[PATCH AUTOSEL 5.0 214/262] perf script python: Add trace_context extension module to sys.modules

Sasha Levin
2019-03-27T19:16:48Z

From: Tony Jones <tonyj@suse.de>

[ Upstream commit cc437642255224e4140fed1f3e3156fc8ad91903 ]

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

Use a non-const variable to pass the 'name' arg to
PyImport_AppendInittab(), as python2.6 has that as 'char *', which ends
up trowing this in some environments:

CC /tmp/build/perf/util/parse-branch-options.o
util/scripting-engines/trace-event-python.c: In function 'python_start_script':
util/scripting-engines/trace-event-python.c:1520:2: error: passing argument 1 of 'PyImport_AppendInittab' discards 'const' qualifier from pointer target type [-Werror]
PyImport_AppendInittab("perf_trace_context", initfunc);
^
In file included from /usr/include/python2.6/Python.h:130:0,
from util/scripting-engines/trace-event-python.c:22:
/usr/include/python2.6/import.h:54:17: note: expected 'char *' but argument is of type 'const char *'
PyAPI_FUNC(int) PyImport_AppendInittab(char *name, void (*initfunc)(void));
^
cc1: all warnings being treated as errors

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../perf/util/scripting-engines/trace-event-python.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
index 2fe3cc43526f..7059d1be2d09 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -1493,34 +1493,40 @@ 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
wchar_t **command_line;
#endif
- char buf[PATH_MAX];
+ /*
+ * Use a non-const name variable to cope with python 2.6's
+ * PyImport_AppendInittab prototype
+ */
+ char buf[PATH_MAX], name[19] = "perf_trace_context";
int i, err = 0;
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(name, 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

--
2.19.1