[PATCH 18/29] perf script python: Add trace_context extension module to sys.modules

[Arnaldo Carvalho de Melo <acme@kernel.org>]

From: Tony Jones <tonyj@suse.de>

In Python3, the result of PyModule_Create (called from
scripts/python/Perf-Trace-Util/Context.c) is not automatically added to
sys.modules.  See: https://bugs.python.org/issue4592

Below is the observed behavior without the fix:

  # ldd /usr/bin/perf | grep -i python
	libpython3.6m.so.1.0 => /usr/lib64/libpython3.6m.so.1.0 (0x00007f8e1dfb2000)

  # perf record /bin/false
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.015 MB perf.data (17 samples) ]

  # perf script -g python | cat
  generated Python script: perf-script.py

  # perf script -s ./perf-script.py
  Traceback (most recent call last):
    File "./perf-script.py", line 18, in <module>
      from perf_trace_context import *
  ModuleNotFoundError: No module named 'perf_trace_context'
  Error running python script ./perf-script.py
  #

Committer notes:

To build with python3 use:

  $ make -C tools/perf PYTHON=python3

Signed-off-by: Tony Jones <tonyj@suse.de>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jaroslav Škarvada <jskarvad@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Seeteena Thoufeek <s1seetee@linux.vnet.ibm.com>
Fixes: 66dfdff03d19 ("perf tools: Add Python 3 support")
Link: http://lkml.kernel.org/r/20190124005229.16146-2-tonyj@suse.de
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/scripting-engines/trace-event-python.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
index 87ef16a1b17e..40300d8e80a7 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -1494,6 +1494,7 @@ static void _free_command_line(wchar_t **command_line, int num)
 static int python_start_script(const char *script, int argc, const char **argv)
 {
 	struct tables *tables = &tables_global;
+	PyMODINIT_FUNC (*initfunc)(void);
 #if PY_MAJOR_VERSION < 3
 	const char **command_line;
 #else
@@ -1504,24 +1505,25 @@ static int python_start_script(const char *script, int argc, const char **argv)
 	FILE *fp;
 
 #if PY_MAJOR_VERSION < 3
+	initfunc = initperf_trace_context;
 	command_line = malloc((argc + 1) * sizeof(const char *));
 	command_line[0] = script;
 	for (i = 1; i < argc + 1; i++)
 		command_line[i] = argv[i - 1];
 #else
+	initfunc = PyInit_perf_trace_context;
 	command_line = malloc((argc + 1) * sizeof(wchar_t *));
 	command_line[0] = Py_DecodeLocale(script, NULL);
 	for (i = 1; i < argc + 1; i++)
 		command_line[i] = Py_DecodeLocale(argv[i - 1], NULL);
 #endif
 
+	PyImport_AppendInittab("perf_trace_context", initfunc);
 	Py_Initialize();
 
 #if PY_MAJOR_VERSION < 3
-	initperf_trace_context();
 	PySys_SetArgv(argc + 1, (char **)command_line);
 #else
-	PyInit_perf_trace_context();
 	PySys_SetArgv(argc + 1, command_line);
 #endif
 
-- 
2.20.1