ARM: Remove custom IRQ stat accounting

Let's switch the arm code to the core accounting, which already
does everything we need.
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm/include/asm/hardirq.h

@@ -6,29 +6,12 @@
 #include <linux/threads.h>
 #include <asm/irq.h>
 
-/* number of IPIS _not_ including IPI_CPU_BACKTRACE */
-#define NR_IPI	7
-
 typedef struct {
 	unsigned int __softirq_pending;
-#ifdef CONFIG_SMP
-	unsigned int ipi_irqs[NR_IPI];
-#endif
 } ____cacheline_aligned irq_cpustat_t;
 
 #include <linux/irq_cpustat.h>	/* Standard mappings for irq_cpustat_t above */
 
-#define __inc_irq_stat(cpu, member)	__IRQ_STAT(cpu, member)++
-#define __get_irq_stat(cpu, member)	__IRQ_STAT(cpu, member)
-
-#ifdef CONFIG_SMP
-u64 smp_irq_stat_cpu(unsigned int cpu);
-#else
-#define smp_irq_stat_cpu(cpu)	0
-#endif
-
-#define arch_irq_stat_cpu	smp_irq_stat_cpu
-
 #define __ARCH_IRQ_EXIT_IRQS_DISABLED	1
 
 #endif /* __ASM_HARDIRQ_H */

arch/arm/kernel/irq.c

@@ -18,7 +18,6 @@
  *  IRQ's are in fact implemented a bit like signal handlers for the kernel.
  *  Naturally it's not a 1:1 relation, but there are similarities.
  */
-#include <linux/kernel_stat.h>
 #include <linux/signal.h>
 #include <linux/ioport.h>
 #include <linux/interrupt.h>

arch/arm/kernel/smp.c

@@ -26,6 +26,7 @@
 #include <linux/completion.h>
 #include <linux/cpufreq.h>
 #include <linux/irq_work.h>
+#include <linux/kernel_stat.h>
 
 #include <linux/atomic.h>
 #include <asm/bugs.h>
@@ -65,6 +66,7 @@ enum ipi_msg_type {
 	IPI_CPU_STOP,
 	IPI_IRQ_WORK,
 	IPI_COMPLETION,
+	NR_IPI,
 	/*
 	 * CPU_BACKTRACE is special and not included in NR_IPI
 	 * or tracable with trace_ipi_*
@@ -529,27 +531,16 @@ void show_ipi_list(struct seq_file *p, int prec)
 	unsigned int cpu, i;
 
 	for (i = 0; i < NR_IPI; i++) {
+		unsigned int irq = irq_desc_get_irq(ipi_desc[i]);
 		seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 
 		for_each_online_cpu(cpu)
-			seq_printf(p, "%10u ",
-				   __get_irq_stat(cpu, ipi_irqs[i]));
+			seq_printf(p, "%10u ", kstat_irqs_cpu(irq, cpu));
 
 		seq_printf(p, " %s\n", ipi_types[i]);
 	}
 }
 
-u64 smp_irq_stat_cpu(unsigned int cpu)
-{
-	u64 sum = 0;
-	int i;
-
-	for (i = 0; i < NR_IPI; i++)
-		sum += __get_irq_stat(cpu, ipi_irqs[i]);
-
-	return sum;
-}
-
 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 {
 	smp_cross_call(mask, IPI_CALL_FUNC);
@@ -630,10 +621,8 @@ static void do_handle_IPI(int ipinr)
 {
 	unsigned int cpu = smp_processor_id();
 
-	if ((unsigned)ipinr < NR_IPI) {
+	if ((unsigned)ipinr < NR_IPI)
 		trace_ipi_entry_rcuidle(ipi_types[ipinr]);
-		__inc_irq_stat(cpu, ipi_irqs[ipinr]);
-	}
 
 	switch (ipinr) {
 	case IPI_WAKEUP: