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Subject[tip: perf/urgent] perf/core: Disallow uncore-cgroup events
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@infradead.org>
AuthorDate: Wed, 06 Nov 2019 12:51:04 +01:00
Committer: Ingo Molnar <mingo@kernel.org>
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@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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;
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