[tip:perf/core] perf config: Honour $PERF_CONFIG env var to specify alternate .perfconfig

[tip-bot for Arnaldo Carvalho de Melo]

Commit-ID:  61a461fcbd62d42c29a1ea6a9cc3838ad9f49401
Gitweb:     https://git.kernel.org/tip/61a461fcbd62d42c29a1ea6a9cc3838ad9f49401
Author:     Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
AuthorDate: Tue, 30 Jul 2019 11:20:55 -0300
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 12 Aug 2019 16:26:02 -0300

perf config: Honour $PERF_CONFIG env var to specify alternate .perfconfig

We had this comment in Documentation/perf_counter/config.c, i.e. since
when we got this from the git sources, but never really did that
getenv("PERF_CONFIG"), do it now as I need to disable whatever
~/.perfconfig root has so that tests parsing tool output are done for
the expected default output or that we specify an alternate config file
that when read will make the tools produce expected output.

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Luis ClÃudio GonÃalves <lclaudio@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Taeung Song <treeze.taeung@xxxxxxxxx>
Fixes: 078006012401 ("perf_counter tools: add in basic glue from Git")
Link: https://lkml.kernel.org/n/tip-jo209zac9rut0dz1rqvbdlgm@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/perf.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 97e2628ea5dd..d4e4d53e8b44 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -441,6 +441,9 @@ int main(int argc, const char **argv)
 
 	srandom(time(NULL));
 
+	/* Setting $PERF_CONFIG makes perf read _only_ the given config file. */
+	config_exclusive_filename = getenv("PERF_CONFIG");
+
 	err = perf_config(perf_default_config, NULL);
 	if (err)
 		return err;