kernel/irq.c b/arch/sh/kernel/irq.c
index 9022d8af9d68..03c39b5da50f 100644
--- a/arch/sh/kernel/irq.c
+++ b/arch/sh/kernel/irq.c
@@ -46,7 +46,7 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 	seq_printf(p, "%*s:", prec, "NMI");
 	for_each_online_cpu(j)
 		seq_put_decimal_ull_width(p, " ", per_cpu(irq_stat.__nmi_count, j), 10);
-	seq_printf(p, "  Non-maskable interrupts\n");
+	seq_printf(p, " Non-maskable interrupts\n");
 
 	seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));
 
diff --git a/arch/sparc/kernel/irq_32.c b/arch/sparc/kernel/irq_32.c
index 5210991429d5..22db727652ba 100644
--- a/arch/sparc/kernel/irq_32.c
+++ b/arch/sparc/kernel/irq_32.c
@@ -199,19 +199,19 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 	int j;
 
 #ifdef CONFIG_SMP
-	seq_printf(p, "RES:");
+	seq_printf(p, "%*s:", prec, "RES");
 	for_each_online_cpu(j)
 		seq_put_decimal_ull_width(p, " ", cpu_data(j).irq_resched_count, 10);
-	seq_printf(p, "     IPI rescheduling interrupts\n");
-	seq_printf(p, "CAL:");
+	seq_printf(p, " IPI rescheduling interrupts\n");
+	seq_printf(p, "%*s:", prec, "CAL");
 	for_each_online_cpu(j)
 		seq_put_decimal_ull_width(p, " ", cpu_data(j).irq_call_count, 10);
-	seq_printf(p, "     IPI function call interrupts\n");
+	seq_printf(p, " IPI function call interrupts\n");
 #endif
-	seq_printf(p, "NMI:");
+	seq_printf(p, "%*s:", prec, "NMI");
 	for_each_online_cpu(j)
 		seq_put_decimal_ull_width(p, " ", cpu_data(j).counter, 10);
-	seq_printf(p, "     Non-maskable interrupts\n");
+	seq_printf(p, " Non-maskable interrupts\n");
 	return 0;
 }
 
diff --git a/arch/sparc/kernel/irq_64.c b/arch/sparc/kernel/irq_64.c
index c5466a9fd560..3f55c69d5f3b 100644
--- a/arch/sparc/kernel/irq_64.c
+++ b/arch/sparc/kernel/irq_64.c
@@ -303,10 +303,10 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 {
 	int j;
 
-	seq_printf(p, "NMI:");
+	seq_printf(p, "%*s:", prec, "NMI");
 	for_each_online_cpu(j)
 		seq_put_decimal_ull_width(p, " ", cpu_data(j).__nmi_count, 10);
-	seq_printf(p, "     Non-maskable interrupts\n");
+	seq_printf(p, " Non-maskable interrupts\n");
 	return 0;
 }
 
diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c
index 5929d498b65f..ddfd6e9bd8c7 100644
--- a/arch/um/kernel/irq.c
+++ b/arch/um/kernel/irq.c
@@ -716,12 +716,12 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 	seq_printf(p, "%*s: ", prec, "RES");
 	for_each_online_cpu(cpu)
 		seq_printf(p, "%10u ", irq_stats(cpu)->irq_resched_count);
-	seq_puts(p, "  Rescheduling interrupts\n");
+	seq_puts(p, " Rescheduling interrupts\n");
 
 	seq_printf(p, "%*s: ", prec, "CAL");
 	for_each_online_cpu(cpu)
 		seq_printf(p, "%10u ", irq_stats(cpu)->irq_call_count);
-	seq_puts(p, "  Function call interrupts\n");
+	seq_puts(p, " Function call interrupts\n");
 #endif
 
 	return 0;
diff --git a/arch/xtensa/kernel/irq.c b/arch/xtensa/kernel/irq.c
index b1e410f6b5ab..6f01f530868b 100644
--- a/arch/xtensa/kernel/irq.c
+++ b/arch/xtensa/kernel/irq.c
@@ -59,7 +59,7 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 	seq_printf(p, "%*s:", prec, "NMI");
 	for_each_online_cpu(cpu)
 		seq_printf(p, " %10lu", per_cpu(nmi_count, cpu));
-	seq_puts(p, "   Non-maskable interrupts\n");
+	seq_puts(p, " Non-maskable interrupts\n");
 #endif
 	return 0;
 }
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index c635fb62c783..1cb47a8eab49 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -460,7 +460,7 @@ int __weak arch_show_interrupts(struct seq_file *p, int prec)
 static struct irq_proc_constraints {
 	unsigned int	num_prec;
 } irq_proc_constraints __read_mostly = {
-	.num_prec	= 3,
+	.num_prec	= 4,
 };
 
