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

[David Carrillo-Cisneros]

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 <eran...@google.com>
Signed-off-by: David Carrillo-Cisneros <davi...@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