x86: Distinguish TLB shootdown interrupts from other functions call interrupts

As TLB shootdown requests to other CPU cores are now using function call
interrupts, TLB shootdowns entry in /proc/interrupts is always shown as 0.

This behavior change was introduced by commit 52aec3308db8 ("x86/tlb:
replace INVALIDATE_TLB_VECTOR by CALL_FUNCTION_VECTOR").

This patch reverts TLB shootdowns entry in /proc/interrupts to count TLB
shootdowns separately from the other function call interrupts.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
Link: http://lkml.kernel.org/r/20120926021128.22212.20440.stgit@hpxw
Acked-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/include/asm/hardirq.h

@@ -18,6 +18,10 @@ typedef struct {
 #ifdef CONFIG_SMP
 	unsigned int irq_resched_count;
 	unsigned int irq_call_count;
+	/*
+	 * irq_tlb_count is double-counted in irq_call_count, so it must be
+	 * subtracted from irq_call_count when displaying irq_call_count
+	 */
 	unsigned int irq_tlb_count;
 #endif
 #ifdef CONFIG_X86_THERMAL_VECTOR

arch/x86/kernel/irq.c

@@ -92,7 +92,8 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 	seq_printf(p, "  Rescheduling interrupts\n");
 	seq_printf(p, "%*s: ", prec, "CAL");
 	for_each_online_cpu(j)
-		seq_printf(p, "%10u ", irq_stats(j)->irq_call_count);
+		seq_printf(p, "%10u ", irq_stats(j)->irq_call_count -
+					irq_stats(j)->irq_tlb_count);
 	seq_printf(p, "  Function call interrupts\n");
 	seq_printf(p, "%*s: ", prec, "TLB");
 	for_each_online_cpu(j)
@@ -147,7 +148,6 @@ u64 arch_irq_stat_cpu(unsigned int cpu)
 #ifdef CONFIG_SMP
 	sum += irq_stats(cpu)->irq_resched_count;
 	sum += irq_stats(cpu)->irq_call_count;
-	sum += irq_stats(cpu)->irq_tlb_count;
 #endif
 #ifdef CONFIG_X86_THERMAL_VECTOR
 	sum += irq_stats(cpu)->irq_thermal_count;

arch/x86/mm/tlb.c

@@ -98,6 +98,8 @@ static void flush_tlb_func(void *info)
 {
 	struct flush_tlb_info *f = info;
 
+	inc_irq_stat(irq_tlb_count);
+
 	if (f->flush_mm != this_cpu_read(cpu_tlbstate.active_mm))
 		return;