[PATCH 6.18 0617/1611] powerpc tools perf: Initialize error code in auxtrace_record_init function

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Athira Rajeev <redacted>

[ Upstream commit 789d22d77879eabb042627f6627cdb62787bc142 ]

perf trace record fails some cases in powerpc

 # perf test "perf trace record and replay"
 128: perf trace record and replay                                    : FAILED!

  # perf trace record sleep 1
  # echo $?
    32

This is happening because of non-zero err value from
auxtrace_record__init() function.

 static int record__auxtrace_init(struct record *rec)
 {
        int err;

        if ((rec->opts.auxtrace_snapshot_opts || rec->opts.auxtrace_sample_opts)
            && record__threads_enabled(rec)) {
                pr_err("AUX area tracing options are not available in parallel streaming mode.\n");
                return -EINVAL;
        }

        if (!rec->itr) {
                rec->itr = auxtrace_record__init(rec->evlist, &err);
                if (err)
                        return err;
        }

Here "int err" is not initialised. The code expects "err" to be set from
auxtrace_record__init() function.

Update auxtrace_record__init() in arch/powerpc/util/auxtrace.c to clear
err value in the beginning.

- Clear err value in beginning of function. Any fail later will
set appropriate return code to err.

- Even if we haven't found any event for auxtrace, perf record
should continue for other events. NULL return
will indicate that there is no auxtrace record initialized.

- Not having "err" set here will affect monitoring of other events
also because perf record will fail seeing random value in err.

Set err to -EINVAL before invoking auxtrace_record__init() in
builtin-record.c

With the fix,

  # perf trace record sleep 1
  [ perf record: Woken up 2 times to write data ]
  [ perf record: Captured and wrote 0.033 MB perf.data (228 samples) ]

Fixes: 1dbfaf94cf66ec4b ("perf powerpc: Add basic CONFIG_AUXTRACE support for VPA pmu on powerpc")
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Athira Rajeev <redacted>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Athira Rajeev <redacted>
Cc: Hari Bathini <redacted>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Petlan <redacted>
Cc: Shivani Nittor <redacted>
Cc: Tanushree Shah <redacted>
Cc: Tejas Manhas <redacted>
Cc: Thomas Richter <redacted>
Signed-off-by: Arnaldo Carvalho de Melo <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/perf/arch/powerpc/util/auxtrace.c | 6 ++++++
 tools/perf/builtin-record.c             | 1 +
 2 files changed, 7 insertions(+)

diff --git a/tools/perf/arch/powerpc/util/auxtrace.c b/tools/perf/arch/powerpc/util/auxtrace.c
index 62c6f67f1bbe66..57f2910c0b0198 100644
--- a/tools/perf/arch/powerpc/util/auxtrace.c
+++ b/tools/perf/arch/powerpc/util/auxtrace.c

@@ -70,6 +70,12 @@ struct auxtrace_record *auxtrace_record__init(struct evlist *evlist,
 	struct evsel *pos;
 	int found = 0;
 
+	/*
+	 * Set err value to zero here. Any fail later
+	 * will set appropriate return code to err.
+	 */
+	*err = 0;
+
 	evlist__for_each_entry(evlist, pos) {
 		if (strstarts(pos->name, "vpa_dtl")) {
 			found = 1;

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index b1fb87016d5aa9..2563ef66a4d946 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c

@@ -867,6 +867,7 @@ static int record__auxtrace_init(struct record *rec)
 	}
 
 	if (!rec->itr) {
+		err = -EINVAL;
 		rec->itr = auxtrace_record__init(rec->evlist, &err);
 		if (err)
 			return err;

-- 
2.53.0