genirq: Switch to irq_get_nr_irqs()

Use the irq_get_nr_irqs() function instead of the global variable
'nr_irqs'. Cache the result of this function in a local variable in
order not to rely on CSE (common subexpression elimination). Prepare
for changing 'nr_irqs' from an exported global variable into a variable
with file scope.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241015190953.1266194-22-bvanassche@acm.org

diff --git a/include/linux/irqnr.h b/include/linux/irqnr.h
index 7419b807b71b21e5496297c78ec3a130fb387bf2..a33088d27c54b110e17b31e6baad8da86bf11eb4 100644 (file)
--- 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 e0bff21f30e0a997464b48cc2bdfa67196d76009..ec6d8e72d980f604ded2bfa2143420e0e0095920 100644 (file)
--- 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 9081ada81c3d023a531d65e5a35a31f4d4ebbe55..d226282c5b66b728c48677f7631767b54885f1d8 100644 (file)
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -457,11 +457,12 @@ 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)
 {
+       const unsigned int nr_irqs = irq_get_nr_irqs();
        static int prec;
 
        int i = *(loff_t *) v, j;