 #ifndef ACTUAL_NR_IRQS
@@ -471,7 +471,7 @@ void irq_proc_calc_prec(void)
 {
 	unsigned int prec, n;
 
-	for (prec = 3, n = 1000; prec < 10 && n <= total_nr_irqs; ++prec)
+	for (prec = 4, n = 10000; prec < 10 && n <= total_nr_irqs; ++prec)
 		n *= 10;
 	WRITE_ONCE(irq_proc_constraints.num_prec, prec);
 }
diff --git a/scripts/gdb/linux/interrupts.py b/scripts/gdb/linux/interrupts.py
index a4e25d2bf123..e96734348f86 100644
--- a/scripts/gdb/linux/interrupts.py
+++ b/scripts/gdb/linux/interrupts.py
@@ -131,23 +131,19 @@ def arm_common_show_interrupts(prec):
     if nr_ipi is None or ipi_desc is None or ipi_types is None:
         return text
 
-    if prec >= 4:
-        sep = " "
-    else:
-        sep = ""
-
     for ipi in range(nr_ipi):
-        text += "%*s%u:%s" % (prec - 1, "IPI", ipi, sep)
+        text += "%*s%u: " % (prec - 1, "IPI", ipi)
         desc = ipi_desc[ipi].cast(irq_desc_type.get_type().pointer())
         if desc == 0:
             continue
         for cpu in cpus.each_online_cpu():
-            text += "%10u" % (cpus.per_cpu(desc['kstat_irqs'], cpu)['cnt'])
-        text += "      %s" % (ipi_types[ipi].string())
+            text += "%10u " % (cpus.per_cpu(desc['kstat_irqs'], cpu)['cnt'])
+        text += "%s" % (ipi_types[ipi].string())
         text += "\n"
     return text
 
 def aarch64_show_interrupts(prec):
+    # Does not work for ARM64 as "ipi_desc" is not available there
     text = arm_common_show_interrupts(prec)
     text += "%*s: %10lu\n" % (prec, "ERR", gdb.parse_and_eval("irq_err_count"))
     return text
@@ -175,8 +171,8 @@ class LxInterruptList(gdb.Command):
 
     def invoke(self, arg, from_tty):
         nr_irqs = gdb.parse_and_eval("total_nr_irqs")
-        prec = 3
-        j = 1000
+        prec = 4
+        j = 10000
         while prec < 10 and j <= nr_irqs:
             prec += 1
             j *= 10
-- 
cgit v1.2.3


From 1d9c4745bfb6773712751f5068c23ebad9cd30a0 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@kernel.org>
Date: Sun, 17 May 2026 22:02:34 +0200
Subject: genirq: Add rcuref count to struct irq_desc

Prepare for a smarter iterator for /proc/interrupts so that the next
interrupt descriptor can be cached after lookup.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Link: https://patch.msgid.link/20260517194931.917415190@kernel.org
---
 include/linux/irqdesc.h |  2 ++
 kernel/irq/internals.h  | 17 ++++++++++++++++-
 kernel/irq/irqdesc.c    | 21 +++++++++++++--------
 3 files changed, 31 insertions(+), 9 deletions(-)

(limited to 'kernel')

diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 1058786d76eb..8080db17c1b1 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -70,6 +70,7 @@ struct irq_redirect {
  *			IRQF_NO_SUSPEND set
  * @force_resume_depth:	number of irqactions on a irq descriptor with
  *			IRQF_FORCE_RESUME set
+ * @refcnt:		Reference count mainly for /proc/interrupts
  * @rcu:		rcu head for delayed free
  * @kobj:		kobject used to represent this struct in sysfs
  * @request_mutex:	mutex to protect request/free before locking desc->lock
@@ -119,6 +120,7 @@ struct irq_desc {
 	struct dentry		*debugfs_file;
 	const char		*dev_name;
 #endif
+	rcuref_t		refcnt;
 #ifdef CONFIG_SPARSE_IRQ
 	struct rcu_head		rcu;
 	struct kobject		kobj;
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index be702dd64422..bacbf4020242 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -9,6 +9,7 @@
 #include <linux/irqdesc.h>
 #include <linux/kernel_stat.h>
 #include <linux/pm_runtime.h>
+#include <linux/rcuref.h>
 #include <linux/sched/clock.h>
 
