perf session: Return error code for perf_session__new() function on failure

This patch is to return error code of perf_new_session function on
failure instead of NULL.

Test Results:

Before Fix:

  $ perf c2c report -input
  failed to open nput: No such file or directory

  $ echo $?
  0
  $

After Fix:

  $ perf c2c report -input
  failed to open nput: No such file or directory

  $ echo $?
  254
  $

Committer notes:

Fix 'perf tests topology' case, where we use that TEST_ASSERT_VAL(...,
session), i.e. we need to pass zero in case of failure, which was the
case before when NULL was returned by perf_session__new() for failure,
but now we need to negate the result of IS_ERR(session) to respect that
TEST_ASSERT_VAL) expectation of zero meaning failure.

Reported-by: Nageswara R Sastry <[email protected]>
Signed-off-by: Mamatha Inamdar <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Tested-by: Nageswara R Sastry <[email protected]>
Acked-by: Ravi Bangoria <[email protected]>
Reviewed-by: Jiri Olsa <[email protected]>
Reviewed-by: Mukesh Ojha <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Alexey Budankov <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Jeremie Galarneau <[email protected]>
Cc: Kate Stewart <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Shawn Landden <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tzvetomir Stoyanov <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

1 files changed, 5 insertions, 4 deletions

diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index 827e4800d862..c37a78677955 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -23,6 +23,7 @@
 #include "util/time-utils.h"
 #include "util/annotate.h"
 #include "util/map.h"
+#include <linux/err.h>
 #include <linux/zalloc.h>
 #include <subcmd/pager.h>
 #include <subcmd/parse-options.h>
@@ -1153,9 +1154,9 @@ static int check_file_brstack(void)
 
 	data__for_each_file(i, d) {
 		d->session = perf_session__new(&d->data, false, &pdiff.tool);
-		if (!d->session) {
+		if (IS_ERR(d->session)) {
 			pr_err("Failed to open %s\n", d->data.path);
-			return -1;
+			return PTR_ERR(d->session);
 		}
 
 		has_br_stack = perf_header__has_feat(&d->session->header,
@@ -1185,9 +1186,9 @@ static int __cmd_diff(void)
 
 	data__for_each_file(i, d) {
 		d->session = perf_session__new(&d->data, false, &pdiff.tool);
-		if (!d->session) {
+		if (IS_ERR(d->session)) {
+			ret = PTR_ERR(d->session);
 			pr_err("Failed to open %s\n", d->data.path);
-			ret = -1;
 			goto out_delete;
 		}