powerpc tools perf: Initialize error code in auxtrace_record_init function

powerpc tools perf: Initialize error code in auxtrace_record_init function

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 <atrajeev@linux.ibm.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Athira Rajeev <atrajeev@linux.ibm.com>
Cc: Hari Bathini <hbathini@linux.vnet.ibm.com>
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 <mpetlan@redhat.com>
Cc: Shivani Nittor <shivani@linux.ibm.com>
Cc: Tanushree Shah <tanushree.shah@ibm.com>
Cc: Tejas Manhas <tejas.manhas1@ibm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>