 #ifdef CONFIG_SPARSE_IRQ
@@ -101,9 +102,23 @@ extern void unmask_irq(struct irq_desc *desc);
 extern void unmask_threaded_irq(struct irq_desc *desc);
 
 #ifdef CONFIG_SPARSE_IRQ
-static inline void irq_mark_irq(unsigned int irq) { }
+static __always_inline void irq_mark_irq(unsigned int irq) { }
+void irq_desc_free_rcu(struct irq_desc *desc);
+
+static __always_inline bool irq_desc_get_ref(struct irq_desc *desc)
+{
+	return rcuref_get(&desc->refcnt);
+}
+
+static __always_inline void irq_desc_put_ref(struct irq_desc *desc)
+{
+	if (rcuref_put(&desc->refcnt))
+		irq_desc_free_rcu(desc);
+}
 #else
 extern void irq_mark_irq(unsigned int irq);
+static __always_inline bool irq_desc_get_ref(struct irq_desc *desc) { return true; }
+static __always_inline void irq_desc_put_ref(struct irq_desc *desc) { }
 #endif
 
 irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc);
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 90595eefb477..23f21763bfed 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -137,6 +137,7 @@ static void desc_set_defaults(unsigned int irq, struct irq_desc *desc, int node,
 	desc->tot_count = 0;
 	desc->name = NULL;
 	desc->owner = owner;
+	rcuref_init(&desc->refcnt, 1);
 	desc_smp_init(desc, node, affinity);
 }
 
@@ -465,6 +466,17 @@ static void delayed_free_desc(struct rcu_head *rhp)
 	kobject_put(&desc->kobj);
 }
 
+void irq_desc_free_rcu(struct irq_desc *desc)
+{
+	/*
+	 * We free the descriptor, masks and stat fields via RCU. That
+	 * allows demultiplex interrupts to do rcu based management of
+	 * the child interrupts.
+	 * This also allows us to use rcu in kstat_irqs_usr().
+	 */
+	call_rcu(&desc->rcu, delayed_free_desc);
+}
+
 static void free_desc(unsigned int irq)
 {
 	struct irq_desc *desc = irq_to_desc(irq);
@@ -483,14 +495,7 @@ static void free_desc(unsigned int irq)
 	 */
 	irq_sysfs_del(desc);
 	delete_irq_desc(irq);
-
-	/*
-	 * We free the descriptor, masks and stat fields via RCU. That
-	 * allows demultiplex interrupts to do rcu based management of
-	 * the child interrupts.
-	 * This also allows us to use rcu in kstat_irqs_usr().
-	 */
-	call_rcu(&desc->rcu, delayed_free_desc);
+	irq_desc_put_ref(desc);
 }
 
 static int alloc_descs(unsigned int start, unsigned int cnt, int node,
-- 
cgit v1.2.3


From 7603e0575d8a92318bd4695917fce7ec2c5825a1 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@kernel.org>
Date: Sun, 17 May 2026 22:02:39 +0200
Subject: genirq: Expose irq_find_desc_at_or_after() in core code

... in preparation for a smarter iterator for /proc/interrupts.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Link: https://patch.msgid.link/20260517194932.005787611@kernel.org
---
 kernel/irq/internals.h |  2 ++
 kernel/irq/irqdesc.c   | 15 ++++++++-------
 2 files changed, 10 insertions(+), 7 deletions(-)

(limited to 'kernel')

diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index bacbf4020242..37eec0337867 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -155,6 +155,8 @@ void irq_proc_calc_prec(void);
 static inline void irq_proc_calc_prec(void) { }
 #endif
 
+struct irq_desc *irq_find_desc_at_or_after(unsigned int offset);
+
 extern bool irq_can_set_affinity_usr(unsigned int irq);
 
 extern int irq_do_set_affinity(struct irq_data *data,
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 23f21763bfed..80ef4e27dcf4 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -181,15 +181,12 @@ static int irq_find_free_area(unsigned int from, unsigned int cnt)
 	return mas.index;
 }
 
-static unsigned int irq_find_at_or_after(unsigned int offset)
+struct irq_desc *irq_find_desc_at_or_after(unsigned int offset)
 {
 	unsigned long index = offset;
-	struct irq_desc *desc;
-
-	guard(rcu)();
-	desc = mt_find(&sparse_irqs, &index, total_nr_irqs);
 
