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    Subject[PATCH 4.19 203/245] perf parse-events: Use strcmp() to compare the PMU name
    Date
    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(-)

    --- a/tools/perf/util/parse-events.c
    +++ b/tools/perf/util/parse-events.c
    @@ -1421,12 +1421,11 @@ parse_events__set_leader_for_uncore_alia
    * 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;

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