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    Subject[tip:perf/core] perf tools: Clear struct machine during machine__init()
    Commit-ID:  93b0ba3c60da89043ce2b9f601cd2b3da408903b
    Gitweb: http://git.kernel.org/tip/93b0ba3c60da89043ce2b9f601cd2b3da408903b
    Author: Wang Nan <wangnan0@huawei.com>
    AuthorDate: Tue, 8 Dec 2015 02:25:44 +0000
    Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
    CommitDate: Fri, 11 Dec 2015 09:32:41 -0300

    perf tools: Clear struct machine during machine__init()

    There are so many test cases use stack allocated 'struct machine'.
    Including:
    test__hists_link
    test__hists_filter
    test__mmap_thread_lookup
    test__thread_mg_share
    test__hists_output
    test__hists_cumulate

    Also, in non-test code (for example, machine__new_host()) there are
    code use 'malloc()' to alloc struct machine.

    These are dangerous operations, cause some tests fail or hung in
    machines__exit(). For example, in

    machines__exit ->
    machine__destroy_kernel_maps ->
    map_groups__remove ->
    maps__remove ->
    pthread_rwlock_wrlock

    a incorrectly initialized lock causes unintended behavior.

    This patch memset(0) that structure in machine__init() to ensure all
    fields in 'struct machine' are initialized to zero.

    Signed-off-by: Wang Nan <wangnan0@huawei.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Zefan Li <lizefan@huawei.com>
    Cc: pi3orama@163.com
    Link: http://lkml.kernel.org/r/1449541544-67621-17-git-send-email-wangnan0@huawei.com
    [ Use memset, see 'man bzero' ]
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    ---
    tools/perf/util/machine.c | 1 +
    1 file changed, 1 insertion(+)

    diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
    index f5882b8..1407d51 100644
    --- a/tools/perf/util/machine.c
    +++ b/tools/perf/util/machine.c
    @@ -25,6 +25,7 @@ static void dsos__init(struct dsos *dsos)

    int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
    {
    + memset(machine, 0, sizeof(*machine));
    map_groups__init(&machine->kmaps, machine);
    RB_CLEAR_NODE(&machine->rb_node);
    dsos__init(&machine->dsos);

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