[PATCH v2 17/32] perf/core,perf/x86/intel/cqm: add pmu::event_terminate

David Carrillo-Cisneros
2016-05-11T23:07:34Z

Allow a PMU to clean an event before the event's torn down in
perf_events begins.

Utilized in CQM to dettach the cgroup from monr before perf
removes it from event.

Reviewed-by: Stephane Eranian <eranian@google.com>
Signed-off-by: David Carrillo-Cisneros <davidcc@google.com>
---
arch/x86/events/intel/cqm.c | 18 +++++++++++++++---
include/linux/perf_event.h | 6 ++++++
kernel/events/core.c | 4 ++++
3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c
index fb62bac..a5bec07 100644
--- a/arch/x86/events/intel/cqm.c
+++ b/arch/x86/events/intel/cqm.c
@@ -2376,7 +2376,7 @@ static inline bool cqm_group_leader(struct perf_event *event)
return !list_empty(&event->hw.cqm_event_groups_entry);
}

-static void intel_cqm_event_destroy(struct perf_event *event)
+static void intel_cqm_event_terminate(struct perf_event *event)
{
struct perf_event *group_other = NULL;
struct monr *monr;
@@ -2423,6 +2423,19 @@ static void intel_cqm_event_destroy(struct perf_event *event)
if (monr__is_root(monr))
goto exit;

+#ifdef CONFIG_CGROUP_PERF
+ /* Handle cgroup event. */
+ if (event->cgrp) {
+ monr->mon_event_group = NULL;
+ if ((event->cgrp->css.flags & CSS_ONLINE) &&
+ !cgrp_to_cqm_info(event->cgrp)->cont_monitoring)
+ __css_stop_monitoring(&monr__get_mon_cgrp(monr)->css);
+
+ goto exit;
+ }
+ WARN_ON_ONCE(!monr_is_event_type(monr));
+#endif
+
/* Transition all pmonrs to (U)state. */
monr_hrchy_acquire_locks(flags, i);

@@ -2463,8 +2476,6 @@ static int intel_cqm_event_init(struct perf_event *event)
INIT_LIST_HEAD(&event->hw.cqm_event_groups_entry);
INIT_LIST_HEAD(&event->hw.cqm_event_group_entry);

- event->destroy = intel_cqm_event_destroy;
-
mutex_lock(&cqm_mutex);

@@ -2580,6 +2591,7 @@ static struct pmu intel_cqm_pmu = {
.attr_groups = intel_cqm_attr_groups,
.task_ctx_nr = perf_sw_context,
.event_init = intel_cqm_event_init,
+ .event_terminate = intel_cqm_event_terminate,
.add = intel_cqm_event_add,
.del = intel_cqm_event_stop,
.start = intel_cqm_event_start,
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 60dbd5d..73c5a22 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -278,6 +278,12 @@ struct pmu {
int (*event_init) (struct perf_event *event);

/*
+ * Terminate the event for this PMU. Optional complement for a
+ * successful event_init. Called before the event fields are tear down.
+ */
+ void (*event_terminate) (struct perf_event *event);
+
+ /*
* Notification that the event was mapped or unmapped. Called
* in the context of the mapping task.
*/
diff --git a/kernel/events/core.c b/kernel/events/core.c
index b249251..c242e80 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3833,6 +3833,8 @@ static void _free_event(struct perf_event *event)
ring_buffer_attach(event, NULL);
mutex_unlock(&event->mmap_mutex);
}
+ if (event->pmu->event_terminate)
+ event->pmu->event_terminate(event);

if (is_cgroup_event(event))
perf_detach_cgroup(event);
@@ -8851,6 +8853,8 @@ err_per_task:
exclusive_event_destroy(event);

err_pmu:
+ if (event->pmu->event_terminate)
+ event->pmu->event_terminate(event);
if (event->destroy)
event->destroy(event);
module_put(pmu->module);
--
2.8.0.rc3.226.g39d4020