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    Subject[PATCH 1/4] perf tools: Avoid deadlock when map_groups are broken
    Date
    From: Adrian Hunter <adrian.hunter@intel.com>

    Attempting to clone map groups onto themselves will deadlock.

    It only happens because of other bugs, but the code should protect
    itself anyway.

    Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
    Tested-by: Jiri Olsa <jolsa@kernel.org>
    Link: http://lkml.kernel.org/r/1439994561-27436-2-git-send-email-adrian.hunter@intel.com
    [ Use pr_debug() instead of dump_fprintf() ]
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    ---
    tools/perf/util/thread.c | 6 ++++++
    1 file changed, 6 insertions(+)

    diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
    index 28c4b746baa1..0a9ae8014729 100644
    --- a/tools/perf/util/thread.c
    +++ b/tools/perf/util/thread.c
    @@ -191,6 +191,12 @@ static int thread__clone_map_groups(struct thread *thread,
    if (thread->pid_ == parent->pid_)
    return 0;

    + if (thread->mg == parent->mg) {
    + pr_debug("broken map groups on thread %d/%d parent %d/%d\n",
    + thread->pid_, thread->tid, parent->pid_, parent->tid);
    + return 0;
    + }
    +
    /* But this one is new process, copy maps. */
    for (i = 0; i < MAP__NR_TYPES; ++i)
    if (map_groups__clone(thread->mg, parent->mg, i) < 0)
    --
    2.1.0


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