commit db4a835601b7
("perf/core: Set cgroup in CPU contexts for new cgroup events")
fails to verify that event->cgrp is actually the scheduled cgroup
in a CPU before setting cpuctx->cgrp. This patch fixes that.
The bug only impacts the first cgroup that is created in a CPU.
Now that there is a different path for scheduled and unscheduled
cgroups, add a warning to catch when cpuctx->cgrp is still set after
the last cgroup event has been unsheduled.
Reviewed-by: Stephane Eranian <eran...@google.com>
Signed-off-by: David Carrillo-Cisneros <davi...@google.com>
---
kernel/events/core.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 7c0d263..62f70a3 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -902,6 +902,17 @@ list_update_cgroup_event(struct perf_event *event,
* this will always be called from the right CPU.
*/
cpuctx = __get_cpu_context(ctx);
+
+ /* Only set/clear cpuctx->cgrp if current task uses event->cgrp. */
+ if (perf_cgroup_from_task(current, ctx) != event->cgrp) {
+ /*
+ * We are removing the last cpu event in this context.
+ * If that event is not active in this cpu, cpuctx->cgrp
+ * should've been cleared by perf_cgroup_switch.
+ */
+ WARN_ON_ONCE(!add && cpuctx->cgrp);
+ return;
+ }
cpuctx->cgrp = add ? event->cgrp : NULL;
}
--
2.8.0.rc3.226.g39d4020