-	return desc ? irq_desc_get_irq(desc) : total_nr_irqs;
+	lockdep_assert_in_rcu_read_lock();
+	return mt_find(&sparse_irqs, &index, total_nr_irqs);
 }
 
 static void irq_insert_desc(unsigned int irq, struct irq_desc *desc)
@@ -934,7 +931,11 @@ EXPORT_SYMBOL_GPL(__irq_alloc_descs);
  */
 unsigned int irq_get_next_irq(unsigned int offset)
 {
-	return irq_find_at_or_after(offset);
+	struct irq_desc *desc;
+
+	guard(rcu)();
+	desc = irq_find_desc_at_or_after(offset);
+	return desc ? irq_desc_get_irq(desc) : total_nr_irqs;
 }
 
 struct irq_desc *__irq_get_desc_lock(unsigned int irq, unsigned long *flags, bool bus,
-- 
cgit v1.2.3


From 61b51a167c524b65a59b1342e70c2008d514a796 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@kernel.org>
Date: Sun, 17 May 2026 22:02:44 +0200
Subject: genirq/proc: Runtime size the chip name

The chip name column in the /proc/interrupt output is 8 characters and
right aligned, which causes visual clutter due to the fixed length and the
alignment. Many interrupt chips, e.g. PCI/MSI[X] have way longer names.

Update the length when a chip is assigned to an interrupt and utilize this
information for the output. Align it left so all chip names start at the
begin of the column.

Update the GDB script as well and disentangle the header maze so it
actually works with all .config combinations.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Link: https://patch.msgid.link/20260517194932.085786035@kernel.org
---
 kernel/irq/chip.c               |  6 ++++--
 kernel/irq/debugfs.h            | 44 +++++++++++++++++++++++++++++++++++++
 kernel/irq/internals.h          | 48 +++--------------------------------------
 kernel/irq/irqdomain.c          |  5 ++++-
 kernel/irq/proc.c               | 33 +++++++++++++++++++++++-----
 kernel/irq/proc.h               | 13 +++++++++++
 scripts/gdb/linux/interrupts.py | 23 +++++++++++++-------
 7 files changed, 111 insertions(+), 61 deletions(-)
 create mode 100644 kernel/irq/debugfs.h
 create mode 100644 kernel/irq/proc.h

(limited to 'kernel')

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 2d283d1390dc..934777925f5c 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -47,9 +47,11 @@ int irq_set_chip(unsigned int irq, const struct irq_chip *chip)
 		scoped_irqdesc->irq_data.chip = (struct irq_chip *)(chip ?: &no_irq_chip);
 		ret = 0;
 	}
-	/* For !CONFIG_SPARSE_IRQ make the irq show up in allocated_irqs. */
-	if (!ret)
+	if (!ret) {
+		/* For !CONFIG_SPARSE_IRQ make the irq show up in allocated_irqs. */
 		irq_mark_irq(irq);
+		irq_proc_update_chip(chip);
+	}
 	return ret;
 }
 EXPORT_SYMBOL(irq_set_chip);
diff --git a/kernel/irq/debugfs.h b/kernel/irq/debugfs.h
new file mode 100644
index 000000000000..8a9360d5fefb
--- /dev/null
+++ b/kernel/irq/debugfs.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _KERNEL_IRQ_DEBUGFS_H
+#define _KERNEL_IRQ_DEBUGFS_H
+
+#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
+#include <linux/debugfs.h>
+
+struct irq_bit_descr {
+	unsigned int	mask;
+	char		*name;
+};
+
+#define BIT_MASK_DESCR(m)	{ .mask = m, .name = #m }
+
+void irq_debug_show_bits(struct seq_file *m, int ind, unsigned int state,
+			 const struct irq_bit_descr *sd, int size);
+
+void irq_add_debugfs_entry(unsigned int irq, struct irq_desc *desc);
+static inline void irq_remove_debugfs_entry(struct irq_desc *desc)
+{
+	debugfs_remove(desc->debugfs_file);
+	kfree(desc->dev_name);
+}
+void irq_debugfs_copy_devname(int irq, struct device *dev);
+# ifdef CONFIG_IRQ_DOMAIN
+void irq_domain_debugfs_init(struct dentry *root);
+# else
+static inline void irq_domain_debugfs_init(struct dentry *root)
+{
+}
+# endif
+#else /* CONFIG_GENERIC_IRQ_DEBUGFS */
+static inline void irq_add_debugfs_entry(unsigned int irq, struct irq_desc *d)
+{
+}
+static inline void irq_remove_debugfs_entry(struct irq_desc *d)
+{
+}
+static inline void irq_debugfs_copy_devname(int irq, struct device *dev)
+{
+}
+#endif /* CONFIG_GENERIC_IRQ_DEBUGFS */
+
+#endif
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index 37eec0337867..f9c099d45a64 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -12,6 +12,9 @@
 #include <linux/rcuref.h>
 #include <linux/sched/clock.h>
 
