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From e044a7def7f6aa61d3bb2a75a1ef597a4724441b Mon Sep 17 00:00:00 2001
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From: William Cohen <wcohen@redhat.com>
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Date: Mon, 18 Jun 2018 16:47:00 -0400
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Subject: [PATCH] Initialize the trans structure fields to values unused by
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perf samples
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On newer 4.14 kernel operf was crashing because the kernel commit
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1d953111b648e ("perf/core: Don't report zero PIDs for exiting tasks")
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made perf samples have TID/PID of -1 for exiting processes. OProfile
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used this same value internally to indicate the that field had not
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been initialized. As a result operf would incorrectly attempt to run
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some bookkeeping code due to an invalid match. The initialization of
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the trans tgid field is now changed to a value that is unsed by the
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perf samples to ensure that these invalid matches do not occur.
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Signed-off-by: William Cohen <wcohen@redhat.com>
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---
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libperf_events/operf_utils.cpp | 9 ++++++++-
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1 file changed, 8 insertions(+), 1 deletion(-)
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diff --git a/libperf_events/operf_utils.cpp b/libperf_events/operf_utils.cpp
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index 58c50a6..057692d 100644
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--- a/libperf_events/operf_utils.cpp
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+++ b/libperf_events/operf_utils.cpp
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@@ -73,7 +73,14 @@ static inline void update_trans_last(struct operf_transient * trans)
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static inline void clear_trans(struct operf_transient * trans)
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{
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- trans->tgid = ~0U;
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+ /* ~0U (-1) could be used by the kernel perf samples
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+ * for the TID/PID of exiting processes. To avoid
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+ * confusing the oprofile logic use ~1U as the
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+ * initialization value for tgid field to avoid
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+ * possibly matching the TID/PID values for exiting
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+ * processes.
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+ */
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+ trans->tgid = ~1U;
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trans->cur_procinfo = NULL;
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}
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--
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1.8.3.1
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