perf_counter: Rework the perf counter disable/enable

The current disable/enable mechanism is:

	token = hw_perf_save_disable();
	...
	/* do bits */
	...
	hw_perf_restore(token);

This works well, provided that the use nests properly. Except we don't.

x86 NMI/INT throttling has non-nested use of this, breaking things. Therefore
provide a reference counter disable/enable interface, where the first disable
disables the hardware, and the last enable enables the hardware again.

[ Impact: refactor, simplify the PMU disable/enable logic ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 4 deletions

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index d2830f39d46b..9645758c0472 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -763,11 +763,9 @@ static int acpi_idle_bm_check(void)
  */
 static inline void acpi_idle_do_entry(struct acpi_processor_cx *cx)
 {
-        u64 perf_flags;
-
         /* Don't trace irqs off for idle */
         stop_critical_timings();
-        perf_flags = hw_perf_save_disable();
+        perf_disable();
         if (cx->entry_method == ACPI_CSTATE_FFH) {
                 /* Call into architectural FFH based C-state */
                 acpi_processor_ffh_cstate_enter(cx);
@@ -782,7 +780,7 @@ static inline void acpi_idle_do_entry(struct acpi_processor_cx *cx)
                    gets asserted in time to freeze execution properly. */
                 unused = inl(acpi_gbl_FADT.xpm_timer_block.address);
         }
-        hw_perf_restore(perf_flags);
+        perf_enable();
         start_critical_timings();
 }