+#include "debugfs.h"
+#include "proc.h"
+
 #ifdef CONFIG_SPARSE_IRQ
 # define MAX_SPARSE_IRQS	INT_MAX
 #else
@@ -149,12 +152,6 @@ static inline void unregister_handler_proc(unsigned int irq,
 static inline void irq_proc_update_valid(struct irq_desc *desc) { }
 #endif
 
-#if defined(CONFIG_PROC_FS) && defined(CONFIG_GENERIC_IRQ_SHOW)
-void irq_proc_calc_prec(void);
-#else
-static inline void irq_proc_calc_prec(void) { }
-#endif
-
 struct irq_desc *irq_find_desc_at_or_after(unsigned int offset);
 
 extern bool irq_can_set_affinity_usr(unsigned int irq);
@@ -398,42 +395,3 @@ static inline struct irq_data *irqd_get_parent_data(struct irq_data *irqd)
 	return NULL;
 #endif
 }
-
-#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
-#include <linux/debugfs.h>
-
-struct irq_bit_descr {
-	unsigned int	mask;
-	char		*name;
-};
-
-#define BIT_MASK_DESCR(m)	{ .mask = m, .name = #m }
-
-void irq_debug_show_bits(struct seq_file *m, int ind, unsigned int state,
-			 const struct irq_bit_descr *sd, int size);
-
-void irq_add_debugfs_entry(unsigned int irq, struct irq_desc *desc);
-static inline void irq_remove_debugfs_entry(struct irq_desc *desc)
-{
-	debugfs_remove(desc->debugfs_file);
-	kfree(desc->dev_name);
-}
-void irq_debugfs_copy_devname(int irq, struct device *dev);
-# ifdef CONFIG_IRQ_DOMAIN
-void irq_domain_debugfs_init(struct dentry *root);
-# else
-static inline void irq_domain_debugfs_init(struct dentry *root)
-{
-}
-# endif
-#else /* CONFIG_GENERIC_IRQ_DEBUGFS */
-static inline void irq_add_debugfs_entry(unsigned int irq, struct irq_desc *d)
-{
-}
-static inline void irq_remove_debugfs_entry(struct irq_desc *d)
-{
-}
-static inline void irq_debugfs_copy_devname(int irq, struct device *dev)
-{
-}
-#endif /* CONFIG_GENERIC_IRQ_DEBUGFS */
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index cc93abf009e8..f15c9f1223bb 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -20,6 +20,8 @@
 #include <linux/smp.h>
 #include <linux/fs.h>
 
+#include "proc.h"
+
 static LIST_HEAD(irq_domain_list);
 static DEFINE_MUTEX(irq_domain_mutex);
 
@@ -1532,6 +1534,7 @@ int irq_domain_set_hwirq_and_chip(struct irq_domain *domain, unsigned int virq,
 	irq_data->chip = (struct irq_chip *)(chip ? chip : &no_irq_chip);
 	irq_data->chip_data = chip_data;
 
+	irq_proc_update_chip(chip);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(irq_domain_set_hwirq_and_chip);
@@ -2081,7 +2084,7 @@ static void irq_domain_free_one_irq(struct irq_domain *domain, unsigned int virq
 #endif	/* CONFIG_IRQ_DOMAIN_HIERARCHY */
 
 #ifdef CONFIG_GENERIC_IRQ_DEBUGFS
-#include "internals.h"
+#include "debugfs.h"
 
 static struct dentry *domain_dir;
 
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 1cb47a8eab49..9a968007eb2d 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -457,10 +457,14 @@ int __weak arch_show_interrupts(struct seq_file *p, int prec)
 	return 0;
 }
 
+static DEFINE_RAW_SPINLOCK(irq_proc_constraints_lock);
+
 static struct irq_proc_constraints {
 	unsigned int	num_prec;
+	unsigned int	chip_width;
 } irq_proc_constraints __read_mostly = {
 	.num_prec	= 4,
+	.chip_width	= 8,
 };
 
