From d3392e4850532c02e53e3c3ff1cc27df7e51c941 Mon Sep 17 00:00:00 2001
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From: Francis Deslauriers <francis.deslauriers@efficios.com>
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Date: Tue, 7 Sep 2021 17:10:31 -0400
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Subject: [PATCH 1/2] Fix: Tests: race condition in test_event_tracker
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Background
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==========
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The `test_event_tracker` file contains test cases when the event
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generating app in executed in two distinct steps. Those two steps are
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preparation and execution.
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1. the preparation is the launching the app in the background, and
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2. the execution is actually generating the event that should or
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should not be traced depending on the test case.
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This is useful to test the tracker feature since we want to ensure that
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already running apps are notified properly when changing their tracking
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status.
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Issue
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=====
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The `test_event_vpid_track_untrack` test case suffers from a race
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condition that is easy to reproduce on Yocto.
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The issue is that sometimes events are end up the trace when none is
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expected.
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This is due to the absence of synchronization point at the launch of the
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app which leads to the app being scheduled in-between the track-untrack
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calls leading to events being recorded to the trace.
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It's easy to reproduce this issue on my machine by adding a `sleep 5`
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between the track and untrack calls and setting the `NR_USEC_WAIT`
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variable to 1.
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Fix
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===
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Using the testapp `--sync-before-last-event-touch` flag to make the app
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create a file when all but the last event are executed. We then have the
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app wait until we create a file (`--sync-before-last-event`) to generate
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that last event. This way, we are sure no event will be generated when
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running the track and untrack commands.
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Notes
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=====
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- This issue affects other test cases in this file.
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- This commit fixes a typo in the test header.
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- This commit adds `diag` calls to help tracking to what test the output
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relates to when reading the log.
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Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
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Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
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Change-Id: Ia2b68128dc9a805526f9748f31ec2c2d95566f31
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Upstream-Status: Backport
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Signed-off-by: Alexander Kanavin <alex.kanavin@gmail.com>
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---
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.../tools/tracker/test_event_tracker | 56 ++++++++++++++-----
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1 file changed, 42 insertions(+), 14 deletions(-)
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diff --git a/tests/regression/tools/tracker/test_event_tracker b/tests/regression/tools/tracker/test_event_tracker
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index feb3787..cc0f698 100755
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--- a/tests/regression/tools/tracker/test_event_tracker
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+++ b/tests/regression/tools/tracker/test_event_tracker
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@@ -5,7 +5,7 @@
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#
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# SPDX-License-Identifier: GPL-2.0-only
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-TEST_DESC="LTTng - Event traker test"
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+TEST_DESC="LTTng - Event tracker test"
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CURDIR=$(dirname "$0")/
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TESTDIR="$CURDIR/../../.."
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@@ -15,7 +15,7 @@ TESTAPP_KERNEL_NAME="gen-kernel-test-events"
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TESTAPP_BIN="$TESTAPP_PATH/$TESTAPP_NAME/$TESTAPP_NAME"
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TESTAPP_KERNEL_BIN="$TESTAPP_PATH/$TESTAPP_KERNEL_NAME/$TESTAPP_KERNEL_NAME"
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SESSION_NAME="tracker"
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-NR_ITER=100
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+NR_ITER=1
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NUM_GLOBAL_TESTS=2
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NUM_UST_TESTS=283
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NUM_KERNEL_TESTS=462
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@@ -30,27 +30,41 @@ SCRIPT_GROUPNAME="$(id -gn)"
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CHILD_PID=-1
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WAIT_PATH=
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-AFTER_FIRST_PATH=
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-BEFORE_LAST_PATH=
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+TOUCH_BEFORE_LAST_PATH=
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+SYNC_BEFORE_LAST_PATH=
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source $TESTDIR/utils/utils.sh
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+# Launch the testapp and execute it up until right before the last event. It is
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+# useful to do it in two seperate steps in order to test tracking and
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+# untracking on an active app.
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function prepare_ust_app
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{
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- AFTER_FIRST_PATH=$(mktemp --tmpdir -u tmp.${FUNCNAME[0]}_sync_after_first.XXXXXX)
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- BEFORE_LAST_PATH=$(mktemp --tmpdir -u tmp.${FUNCNAME[0]}_sync_before_last.XXXXXX)
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+ TOUCH_BEFORE_LAST_PATH=$(mktemp --tmpdir -u tmp.${FUNCNAME[0]}_touch_before_last.XXXXXX)
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+ SYNC_BEFORE_LAST_PATH=$(mktemp --tmpdir -u tmp.${FUNCNAME[0]}_sync_before_last.XXXXXX)
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+
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+ $TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT \
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+ --sync-before-last-event-touch "$TOUCH_BEFORE_LAST_PATH" \
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+ --sync-before-last-event "$SYNC_BEFORE_LAST_PATH" &
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- $TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT -a "$AFTER_FIRST_PATH" -b "$BEFORE_LAST_PATH" &
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CHILD_PID=$!
