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 <rnsastry@linux.vnet.ibm.com>
Signed-off-by: Mamatha Inamdar <mamatha4@linux.vnet.ibm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Nageswara R Sastry <rnsastry@linux.vnet.ibm.com>
Acked-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Reviewed-by: Jiri Olsa <jolsa@redhat.com>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jeremie Galarneau <jeremie.galarneau@efficios.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shawn Landden <shawn@git.icu>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Link: http://lore.kernel.org/lkml/20190822071223.17892.45782.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 60cdd383af81..f7d13326b830 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -83,6 +83,7 @@
 #include <unistd.h>
 #include <sys/time.h>
 #include <sys/resource.h>
+#include <linux/err.h>
 
 #include <linux/ctype.h>
 #include <perf/evlist.h>
@@ -1436,9 +1437,9 @@ static int __cmd_record(int argc, const char **argv)
 	}
 
 	session = perf_session__new(data, false, NULL);
-	if (session == NULL) {
-		pr_err("Perf session creation failed.\n");
-		return -1;
+	if (IS_ERR(session)) {
+		pr_err("Perf session creation failed\n");
+		return PTR_ERR(session);
 	}
 
 	init_features(session);
@@ -1635,8 +1636,8 @@ static int __cmd_report(int argc, const char **argv)
 	perf_stat.data.mode = PERF_DATA_MODE_READ;
 
 	session = perf_session__new(&perf_stat.data, false, &perf_stat.tool);
-	if (session == NULL)
-		return -1;
+	if (IS_ERR(session))
+		return PTR_ERR(session);
 
 	perf_stat.session  = session;
 	stat_config.output = stderr;