 #ifndef ACTUAL_NR_IRQS
@@ -473,7 +477,23 @@ void irq_proc_calc_prec(void)
 
 	for (prec = 4, n = 10000; prec < 10 && n <= total_nr_irqs; ++prec)
 		n *= 10;
-	WRITE_ONCE(irq_proc_constraints.num_prec, prec);
+
+	guard(raw_spinlock_irqsave)(&irq_proc_constraints_lock);
+	if (prec > irq_proc_constraints.num_prec)
+		WRITE_ONCE(irq_proc_constraints.num_prec, prec);
+}
+
+void irq_proc_update_chip(const struct irq_chip *chip)
+{
+	unsigned int len = chip && chip->name ? strlen(chip->name) : 0;
+
+	if (!len || len <= READ_ONCE(irq_proc_constraints.chip_width))
+		return;
+
+	/* Can be invoked from interrupt disabled contexts */
+	guard(raw_spinlock_irqsave)(&irq_proc_constraints_lock);
+	if (len > irq_proc_constraints.chip_width)
+		WRITE_ONCE(irq_proc_constraints.chip_width, len);
 }
 
 /* Same as seq_put_decimal_ull_width(p, " ", cnt, 10) */
@@ -515,6 +535,7 @@ void irq_proc_emit_counts(struct seq_file *p, unsigned int __percpu *cnts)
 
 int show_interrupts(struct seq_file *p, void *v)
 {
+	unsigned int chip_width = READ_ONCE(irq_proc_constraints.chip_width);
 	unsigned int prec = READ_ONCE(irq_proc_constraints.num_prec);
 	int i = *(loff_t *) v, j;
 	struct irqaction *action;
@@ -550,18 +571,20 @@ int show_interrupts(struct seq_file *p, void *v)
 		irq_proc_emit_counts(p, &desc->kstat_irqs->cnt);
 	else
 		irq_proc_emit_zero_counts(p, num_online_cpus());
-	seq_putc(p, ' ');
+
+	/* Enforce a visual gap */
+	seq_write(p, "  ", 2);
 
 	guard(raw_spinlock_irq)(&desc->lock);
 	if (desc->irq_data.chip) {
 		if (desc->irq_data.chip->irq_print_chip)
 			desc->irq_data.chip->irq_print_chip(&desc->irq_data, p);
 		else if (desc->irq_data.chip->name)
-			seq_printf(p, "%8s", desc->irq_data.chip->name);
+			seq_printf(p, "%-*s", chip_width, desc->irq_data.chip->name);
 		else
-			seq_printf(p, "%8s", "-");
+			seq_printf(p, "%-*s", chip_width, "-");
 	} else {
-		seq_printf(p, "%8s", "None");
+		seq_printf(p, "%-*s", chip_width, "None");
 	}
 
 	seq_putc(p, ' ');
diff --git a/kernel/irq/proc.h b/kernel/irq/proc.h
new file mode 100644
index 000000000000..0631d57fbfb7
--- /dev/null
+++ b/kernel/irq/proc.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _KERNEL_IRQ_PROC_H
+#define _KERNEL_IRQ_PROC_H
+
+#if defined(CONFIG_PROC_FS) && defined(CONFIG_GENERIC_IRQ_SHOW)
+void irq_proc_calc_prec(void);
+void irq_proc_update_chip(const struct irq_chip *chip);
+#else
+static inline void irq_proc_calc_prec(void) { }
+static inline void irq_proc_update_chip(const struct irq_chip *chip) { }
+#endif
+
+#endif
diff --git a/scripts/gdb/linux/interrupts.py b/scripts/gdb/linux/interrupts.py
index e96734348f86..a68ae91b4531 100644
--- a/scripts/gdb/linux/interrupts.py
+++ b/scripts/gdb/linux/interrupts.py
@@ -20,7 +20,7 @@ def irq_desc_is_chained(desc):
 def irqd_is_level(desc):
     return desc['irq_data']['common']['state_use_accessors'] & constants.LX_IRQD_LEVEL
 
-def show_irq_desc(prec, irq):
+def show_irq_desc(prec, chip_width, irq):
     text = ""
 
     desc = mapletree.mtree_load(gdb.parse_and_eval("&sparse_irqs"), irq)
@@ -58,7 +58,7 @@ def show_irq_desc(prec, irq):
         else:
             name = "-"
 
-    text += "  %-8s" % (name)
+    text += "  %-*s" % (chip_width, name)
 
     if desc['irq_data']['domain']:
         text += "  %*lu" % (prec, desc['irq_data']['hwirq'])
@@ -171,11 +171,18 @@ class LxInterruptList(gdb.Command):
 
     def invoke(self, arg, from_tty):
         nr_irqs = gdb.parse_and_eval("total_nr_irqs")
-        prec = 4
-        j = 10000
-        while prec < 10 and j <= nr_irqs:
-            prec += 1
-            j *= 10
+        constr = utils.gdb_eval_or_none('irq_proc_constraints')
+
+        if constr:
+            prec = int(constr['num_prec'])
+            chip_width = int(constr['chip_width'])
+        else:
+            prec = 4
+            j = 10000
+            while prec < 10 and j <= nr_irqs:
+                prec += 1
+                j *= 10
+            chip_width = 8
 
         gdb.write("%*s" % (prec + 8, ""))
         for cpu in cpus.each_online_cpu():
@@ -186,7 +193,7 @@ class LxInterruptList(gdb.Command):
             raise gdb.GdbError("Unable to find the sparse IRQ tree, is CONFIG_SPARSE_IRQ enabled?")
 
