perfcounters: use hw_event.disable flag

Impact: implement default-off counters

Make sure that counters that are created with counter.hw_event.disabled=1,
get created in disabled state.

They can be enabled via:

        prctl(PR_TASK_PERF_COUNTERS_ENABLE);

Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 16396e9..5431e79 100644 (file)
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1093,6 +1093,9 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event,
        counter->group_leader           = group_leader;
        counter->hw_ops                 = NULL;
 
+       if (hw_event->disabled)
+               counter->state = PERF_COUNTER_STATE_OFF;
+
        hw_ops = NULL;
        if (!hw_event->raw && hw_event->type < 0)
                hw_ops = sw_perf_counter_init(counter);