[PATCH AUTOSEL 5.4 326/330] perf parse-events: Use strcmp() to compare the PMU name

Sasha Levin
2020-09-18T02:08:26Z

From: Jin Yao <yao.jin@linux.intel.com>

[ Upstream commit 8510895bafdbf7c4dd24c22946d925691135c2b2 ]

A big uncore event group is split into multiple small groups which only
include the uncore events from the same PMU. This has been supported in
the commit 3cdc5c2cb924a ("perf parse-events: Handle uncore event
aliases in small groups properly").

If the event's PMU name starts to repeat, it must be a new event.
That can be used to distinguish the leader from other members.
But now it only compares the pointer of pmu_name
(leader->pmu_name == evsel->pmu_name).

If we use "perf stat -M LLC_MISSES.PCIE_WRITE -a" on cascadelakex,
the event list is:

evsel->name evsel->pmu_name
---------------------------------------------------------------
unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_4 (as leader)
unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_2
unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_0
unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_5
unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_3
unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_1
unc_iio_data_req_of_cpu.mem_write.part1 uncore_iio_4
......

For the event "unc_iio_data_req_of_cpu.mem_write.part1" with
"uncore_iio_4", it should be the event from PMU "uncore_iio_4".
It's not a new leader for this PMU.

But if we use "(leader->pmu_name == evsel->pmu_name)", the check
would be failed and the event is stored to leaders[] as a new
PMU leader.

So this patch uses strcmp to compare the PMU name between events.

Fixes: d4953f7ef1a2 ("perf parse-events: Fix 3 use after frees found with clang ASAN")
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200430003618.17002-1-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/util/parse-events.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index f16748cfcb262..3fb9d53666d15 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1507,12 +1507,11 @@ parse_events__set_leader_for_uncore_aliase(char *name, struct list_head *list,
* event. That can be used to distinguish the leader from
* other members, even they have the same event name.
*/
- if ((leader != evsel) && (leader->pmu_name == evsel->pmu_name)) {
+ if ((leader != evsel) &&
+ !strcmp(leader->pmu_name, evsel->pmu_name)) {
is_leader = false;
continue;
}
- /* The name is always alias name */
- WARN_ON(strcmp(leader->name, evsel->name));

/* Store the leader event for each PMU */
leaders[nr_pmu++] = (uintptr_t) evsel;
--
2.25.1