Re: [PATCH v4 1/6] perf config: Use new perf_config_set__init() to initialize config set

From: Taeung Song
Date: Tue May 31 2016 - 12:52:33 EST

On 05/31/2016 10:43 PM, Arnaldo Carvalho de Melo wrote:
Em Tue, May 31, 2016 at 10:13:43AM +0900, Taeung Song escreveu:
Instead of perf_config(), This function initialize config set
collecting all configs from config files (i.e. user config
~/.perfconfig and system config $(sysconfdir)/perfconfig).

If there are the same config variable both user and system
config file, user config has higher priority than system config.

Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Signed-off-by: Taeung Song <treeze.taeung@xxxxxxxxx>
tools/perf/util/config.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
index dad7d82..5d01899 100644
--- a/tools/perf/util/config.c
+++ b/tools/perf/util/config.c
@@ -645,13 +645,61 @@ out_free:
return -1;

+static int perf_config_set__init(struct perf_config_set *set)
+ int ret = 0, found = 0;
+ const char *home = NULL;
+ /* Setting $PERF_CONFIG makes perf read _only_ the given config file. */
+ if (config_exclusive_filename)
+ return perf_config_from_file(collect_config, config_exclusive_filename, set);
+ if (perf_config_system() && !access(perf_etc_perfconfig(), R_OK)) {
+ ret += perf_config_from_file(collect_config, perf_etc_perfconfig(), set);
+ found += 1;
+ }
+ home = getenv("HOME");
+ if (perf_config_global() && home) {
+ char *user_config = strdup(mkpath("%s/.perfconfig", home));
+ struct stat st;
+ if (user_config == NULL) {
+ warning("Not enough memory to process %s/.perfconfig, "
+ "ignoring it.", home);
+ goto out;
+ }
+ if (stat(user_config, &st) < 0)
+ goto out_free;
+ if (st.st_uid && (st.st_uid != geteuid())) {
+ warning("File %s not owned by current user or root, "
+ "ignoring it.", user_config);
+ goto out_free;
+ }
+ if (!st.st_size)
+ goto out_free;
+ ret += perf_config_from_file(collect_config, user_config, set);
+ found += 1;
+ free(user_config);
+ }
+ if (found == 0)
+ return -1;
+ return ret;
struct perf_config_set *perf_config_set__new(void)
struct perf_config_set *set = zalloc(sizeof(*set));

if (set) {
- perf_config(collect_config, set);
+ if (perf_config_set__init(set) < 0)
+ return NULL;

So, the usual pattern is: alloc, init, fail? free, return NULL.

I thought you could've been deviating from that pattern and went to look
at perf_config_set__init() to see if that was doing the freeing in case
of failure, which it shouldn't, it isn't, so I guess this is a leak on
failure, no?

You are right. And I found additional problems.

First of all, as you said, if it is failed in perf_config_set__init(),
the config set wouldn't be freed so this is a leak on failure.

Secondly, if it is failed in perf_parse_file(),
perf_parse_file() cannot return because of die()
so perf_config_from_file() and perf_config()
don't also return. I guess this is abnormal termination
without the freeing.
(The important point of this problem is die() at perf_parse_file())

Thirdly, there are problems that are related to collect_config().
If perf_config_from_file(collect_config,..) is failed
the config set will be freed at collect_config() like below.

static int collect_config(const char *var, const char *value,
void *perf_config_set)


return -1;

And then if calling perf_config_from_file(collect_config,..)
at perf_config_set__init() again,
an error will happen because the config set is NULL at collect_config().
(the error mean NULL pointer exception.)

To conclude,
First of all, I'll send preparatory PATCH set for this patch
to solve the problems i.e.

1) A problem that perf_config() can't return
becuase of die() at perf_parse_file()

2) A problem about the freeing config set at collect_config()

3) NULL pointer exception at collect_config()

And then I will send changed this patch following above patchset.
(to solve a leak when perf_config_set__init() failed)