[tip: perf/urgent] perf/core: Disallow uncore-cgroup events

[tip-bot2 for Peter Zijlstra]

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     09f4e8f05d85bfc98fe9227e988a7c1b3ec416ec
Gitweb:        https://git.kernel.org/tip/09f4e8f05d85bfc98fe9227e988a7c1b3ec416ec
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Wed, 06 Nov 2019 12:51:04 +01:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Wed, 13 Nov 2019 08:16:39 +01:00

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) <peterz@xxxxxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vince Weaver <vincent.weaver@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 kernel/events/core.c |  9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index aec8dba..022a34b 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;