ARM : fix /proc/interrupts per online cpu

The loop should look at the online cpus instead of the present cpus in order to hide the offline cpus in procfs like it is done on the other architectures.

---
 arch/arm/kernel/smp.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

index ef5640b..050f826 100644
@@ -444,7 +444,7 @@ void show_ipi_list(struct seq_file *p, int prec)
 	for (i = 0; i < NR_IPI; i++) {
 		seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 
-		for_each_present_cpu(cpu)
+		for_each_online_cpu(cpu)
 			seq_printf(p, "%10u ",
 				   __get_irq_stat(cpu, ipi_irqs[i]));
 

1.7.4.1

And what happens if you're reading /proc/interrupts while a CPU is changing state?

Given that it's just user presentation, whether its online or present makes little odds - and having it as present CPUs makes the output 100% stable with the effects of hotplug.

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IMO, there is no problem to read /proc/interrupts while a CPU is changing its state. In the worst case, we will show an obsolete information to the userspace. The same happens when we do 'ps', we have no guarantee a process still exists when the information is displayed. But I may be wrong and in this case, the other arch have a bug.

The procfs is used as an API from the userspace and AFAICS the other architectures display their arch specific interrupts for the online cpus, not the present cpus.

Other non-arch dependant informations are per online cpus, so while looking at the /proc/interrupts we have column shift for the IPI on ARM.

I don't know if it is worth to fix that but that may be more consistent.

Thanks

-- Daniel

./sparc/kernel/irq_64.c:int arch_show_interrupts(struct seq_file *p, int prec)
./sparc/kernel/irq_64.c-{
./sparc/kernel/irq_64.c- int j;
./sparc/kernel/irq_64.c-
./sparc/kernel/irq_64.c- seq_printf(p, "NMI: ");
./sparc/kernel/irq_64.c- for_each_online_cpu(j)
./sparc/kernel/irq_64.c- seq_printf(p, "%10u ", cpu_data(j).__nmi_count);
./sparc/kernel/irq_64.c- seq_printf(p, " Non-maskable interrupts\n");
./sparc/kernel/irq_64.c- return 0;
./sparc/kernel/irq_64.c-}

- -----------------------------------------------------------------------

./sparc/kernel/irq_32.c:int arch_show_interrupts(struct seq_file *p, int prec)
./sparc/kernel/irq_32.c-{
./sparc/kernel/irq_32.c- int j;
./sparc/kernel/irq_32.c-
./sparc/kernel/irq_32.c-#ifdef CONFIG_SMP
./sparc/kernel/irq_32.c- seq_printf(p, "RES: ");
./sparc/kernel/irq_32.c- for_each_online_cpu(j)
./sparc/kernel/irq_32.c- seq_printf(p, "%10u ",
cpu_data(j).irq_resched_count);
./sparc/kernel/irq_32.c- seq_printf(p, " IPI rescheduling
interrupts\n");
./sparc/kernel/irq_32.c- seq_printf(p, "CAL: ");
./sparc/kernel/irq_32.c- for_each_online_cpu(j)

- -----------------------------------------------------------------------

./powerpc/kernel/irq.c:int arch_show_interrupts(struct seq_file *p, int prec)
./powerpc/kernel/irq.c-{
./powerpc/kernel/irq.c- int j;
./powerpc/kernel/irq.c-
./powerpc/kernel/irq.c-#if defined(CONFIG_PPC32) && defined(CONFIG_TAU_INT)
./powerpc/kernel/irq.c- if (tau_initialized) {
./powerpc/kernel/irq.c- seq_printf(p, "%*s: ", prec, "TAU");
./powerpc/kernel/irq.c- for_each_online_cpu(j)
./powerpc/kernel/irq.c- seq_printf(p, "%10u ", tau_interrupts(j));
./powerpc/kernel/irq.c- seq_puts(p, " PowerPC Thermal
Assist (cpu temp)\n");
./powerpc/kernel/irq.c- }

- ------------------------------------------------------------------------

./x86/kernel/irq.c:int arch_show_interrupts(struct seq_file *p, int prec) ./x86/kernel/irq.c-{
./x86/kernel/irq.c- int j;
./x86/kernel/irq.c-
./x86/kernel/irq.c- seq_printf(p, "%*s: ", prec, "NMI");
./x86/kernel/irq.c- for_each_online_cpu(j)
./x86/kernel/irq.c- seq_printf(p, "%10u ", irq_stats(j)->__nmi_count);
./x86/kernel/irq.c- seq_printf(p, " Non-maskable interrupts\n");
./x86/kernel/irq.c-#ifdef CONFIG_X86_LOCAL_APIC
./x86/kernel/irq.c- seq_printf(p, "%*s: ", prec, "LOC");
./x86/kernel/irq.c- for_each_online_cpu(j)

- ------------------------------------------------------------------------

./mn10300/kernel/irq.c:int arch_show_interrupts(struct seq_file *p, int prec)
./mn10300/kernel/irq.c-{
./mn10300/kernel/irq.c-#ifdef CONFIG_MN10300_WD_TIMER
./mn10300/kernel/irq.c- int j;
./mn10300/kernel/irq.c-
./mn10300/kernel/irq.c- seq_printf(p, "%*s: ", prec, "NMI");
./mn10300/kernel/irq.c- for (j = 0; j < NR_CPUS; j++)
./mn10300/kernel/irq.c- if (cpu_online(j))
./mn10300/kernel/irq.c- seq_printf(p, "%10u ", nmi_count(j));
./mn10300/kernel/irq.c- seq_putc(p, '\n');
./mn10300/kernel/irq.c-#endif

- ------------------------------------------------------------------------

./alpha/kernel/irq.c:int arch_show_interrupts(struct seq_file *p, int prec) ./alpha/kernel/irq.c-{
./alpha/kernel/irq.c- int j;
./alpha/kernel/irq.c-
./alpha/kernel/irq.c-#ifdef CONFIG_SMP
./alpha/kernel/irq.c- seq_puts(p, "IPI: ");
./alpha/kernel/irq.c- for_each_online_cpu(j)
./alpha/kernel/irq.c- seq_printf(p, "%10lu ", cpu_data[j].ipi_count);
./alpha/kernel/irq.c- seq_putc(p, '\n');
./alpha/kernel/irq.c-#endif
./alpha/kernel/irq.c- seq_puts(p, "PMI: ");

- ------------------------------------------------------------------------

./sh/kernel/irq.c:int arch_show_interrupts(struct seq_file *p, int prec) ./sh/kernel/irq.c-{
./sh/kernel/irq.c- int j;
./sh/kernel/irq.c-
./sh/kernel/irq.c- seq_printf(p, "%*s: ", prec, "NMI");
./sh/kernel/irq.c- for_each_online_cpu(j)
./sh/kernel/irq.c- seq_printf(p, "%10u ", irq_stat[j].__nmi_count);
./sh/kernel/irq.c- seq_printf(p, " Non-maskable interrupts\n");
./sh/kernel/irq.c-
./sh/kernel/irq.c- seq_printf(p, "%*s: %10u\n", prec, "ERR",
atomic_read(&irq_err_count));
./sh/kernel/irq.c-

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