perf/x86/intel/pt: Move transaction start/stop to PMU start/stop callbacks

As per AUX buffer management requirement, AUX output has to happen between
pmu::start and pmu::stop calls so that perf_event_stop() actually stops it
and therefore perf can free the AUX data after it has called pmu::stop.

This patch moves perf_aux_output_{begin,end} from pt_event_{add,del} to
pt_event_{start,stop}. As a bonus, we get rid of pt_buffer_is_full(),
which is already taken care of by perf_aux_output_begin() anyway.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/1457098969-21595-5-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 6af7cf7..127f58c 100644 (file)
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -905,26 +905,6 @@ static void pt_buffer_free_aux(void *data)
        kfree(buf);
 }
 
-/**
- * pt_buffer_is_full() - check if the buffer is full
- * @buf:       PT buffer.
- * @pt:                Per-cpu pt handle.
- *
- * If the user hasn't read data from the output region that aux_head
- * points to, the buffer is considered full: the user needs to read at
- * least this region and update aux_tail to point past it.
- */
-static bool pt_buffer_is_full(struct pt_buffer *buf, struct pt *pt)
-{
-       if (buf->snapshot)
-               return false;
-
-       if (local_read(&buf->data_size) >= pt->handle.size)
-               return true;
-
-       return false;
-}
-
 /**
  * intel_pt_interrupt() - PT PMI handler
  */
@@ -989,20 +969,33 @@ void intel_pt_interrupt(void)
 
 static void pt_event_start(struct perf_event *event, int mode)
 {
+       struct hw_perf_event *hwc = &event->hw;
        struct pt *pt = this_cpu_ptr(&pt_ctx);
-       struct pt_buffer *buf = perf_get_aux(&pt->handle);
+       struct pt_buffer *buf;
 
-       if (!buf || pt_buffer_is_full(buf, pt)) {
-               event->hw.state = PERF_HES_STOPPED;
-               return;
+       buf = perf_aux_output_begin(&pt->handle, event);
+       if (!buf)
+               goto fail_stop;
+
+       pt_buffer_reset_offsets(buf, pt->handle.head);
+       if (!buf->snapshot) {
+               if (pt_buffer_reset_markers(buf, &pt->handle))
+                       goto fail_end_stop;
        }
 
        ACCESS_ONCE(pt->handle_nmi) = 1;
-       event->hw.state = 0;
+       hwc->state = 0;
 
        pt_config_buffer(buf->cur->table, buf->cur_idx,
                         buf->output_off);
        pt_config(event);
+
+       return;
+
+fail_end_stop:
+       perf_aux_output_end(&pt->handle, 0, true);
+fail_stop:
+       hwc->state = PERF_HES_STOPPED;
 }
 
 static void pt_event_stop(struct perf_event *event, int mode)
@@ -1035,19 +1028,7 @@ static void pt_event_stop(struct perf_event *event, int mode)
                pt_handle_status(pt);
 
                pt_update_head(pt);
-       }
-}
 
-static void pt_event_del(struct perf_event *event, int mode)
-{
-       struct pt *pt = this_cpu_ptr(&pt_ctx);
-       struct pt_buffer *buf;
-
-       pt_event_stop(event, PERF_EF_UPDATE);
-
-       buf = perf_get_aux(&pt->handle);
-
-       if (buf) {
                if (buf->snapshot)
                        pt->handle.head =
                                local_xchg(&buf->data_size,
@@ -1057,9 +1038,13 @@ static void pt_event_del(struct perf_event *event, int mode)
        }
 }
 
+static void pt_event_del(struct perf_event *event, int mode)
+{
+       pt_event_stop(event, PERF_EF_UPDATE);
+}
+
 static int pt_event_add(struct perf_event *event, int mode)
 {
-       struct pt_buffer *buf;
        struct pt *pt = this_cpu_ptr(&pt_ctx);
        struct hw_perf_event *hwc = &event->hw;
        int ret = -EBUSY;
@@ -1067,34 +1052,18 @@ static int pt_event_add(struct perf_event *event, int mode)
        if (pt->handle.event)
                goto fail;
 
-       buf = perf_aux_output_begin(&pt->handle, event);
-       ret = -EINVAL;
-       if (!buf)
-               goto fail_stop;
-
-       pt_buffer_reset_offsets(buf, pt->handle.head);
-       if (!buf->snapshot) {
-               ret = pt_buffer_reset_markers(buf, &pt->handle);
-               if (ret)
-                       goto fail_end_stop;
-       }
-
        if (mode & PERF_EF_START) {
                pt_event_start(event, 0);
-               ret = -EBUSY;
+               ret = -EINVAL;
                if (hwc->state == PERF_HES_STOPPED)
-                       goto fail_end_stop;
+                       goto fail;
        } else {
                hwc->state = PERF_HES_STOPPED;
        }
 
-       return 0;
-
-fail_end_stop:
-       perf_aux_output_end(&pt->handle, 0, true);
-fail_stop:
-       hwc->state = PERF_HES_STOPPED;
+       ret = 0;
 fail:
+
        return ret;
 }