On 9/30/24 11:15 AM, Bart Van Assche wrote:
> Use the number_of_interrupts() function instead of the global variable
> 'nr_irqs'. This patch prepares for changing 'nr_irqs' from an exported
> global variable into a variable with file scope.
(replying to my own email)
Although no code should loop over all interrupts in the hot path, if
nobody objects, I will replace this patch with the patch below. The
patch below does not rely on CSE (common subexpression eliminiation) to
reduce the number of irq_get_nr_irqs() calls. The patch below should
support code that uses 'break' or 'continue' inside for_each_irq* loops.
Thanks,
Bart.
Subject: [PATCH] genirq: Switch to irq_get_nr_irqs()
Use the irq_get_nr_irqs() function instead of the global variable
'nr_irqs'. This patch prepares for changing 'nr_irqs' from an exported
global variable into a variable with file scope.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
include/linux/irqnr.h | 33 +++++++++++++++++++--------------
kernel/irq/irqdomain.c | 2 +-
kernel/irq/proc.c | 5 +++--
3 files changed, 23 insertions(+), 17 deletions(-)
diff --git a/include/linux/irqnr.h b/include/linux/irqnr.h
index 7419b807b71b..a33088d27c54 100644
--- a/include/linux/irqnr.h
+++ b/include/linux/irqnr.h
@@ -11,26 +11,31 @@ unsigned int irq_set_nr_irqs(unsigned int nr);
extern struct irq_desc *irq_to_desc(unsigned int irq);
unsigned int irq_get_next_irq(unsigned int offset);
-# define for_each_irq_desc(irq, desc) \
- for (irq = 0, desc = irq_to_desc(irq); irq < nr_irqs; \
- irq++, desc = irq_to_desc(irq)) \
- if (!desc) \
- ; \
- else
-
+#define for_each_irq_desc(irq, desc) \
+ for (unsigned int __nr_irqs__ = irq_get_nr_irqs(); __nr_irqs__; \
+ __nr_irqs__ = 0) \
+ for (irq = 0, desc = irq_to_desc(irq); irq < __nr_irqs__; \
+ irq++, desc = irq_to_desc(irq)) \
+ if (!desc) \
+ ; \
+ else
# define for_each_irq_desc_reverse(irq, desc) \
- for (irq = nr_irqs - 1, desc = irq_to_desc(irq); irq >= 0; \
- irq--, desc = irq_to_desc(irq)) \
+ for (irq = irq_get_nr_irqs() - 1, desc = irq_to_desc(irq); \
+ irq >= 0; irq--, desc = irq_to_desc(irq)) \
if (!desc) \
; \
else
-# define for_each_active_irq(irq) \
- for (irq = irq_get_next_irq(0); irq < nr_irqs; \
- irq = irq_get_next_irq(irq + 1))
+#define for_each_active_irq(irq) \
+ for (unsigned int __nr_irqs__ = irq_get_nr_irqs(); __nr_irqs__; \
+ __nr_irqs__ = 0) \
+ for (irq = irq_get_next_irq(0); irq < __nr_irqs__; \
+ irq = irq_get_next_irq(irq + 1))
-#define for_each_irq_nr(irq) \
- for (irq = 0; irq < nr_irqs; irq++)
+#define for_each_irq_nr(irq) \
+ for (unsigned int __nr_irqs__ = irq_get_nr_irqs(); __nr_irqs__; \
+ __nr_irqs__ = 0) \
+ for (irq = 0; irq < __nr_irqs__; irq++)
#endif
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index e0bff21f30e0..ec6d8e72d980 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -1225,7 +1225,7 @@ int irq_domain_alloc_descs(int virq, unsigned int
cnt, irq_hw_number_t hwirq,
virq = __irq_alloc_descs(virq, virq, cnt, node, THIS_MODULE,
affinity);
} else {
- hint = hwirq % nr_irqs;
+ hint = hwirq % irq_get_nr_irqs();
if (hint == 0)
hint++;
virq = __irq_alloc_descs(-1, hint, cnt, node, THIS_MODULE,
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 9081ada81c3d..36ffff4eb352 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -457,7 +457,7 @@ int __weak arch_show_interrupts(struct seq_file *p,
int prec)
}
#ifndef ACTUAL_NR_IRQS
-# define ACTUAL_NR_IRQS nr_irqs
+# define ACTUAL_NR_IRQS irq_get_nr_irqs()
#endif
int show_interrupts(struct seq_file *p, void *v)
@@ -477,7 +477,8 @@ 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)
+ for (prec = 3, j = 1000;
+ prec < 10 && j <= irq_get_nr_irqs(); ++prec)
j *= 10;
seq_printf(p, "%*s", prec + 8, "");