perf_counter: fix hrtimer sampling

Impact: fix deadlock with perfstat

Fix for the perfstat fubar..

We cannot unconditionally call hrtimer_cancel() without ever having done
hrtimer_init() on the thing.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Orig-LKML-Reference: <1236959027.22447.149.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 8d6ecfa..d6cc222 100644 (file)
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1571,9 +1571,9 @@ static int cpu_clock_perf_counter_enable(struct perf_counter *counter)
        int cpu = raw_smp_processor_id();
 
        atomic64_set(&hwc->prev_count, cpu_clock(cpu));
+       hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+       hwc->hrtimer.function = perf_swcounter_hrtimer;
        if (hwc->irq_period) {
-               hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
-               hwc->hrtimer.function = perf_swcounter_hrtimer;
                __hrtimer_start_range_ns(&hwc->hrtimer,
                                ns_to_ktime(hwc->irq_period), 0,
                                HRTIMER_MODE_REL, 0);
@@ -1635,9 +1635,9 @@ static int task_clock_perf_counter_enable(struct perf_counter *counter)
        struct hw_perf_counter *hwc = &counter->hw;
 
        atomic64_set(&hwc->prev_count, task_clock_perf_counter_val(counter, 0));
+       hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+       hwc->hrtimer.function = perf_swcounter_hrtimer;
        if (hwc->irq_period) {
-               hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
-               hwc->hrtimer.function = perf_swcounter_hrtimer;
                __hrtimer_start_range_ns(&hwc->hrtimer,
                                ns_to_ktime(hwc->irq_period), 0,
                                HRTIMER_MODE_REL, 0);