[tip:perf/core] perf evlist: Restore original errno after open failed

[tip-bot for Namhyung Kim]

Commit-ID:  41c21a68308f2f268a01ec1a7fa5f650e320a0f3
Gitweb:     http://git.kernel.org/tip/41c21a68308f2f268a01ec1a7fa5f650e320a0f3
Author:     Namhyung Kim <namhyung.kim@xxxxxxx>
AuthorDate: Thu, 23 Feb 2012 12:13:36 +0900
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 5 Mar 2012 10:15:49 -0300

perf evlist: Restore original errno after open failed

If perf_evsel__open() failed, the errno was set and returned properly.

However since the perf_evlist__open() called close() on fd's for all of
evsel x cpu x thread after the failure, the errno was overridden by
other code (EBADF). So the caller of the function ended up seeing
different error message and getting confused.

Fit it by restoring original return value. Because one of caller of the
function is in the python extension, and it uses system errno
internally, it'd be better restoring the original value rather than
using the return value of the function directly, IMHO (i.e. I'm not a
python expert :)

Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1329966816-23175-1-git-send-email-namhyung.kim@xxxxxxx
Signed-off-by: Namhyung Kim <namhyung.kim@xxxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/evlist.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index f8da9fa..159263d 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -765,6 +765,7 @@ out_err:
 	list_for_each_entry_reverse(evsel, &evlist->entries, node)
 		perf_evsel__close(evsel, ncpus, nthreads);
 
+	errno = -err;
 	return err;
 }
 
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