[PATCH 5.9 252/255] perf scripting python: Avoid declaring function pointers with a visibility attribute

Greg Kroah-Hartman
2020-11-17T13:43:05Z

From: Arnaldo Carvalho de Melo <acme@redhat.com>

commit d0e7b0c71fbb653de90a7163ef46912a96f0bdaf upstream.

To avoid this:

util/scripting-engines/trace-event-python.c: In function 'python_start_script':
util/scripting-engines/trace-event-python.c:1595:2: error: 'visibility' attribute ignored [-Werror=attributes]
1595 | PyMODINIT_FUNC (*initfunc)(void);
| ^~~~~~~~~~~~~~

That started breaking when building with PYTHON=python3 and these gcc
versions (I haven't checked with the clang ones, maybe it breaks there
as well):

# export PERF_TARBALL=http://192.168.86.5/perf/perf-5.9.0.tar.xz
# dm fedora:33 fedora:rawhide
1 107.80 fedora:33 : Ok gcc (GCC) 10.2.1 20201005 (Red Hat 10.2.1-5), clang version 11.0.0 (Fedora 11.0.0-1.fc33)
2 92.47 fedora:rawhide : Ok gcc (GCC) 10.2.1 20201016 (Red Hat 10.2.1-6), clang version 11.0.0 (Fedora 11.0.0-1.fc34)
#

Avoid that by ditching that 'initfunc' function pointer with its:

#define Py_EXPORTED_SYMBOL _attribute_ ((visibility ("default")))
#define PyMODINIT_FUNC Py_EXPORTED_SYMBOL PyObject*

And just call PyImport_AppendInittab() at the end of the ifdef python3
block with the functions that were being attributed to that initfunc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Tapas Kundu <tkundu@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
tools/perf/util/scripting-engines/trace-event-python.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -1592,7 +1592,6 @@ static void _free_command_line(wchar_t *
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
@@ -1607,20 +1606,18 @@ static int python_start_script(const cha
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];
+ PyImport_AppendInittab(name, initperf_trace_context);
#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);
+ PyImport_AppendInittab(name, PyInit_perf_trace_context);
#endif
-
- PyImport_AppendInittab(name, initfunc);
Py_Initialize();

#if PY_MAJOR_VERSION < 3