genirq: Convert kstat_irqs to a struct

The irq_desc::kstat_irqs member is a per-CPU variable of type int, which is
only capable of counting. A snapshot mechanism for interrupt statistics
will be added soon, which requires an additional variable to store the
snapshot.

To facilitate expansion, convert kstat_irqs here to a struct containing
only the count.

Originally-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Bitao Hu <yaoma@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240411074134.30922-2-yaoma@linux.alibaba.com

arch/mips/dec/setup.c

@@ -756,7 +756,7 @@ void __init arch_init_irq(void)
 				NULL))
 			pr_err("Failed to register fpu interrupt\n");
 		desc_fpu = irq_to_desc(irq_fpu);
-		fpu_kstat_irq = this_cpu_ptr(desc_fpu->kstat_irqs);
+		fpu_kstat_irq = this_cpu_ptr(&desc_fpu->kstat_irqs->cnt);
 	}
 	if (dec_interrupt[DEC_IRQ_CASCADE] >= 0) {
 		if (request_irq(dec_interrupt[DEC_IRQ_CASCADE], no_action,

arch/parisc/kernel/smp.c

@@ -344,7 +344,7 @@ static int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
 		struct irq_desc *desc = irq_to_desc(i);
 
 		if (desc && desc->kstat_irqs)
-			*per_cpu_ptr(desc->kstat_irqs, cpuid) = 0;
+			*per_cpu_ptr(desc->kstat_irqs, cpuid) = (struct irqstat) { };
 	}
 #endif
 

arch/powerpc/kvm/book3s_hv_rm_xics.c

@@ -837,7 +837,7 @@ static inline void this_cpu_inc_rm(unsigned int __percpu *addr)
  */
 static void kvmppc_rm_handle_irq_desc(struct irq_desc *desc)
 {
-	this_cpu_inc_rm(desc->kstat_irqs);
+	this_cpu_inc_rm(&desc->kstat_irqs->cnt);
 	__this_cpu_inc(kstat.irqs_sum);
 }
 

include/linux/irqdesc.h

@@ -17,6 +17,14 @@ struct irq_desc;
 struct irq_domain;
 struct pt_regs;
 
+/**
+ * struct irqstat - interrupt statistics
+ * @cnt:	real-time interrupt count
+ */
+struct irqstat {
+	unsigned int	cnt;
+};
+
 /**
  * struct irq_desc - interrupt descriptor
  * @irq_common_data:	per irq and chip data passed down to chip functions
@@ -55,7 +63,7 @@ struct pt_regs;
 struct irq_desc {
 	struct irq_common_data	irq_common_data;
 	struct irq_data		irq_data;
-	unsigned int __percpu	*kstat_irqs;
+	struct irqstat __percpu	*kstat_irqs;
 	irq_flow_handler_t	handle_irq;
 	struct irqaction	*action;	/* IRQ action list */
 	unsigned int		status_use_accessors;
@@ -119,7 +127,7 @@ extern struct irq_desc irq_desc[NR_IRQS];
 static inline unsigned int irq_desc_kstat_cpu(struct irq_desc *desc,
 					      unsigned int cpu)
 {
-	return desc->kstat_irqs ? *per_cpu_ptr(desc->kstat_irqs, cpu) : 0;
+	return desc->kstat_irqs ? per_cpu(desc->kstat_irqs->cnt, cpu) : 0;
 }
 
 static inline struct irq_desc *irq_data_to_desc(struct irq_data *data)

kernel/irq/internals.h

@@ -258,7 +258,7 @@ static inline void irq_state_set_masked(struct irq_desc *desc)
 
 static inline void __kstat_incr_irqs_this_cpu(struct irq_desc *desc)
 {
-	__this_cpu_inc(*desc->kstat_irqs);
+	__this_cpu_inc(desc->kstat_irqs->cnt);
 	__this_cpu_inc(kstat.irqs_sum);
 }
 

kernel/irq/irqdesc.c

@@ -134,7 +134,7 @@ static void desc_set_defaults(unsigned int irq, struct irq_desc *desc, int node,
 	desc->name = NULL;
 	desc->owner = owner;
 	for_each_possible_cpu(cpu)
-		*per_cpu_ptr(desc->kstat_irqs, cpu) = 0;
+		*per_cpu_ptr(desc->kstat_irqs, cpu) = (struct irqstat) { };
 	desc_smp_init(desc, node, affinity);
 }
 