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+
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+ # Wait for the app to execute all the way to right before the last
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+ # event.
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+ while [ ! -f "${TOUCH_BEFORE_LAST_PATH}" ]; do
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+ sleep 0.5
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+ done
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}
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+# Generate the last event.
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function trace_ust_app
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{
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- touch "$BEFORE_LAST_PATH"
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- wait
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+ # Ask the test app to generate the last event.
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+ touch "$SYNC_BEFORE_LAST_PATH"
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+ wait "$CHILD_PID"
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ok $? "Traced application stopped."
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- rm "$BEFORE_LAST_PATH"
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- rm "$AFTER_FIRST_PATH"
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+ rm "$SYNC_BEFORE_LAST_PATH"
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+ rm "$TOUCH_BEFORE_LAST_PATH"
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}
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function prepare_kernel_app
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@@ -64,7 +78,7 @@ function prepare_kernel_app
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function trace_kernel_app
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{
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touch "$WAIT_PATH"
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- wait
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+ wait "$CHILD_PID"
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ok $? "Traced application stopped."
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rm "$WAIT_PATH"
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}
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@@ -78,6 +92,8 @@ function test_event_tracker()
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local tracker="$4"
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local channel=''
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+ diag "${FUNCNAME[0]} $*"
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+
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trace_path=$(mktemp --tmpdir -d tmp.${FUNCNAME[0]}_trace_path.XXXXXX)
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create_lttng_session_ok $SESSION_NAME "$trace_path"
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@@ -117,6 +133,8 @@ function test_event_vpid_tracker()
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local wildcard="$3"
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local channel=''
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+ diag "${FUNCNAME[0]} $*"
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+
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trace_path=$(mktemp --tmpdir -d tmp.${FUNCNAME[0]}_trace_path.XXXXXX)
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create_lttng_session_ok $SESSION_NAME "$trace_path"
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@@ -160,6 +178,8 @@ function test_event_pid_tracker()
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local wildcard="$3"
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local channel=''
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+ diag "${FUNCNAME[0]} $*"
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+
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trace_path=$(mktemp --tmpdir -d tmp.${FUNCNAME[0]}_trace_path.XXXXXX)
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create_lttng_session_ok $SESSION_NAME "$trace_path"
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@@ -203,6 +223,8 @@ function test_event_tracker_fail()
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local wildcard="$2"
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local tracker="$3"
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+ diag "${FUNCNAME[0]} $*"
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+
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trace_path=$(mktemp --tmpdir -d tmp.${FUNCNAME[0]}_trace_path.XXXXXX)
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create_lttng_session_ok $SESSION_NAME "$trace_path"
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@@ -222,6 +244,8 @@ function test_event_track_untrack()
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local tracker="$4"
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local channel=''
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+ diag "${FUNCNAME[0]} $*"
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+
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trace_path=$(mktemp --tmpdir -d tmp.${FUNCNAME[0]}_trace_path.XXXXXX)
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create_lttng_session_ok $SESSION_NAME "$trace_path"
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@@ -262,6 +286,8 @@ function test_event_vpid_track_untrack()
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local wildcard="$3"
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local channel=''
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+ diag "${FUNCNAME[0]} $*"
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+
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trace_path=$(mktemp --tmpdir -d tmp.${FUNCNAME[0]}_trace_path.XXXXXX)
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create_lttng_session_ok $SESSION_NAME "$trace_path"
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@@ -302,6 +328,8 @@ function test_event_pid_track_untrack()
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local wildcard="$3"
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local channel=''
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+ diag "${FUNCNAME[0]} $*"
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+
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trace_path=$(mktemp --tmpdir -d tmp.${FUNCNAME[0]}_trace_path.XXXXXX)
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create_lttng_session_ok $SESSION_NAME "$trace_path"
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@@ -336,9 +364,9 @@ function test_event_pid_track_untrack()
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function test_event_ust_vpid_untrack_snapshot()
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{
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- local trace_path=$(mktemp --tmpdir -d tmp.${FUNCNAME[0]}_trace_path.XXXXXX)
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+ diag "${FUNCNAME[0]} $*"
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- diag "Test_event_ust_vpid_untrack_snapshot"
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+ local trace_path=$(mktemp --tmpdir -d tmp.${FUNCNAME[0]}_trace_path.XXXXXX)
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create_lttng_session_ok $SESSION_NAME "$trace_path" "--snapshot"
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--
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2.20.1
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