[tip:perf/core] perf config: Allow creating empty config set for config file autogeneration

[tip-bot for Taeung Song]

Commit-ID:  55421b4fb7054f85274b1b6a321e204dac696133
Gitweb:     http://git.kernel.org/tip/55421b4fb7054f85274b1b6a321e204dac696133
Author:     Taeung Song <treeze.taeung@xxxxxxxxx>
AuthorDate: Thu, 7 Sep 2017 12:18:56 +0900
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Wed, 13 Sep 2017 09:49:16 -0300

perf config: Allow creating empty config set for config file autogeneration

When there isn't a config file (e.g. ~/.perfconfig) or it has nothing,
the config set wasn't created.

If the config set does not exist, a config file can't be autogenerated.

So allow creating a empty config set in the above case,
then we can support the config file autogeneration.

Before:

  $ rm -f ~/.perfconfig
  $ perf config --user report.children=false

  $ cat ~/.perfconfig
  cat: /root/.perfconfig: No such file or directory

But I think it should work even if there isn't a config file.

After:

  $ rm -f ~/.perfconfig
  $ perf config --user report.children=false

  $ cat ~/.perfconfig
  # this file is auto-generated.
  [report]
      children = false

NOTE:

As a result, if perf_config_set__init() fails, it looks as if the config
set isn't freed. But it isn't a problem.  Because the config set will be
freed by perf_config_set__delete() at the end of cmd_config().

Signed-off-by: Taeung Song <treeze.taeung@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1504754336-9824-1-git-send-email-treeze.taeung@xxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/config.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
index bc75596..d2b6983 100644
--- a/tools/perf/util/config.c
+++ b/tools/perf/util/config.c
@@ -700,10 +700,7 @@ struct perf_config_set *perf_config_set__new(void)
 
 	if (set) {
 		INIT_LIST_HEAD(&set->sections);
-		if (perf_config_set__init(set) < 0) {
-			perf_config_set__delete(set);
-			set = NULL;
-		}
+		perf_config_set__init(set);
 	}
 
 	return set;