Re: [PATCH] powerpc tools perf: Initialize error code in auxtrace_record_init function

[Adrian Hunter <adrian.hunter@intel.com>]

On 26/04/2026 09:43, Athira Rajeev wrote:
> 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) {

Perhaps also add here:

                  err = -EINVAL;
		
>                 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.
> 
> 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) ]
> 
> Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>
> ---
>  tools/perf/arch/powerpc/util/auxtrace.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/tools/perf/arch/powerpc/util/auxtrace.c b/tools/perf/arch/powerpc/util/auxtrace.c
> index e39deff6c857..fe1ea4e222f3 100644
> --- a/tools/perf/arch/powerpc/util/auxtrace.c
> +++ b/tools/perf/arch/powerpc/util/auxtrace.c
> @@ -71,6 +71,19 @@ struct auxtrace_record *auxtrace_record__init(struct evlist *evlist,
>  	struct evsel *pos;
>  	int found = 0;
>  
> +	/*
> +	 * Assign err value to zero here. 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.
> +	 */

Comment seems like overkill.  Prefer to add kernel-doc to
auxtrace_record__init() in tools/perf/util/auxtrace.c

> +	*err = 0;
> +
>  	evlist__for_each_entry(evlist, pos) {
>  		if (strstarts(pos->name, "vpa_dtl")) {
>  			found = 1;