@@ -186,7 +186,7 @@ static int init_desc(struct irq_desc *desc, int irq, int node,
 		     const struct cpumask *affinity,
 		     struct module *owner)
 {
-	desc->kstat_irqs = alloc_percpu(unsigned int);
+	desc->kstat_irqs = alloc_percpu(struct irqstat);
 	if (!desc->kstat_irqs)
 		return -ENOMEM;
 
@@ -968,8 +968,7 @@ unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
 {
 	struct irq_desc *desc = irq_to_desc(irq);
 
-	return desc && desc->kstat_irqs ?
+	return desc && desc->kstat_irqs ? per_cpu(desc->kstat_irqs->cnt, cpu) : 0;
-			*per_cpu_ptr(desc->kstat_irqs, cpu) : 0;
 }
 
 static bool irq_is_nmi(struct irq_desc *desc)
@@ -991,7 +990,7 @@ static unsigned int kstat_irqs(unsigned int irq)
 		return data_race(desc->tot_count);
 
 	for_each_possible_cpu(cpu)
-		sum += data_race(*per_cpu_ptr(desc->kstat_irqs, cpu));
+		sum += data_race(per_cpu(desc->kstat_irqs->cnt, cpu));
 	return sum;
 }
 

kernel/irq/proc.c

@@ -490,7 +490,7 @@ int show_interrupts(struct seq_file *p, void *v)
 
 	if (desc->kstat_irqs) {
 		for_each_online_cpu(j)
-			any_count |= data_race(*per_cpu_ptr(desc->kstat_irqs, j));
+			any_count |= data_race(per_cpu(desc->kstat_irqs->cnt, j));
 	}
 
 	if ((!desc->action || irq_desc_is_chained(desc)) && !any_count)
@@ -498,8 +498,7 @@ int show_interrupts(struct seq_file *p, void *v)
 
 	seq_printf(p, "%*d: ", prec, i);
 	for_each_online_cpu(j)
-		seq_printf(p, "%10u ", desc->kstat_irqs ?
+		seq_printf(p, "%10u ", desc->kstat_irqs ? per_cpu(desc->kstat_irqs->cnt, j) : 0);
-					*per_cpu_ptr(desc->kstat_irqs, j) : 0);
 
 	raw_spin_lock_irqsave(&desc->lock, flags);
 	if (desc->irq_data.chip) {

scripts/gdb/linux/interrupts.py

@@ -37,7 +37,7 @@ def show_irq_desc(prec, irq):
     any_count = 0
     if desc['kstat_irqs']:
         for cpu in cpus.each_online_cpu():
-            any_count += cpus.per_cpu(desc['kstat_irqs'], cpu)
+            any_count += cpus.per_cpu(desc['kstat_irqs'], cpu)['cnt']
 
     if (desc['action'] == 0 or irq_desc_is_chained(desc)) and any_count == 0:
         return text;
@@ -45,7 +45,7 @@ def show_irq_desc(prec, irq):
     text += "%*d: " % (prec, irq)
     for cpu in cpus.each_online_cpu():
         if desc['kstat_irqs']:
-            count = cpus.per_cpu(desc['kstat_irqs'], cpu)
+            count = cpus.per_cpu(desc['kstat_irqs'], cpu)['cnt']
         else:
             count = 0
         text += "%10u" % (count)
@@ -177,7 +177,7 @@ def arm_common_show_interrupts(prec):
         if desc == 0:
             continue
         for cpu in cpus.each_online_cpu():
-            text += "%10u" % (cpus.per_cpu(desc['kstat_irqs'], cpu))
+            text += "%10u" % (cpus.per_cpu(desc['kstat_irqs'], cpu)['cnt'])
         text += "      %s" % (ipi_types[ipi].string())
         text += "\n"
     return text