perf/core: Disallow uncore-cgroup events

While discussing uncore event scheduling, I noticed we do not in fact
seem to dis-allow making uncore-cgroup events. Such events make no
sense what so ever because the cgroup is a CPU local state where
uncore counts across a number of CPUs.

Disallow them.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vince Weaver <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

1 files changed, 9 insertions, 0 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index aec8dba2bea4..022a34b66e60 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10535,6 +10535,15 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 		goto err_ns;
 	}
 
+	/*
+	 * Disallow uncore-cgroup events, they don't make sense as the cgroup will
+	 * be different on other CPUs in the uncore mask.
+	 */
+	if (pmu->task_ctx_nr == perf_invalid_context && cgroup_fd != -1) {
+		err = -EINVAL;
+		goto err_pmu;
+	}
+
 	if (event->attr.aux_output &&
 	    !(pmu->capabilities & PERF_PMU_CAP_AUX_OUTPUT)) {
 		err = -EOPNOTSUPP;