         for irq in range(nr_irqs):
-            gdb.write(show_irq_desc(prec, irq))
+            gdb.write(show_irq_desc(prec, chip_width, irq))
         gdb.write(arch_show_interrupts(prec))
 
 
-- 
cgit v1.2.3


From 171cc0d9eed1cad5de7ce6a212efbeda390edb0f Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@kernel.org>
Date: Sun, 17 May 2026 22:02:49 +0200
Subject: genirq/proc: Speed up /proc/interrupts iteration

Reading /proc/interrupts iterates over the interrupt number space one by
one and looks up the descriptors one by one. That's just a waste of time.

When CONFIG_GENERIC_IRQ_SHOW is enabled this can utilize the maple tree and
cache the descriptor pointer efficiently for the sequence file operations.

Implement a CONFIG_GENERIC_IRQ_SHOW specific version in the core code and
leave the fs/proc/ variant for the legacy architectures which ignore generic
code.

This reduces the time wasted for looking up the next record significantly.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Link: https://patch.msgid.link/20260517194932.165280601@kernel.org
---
 fs/proc/Makefile  |   4 +-
 kernel/irq/proc.c | 116 ++++++++++++++++++++++++++++++++++++++++++------------
 2 files changed, 94 insertions(+), 26 deletions(-)

(limited to 'kernel')

diff --git a/fs/proc/Makefile b/fs/proc/Makefile
index 7b4db9c56e6a..8bc615ff84e5 100644
--- a/fs/proc/Makefile
+++ b/fs/proc/Makefile
@@ -16,7 +16,9 @@ proc-y	+= cmdline.o
 proc-y	+= consoles.o
 proc-y	+= cpuinfo.o
 proc-y	+= devices.o
-proc-y	+= interrupts.o
+ifneq ($(CONFIG_GENERIC_IRQ_SHOW),y)
+proc-y += interrupts.o
+endif
 proc-y	+= loadavg.o
 proc-y	+= meminfo.o
 proc-y	+= stat.o
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 9a968007eb2d..1b835725f7b1 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -452,6 +452,8 @@ void irq_proc_update_valid(struct irq_desc *desc)
 
 #ifdef CONFIG_GENERIC_IRQ_SHOW
 
+#define ARCH_PROC_IRQDESC ((void *)0x00001111)
+
 int __weak arch_show_interrupts(struct seq_file *p, int prec)
 {
 	return 0;
@@ -460,6 +462,7 @@ int __weak arch_show_interrupts(struct seq_file *p, int prec)
 static DEFINE_RAW_SPINLOCK(irq_proc_constraints_lock);
 
 static struct irq_proc_constraints {
+	bool		print_header;
 	unsigned int	num_prec;
 	unsigned int	chip_width;
 } irq_proc_constraints __read_mostly = {
@@ -533,34 +536,28 @@ void irq_proc_emit_counts(struct seq_file *p, unsigned int __percpu *cnts)
 	irq_proc_emit_zero_counts(p, zeros);
 }
 
-int show_interrupts(struct seq_file *p, void *v)
+static int irq_seq_show(struct seq_file *p, void *v)
 {
-	unsigned int chip_width = READ_ONCE(irq_proc_constraints.chip_width);
-	unsigned int prec = READ_ONCE(irq_proc_constraints.num_prec);
-	int i = *(loff_t *) v, j;
+	struct irq_proc_constraints *constr = p->private;
+	struct irq_desc *desc = v;
 	struct irqaction *action;
-	struct irq_desc *desc;
 
-	if (i > ACTUAL_NR_IRQS)
-		return 0;
+	/* Print header for the first interrupt? */
+	if (constr->print_header) {
+		unsigned int cpu;
 
-	if (i == ACTUAL_NR_IRQS)
-		return arch_show_interrupts(p, prec);
-
-	/* print header and calculate the width of the first column */
-	if (i == 0) {
-		seq_printf(p, "%*s", prec + 8, "");
-		for_each_online_cpu(j)
-			seq_printf(p, "CPU%-8d", j);
+		seq_printf(p, "%*s", constr->num_prec + 8, "");
+		for_each_online_cpu(cpu)
+			seq_printf(p, "CPU%-8d", cpu);
 		seq_putc(p, '\n');
+		constr->print_header = false;
 	}
 
