perf: Pass last sampling period to perf_sample_data_init()

We always need to pass the last sample period to
perf_sample_data_init(), otherwise the event distribution will be
wrong. Thus, modifiyng the function interface with the required period
as argument. So basically a pattern like this:

        perf_sample_data_init(&data, ~0ULL);
        data.period = event->hw.last_period;

will now be like that:

        perf_sample_data_init(&data, ~0ULL, event->hw.last_period);

Avoids unininitialized data.period and simplifies code.

Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-3-git-send-email-robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 1 insertions, 2 deletions

diff --git a/arch/alpha/kernel/perf_event.c b/arch/alpha/kernel/perf_event.c
index 0dae252f7a33..d821b17047e0 100644
--- a/arch/alpha/kernel/perf_event.c
+++ b/arch/alpha/kernel/perf_event.c
@@ -824,7 +824,6 @@ static void alpha_perf_event_irq_handler(unsigned long la_ptr,
 
         idx = la_ptr;
 
-        perf_sample_data_init(&data, 0);
         for (j = 0; j < cpuc->n_events; j++) {
                 if (cpuc->current_idx[j] == idx)
                         break;
@@ -848,7 +847,7 @@ static void alpha_perf_event_irq_handler(unsigned long la_ptr,
 
         hwc = &event->hw;
         alpha_perf_event_update(event, hwc, idx, alpha_pmu->pmc_max_period[idx]+1);
-        data.period = event->hw.last_period;
+        perf_sample_data_init(&data, 0, hwc->last_period);
 
         if (alpha_perf_event_set_period(event, hwc, idx)) {
                 if (perf_event_overflow(event, &data, regs)) {