-	guard(rcu)();
-	desc = irq_to_desc(i);
-	if (!desc || !irq_settings_proc_valid(desc))
-		return 0;
+	if (desc == ARCH_PROC_IRQDESC)
+		return arch_show_interrupts(p, constr->num_prec);
 
-	seq_printf(p, "%*d:", prec, i);
+	seq_put_decimal_ull_width(p, "", irq_desc_get_irq(desc), constr->num_prec);
+	seq_putc(p, ':');
 
 	/*
 	 * Always output per CPU interrupts. Output device interrupts only when
@@ -580,18 +577,18 @@ int show_interrupts(struct seq_file *p, void *v)
 		if (desc->irq_data.chip->irq_print_chip)
 			desc->irq_data.chip->irq_print_chip(&desc->irq_data, p);
 		else if (desc->irq_data.chip->name)
-			seq_printf(p, "%-*s", chip_width, desc->irq_data.chip->name);
+			seq_printf(p, "%-*s", constr->chip_width, desc->irq_data.chip->name);
 		else
-			seq_printf(p, "%-*s", chip_width, "-");
+			seq_printf(p, "%-*s", constr->chip_width, "-");
 	} else {
-		seq_printf(p, "%-*s", chip_width, "None");
+		seq_printf(p, "%-*s", constr->chip_width, "None");
 	}
 
 	seq_putc(p, ' ');
 	if (desc->irq_data.domain)
-		seq_put_decimal_ull_width(p, "", desc->irq_data.hwirq, prec);
+		seq_put_decimal_ull_width(p, "", desc->irq_data.hwirq, constr->num_prec);
 	else
-		seq_printf(p, " %*s", prec, "");
+		seq_printf(p, " %*s", constr->num_prec, "");
 
 	if (IS_ENABLED(CONFIG_GENERIC_IRQ_SHOW_LEVEL))
 		seq_printf(p, " %-8s", irqd_is_level_type(&desc->irq_data) ? "Level" : "Edge");
@@ -609,4 +606,73 @@ int show_interrupts(struct seq_file *p, void *v)
 	seq_putc(p, '\n');
 	return 0;
 }
+
+static void *irq_seq_next_desc(loff_t *pos)
+{
+	if (*pos > total_nr_irqs)
+		return NULL;
+
+	guard(rcu)();
+	for (;;) {
+		struct irq_desc *desc = irq_find_desc_at_or_after((unsigned int) *pos);
+
+		if (desc) {
+			*pos = irq_desc_get_irq(desc);
+			/*
+			 * If valid for output then try to acquire a reference
+			 * count on the descriptor so that it can't be freed
+			 * after dropping RCU read lock on return.
+			 */
+			if (irq_settings_proc_valid(desc) && irq_desc_get_ref(desc))
+				return desc;
+			(*pos)++;
+		} else {
+			*pos = total_nr_irqs;
+			return ARCH_PROC_IRQDESC;
+		}
+	}
+}
+
+static void *irq_seq_start(struct seq_file *f, loff_t *pos)
+{
+	if (!*pos) {
+		struct irq_proc_constraints *constr = f->private;
+
+		constr->num_prec = READ_ONCE(irq_proc_constraints.num_prec);
+		constr->chip_width = READ_ONCE(irq_proc_constraints.chip_width);
+		constr->print_header = true;
+	}
+	return irq_seq_next_desc(pos);
+}
+
+static void *irq_seq_next(struct seq_file *f, void *v, loff_t *pos)
+{
+	if (v && v != ARCH_PROC_IRQDESC)
+		irq_desc_put_ref(v);
+
+	(*pos)++;
+	return irq_seq_next_desc(pos);
+}
+
+static void irq_seq_stop(struct seq_file *f, void *v)
+{
+	if (v && v != ARCH_PROC_IRQDESC)
+		irq_desc_put_ref(v);
+}
+
+static const struct seq_operations irq_seq_ops = {
+	.start = irq_seq_start,
+	.next  = irq_seq_next,
+	.stop  = irq_seq_stop,
+	.show  = irq_seq_show,
+};
+
+static int __init irq_proc_init(void)
+{
+	proc_create_seq_private("interrupts", 0, NULL, &irq_seq_ops,
+				sizeof(irq_proc_constraints), NULL);
+	return 0;
+}
+fs_initcall(irq_proc_init);
+
 #endif
-- 
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