[PATCH V4 1/2] powerpc tools perf: Initialize error code in auxtrace_record_init function

[PATCH V4 1/2] powerpc tools perf: Initialize error code in auxtrace_record_init function

[Athira Rajeev]

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: 1dbfaf94cf66 ("perf powerpc: Add basic CONFIG_AUXTRACE support for VPA pmu on powerpc")
Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>
---
Changelog:
v1 -> v2
Addressed review comment from Adrian:
- Set err to -EINVAL before invoking auxtrace_record__init() in
  builtin-record.c
- Added kernel-doc to auxtrace_record__init() in tools/perf/util/auxtrace.c
Addressed review comment from Namhyung:
- Added fixes tag

 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 e39deff6c857..4600a1661b4f 100644
--- a/tools/perf/arch/powerpc/util/auxtrace.c
+++ b/tools/perf/arch/powerpc/util/auxtrace.c
@@ -71,6 +71,12 @@ 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 4a5eba498c02..708825747af5 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -865,6 +865,7 @@ 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;
-- 
2.47.3

[PATCH V4 2/2] tools/perf: Add kernel-doc comment to auxtrace_record__init() function

[Athira Rajeev]

Add documentation comment describing the parameters
and return code for auxtrace_record__init() in util/auxtrace.c

Using "struct evlist *evlist __maybe_unused", gives below
warning with "scripts/kernel-doc".

 # ./scripts/kernel-doc -none tools/perf/util/auxtrace.c
 Warning: tools/perf/util/auxtrace.c:912 function parameter '__maybe_unused' not described in 'auxtrace_record__init'
 Warning: tools/perf/util/auxtrace.c:912 function parameter '__maybe_unused' not described in 'auxtrace_record__init'

Updated  parameter as "struct evlist __maybe_unused *evlist"
With the change, there is no erros/warnings with kernel-doc

Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>
---
Changelog:
v3 -> v4:
Addressed review comment from Sashiko:
Update return value expectation for fail as
non zero return err code.

v2 -> v3:
Addressed review comment from Sashiko:
Update return value expectation for success and fail
correctly.

 tools/perf/util/auxtrace.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index a224687ffbc1..9e11cf4299b8 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -896,8 +896,23 @@ int auxtrace_parse_aux_action(struct evlist *evlist)
 	return 0;
 }
 
+/**
+ * auxtrace_record__init - Initialize an AUX area tracing record.
+ * @evlist: The list of events to check for AUX area tracing event.
+ * @err: Pointer to an integer to store return code.
+ *
+ * This function looks through the @evlist to determine which AUX area
+ * tracing hardware is being used and initializes the auxtrace_record
+ * structure.
+ *
+ * Return:
+ * a) A pointer to the struct auxtrace_record on success.
+ * b) NULL with @err = 0 if no AUX area tracing event is found/supported
+ *    (not considered an error).
+ * c) NULL with non-zero @err on actual auxtrace_record__init failure.
+ */
 struct auxtrace_record *__weak
-auxtrace_record__init(struct evlist *evlist __maybe_unused, int *err)
+auxtrace_record__init(struct evlist __maybe_unused *evlist, int *err)
 {
 	*err = 0;
 	return NULL;
-- 
2.47.3

Re: [PATCH V4 2/2] tools/perf: Add kernel-doc comment to auxtrace_record__init() function

[Namhyung Kim]

Hello,

On Sat, May 02, 2026 at 08:02:37PM +0530, Athira Rajeev wrote:
> Add documentation comment describing the parameters
> and return code for auxtrace_record__init() in util/auxtrace.c
> 
> Using "struct evlist *evlist __maybe_unused", gives below
> warning with "scripts/kernel-doc".
> 
>  # ./scripts/kernel-doc -none tools/perf/util/auxtrace.c
>  Warning: tools/perf/util/auxtrace.c:912 function parameter '__maybe_unused' not described in 'auxtrace_record__init'
>  Warning: tools/perf/util/auxtrace.c:912 function parameter '__maybe_unused' not described in 'auxtrace_record__init'
> 
> Updated  parameter as "struct evlist __maybe_unused *evlist"
> With the change, there is no erros/warnings with kernel-doc

Hmm.. this is not what we used to have.  I'm not sure if we want to
update them all.  Maybe better to leave it for now.

> 
> Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>
> ---
> Changelog:
> v3 -> v4:
> Addressed review comment from Sashiko:
> Update return value expectation for fail as
> non zero return err code.
> 
> v2 -> v3:
> Addressed review comment from Sashiko:
> Update return value expectation for success and fail
> correctly.
> 
>  tools/perf/util/auxtrace.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
> index a224687ffbc1..9e11cf4299b8 100644
> --- a/tools/perf/util/auxtrace.c
> +++ b/tools/perf/util/auxtrace.c
> @@ -896,8 +896,23 @@ int auxtrace_parse_aux_action(struct evlist *evlist)
>  	return 0;
>  }
>  
> +/**
> + * auxtrace_record__init - Initialize an AUX area tracing record.
> + * @evlist: The list of events to check for AUX area tracing event.
> + * @err: Pointer to an integer to store return code.
> + *
> + * This function looks through the @evlist to determine which AUX area
> + * tracing hardware is being used and initializes the auxtrace_record
> + * structure.
> + *
> + * Return:
> + * a) A pointer to the struct auxtrace_record on success.

I think you should mention that the this function should set *err to
zero on success.

Thanks,
Namhyung


> + * b) NULL with @err = 0 if no AUX area tracing event is found/supported
> + *    (not considered an error).
> + * c) NULL with non-zero @err on actual auxtrace_record__init failure.
> + */
>  struct auxtrace_record *__weak
> -auxtrace_record__init(struct evlist *evlist __maybe_unused, int *err)
> +auxtrace_record__init(struct evlist __maybe_unused *evlist, int *err)
>  {
>  	*err = 0;
>  	return NULL;
> -- 
> 2.47.3
> 

Re: [PATCH V4 2/2] tools/perf: Add kernel-doc comment to auxtrace_record__init() function

[Athira Rajeev]

> On 4 May 2026, at 7:16 AM, Namhyung Kim <namhyung@kernel.org> wrote:
> 
> Hello,
> 
> On Sat, May 02, 2026 at 08:02:37PM +0530, Athira Rajeev wrote:
>> Add documentation comment describing the parameters
>> and return code for auxtrace_record__init() in util/auxtrace.c
>> 
>> Using "struct evlist *evlist __maybe_unused", gives below
>> warning with "scripts/kernel-doc".
>> 
>> # ./scripts/kernel-doc -none tools/perf/util/auxtrace.c
>> Warning: tools/perf/util/auxtrace.c:912 function parameter '__maybe_unused' not described in 'auxtrace_record__init'
>> Warning: tools/perf/util/auxtrace.c:912 function parameter '__maybe_unused' not described in 'auxtrace_record__init'
>> 
>> Updated  parameter as "struct evlist __maybe_unused *evlist"
>> With the change, there is no erros/warnings with kernel-doc
> 
> Hmm.. this is not what we used to have.  I'm not sure if we want to
> update them all.  Maybe better to leave it for now.

Sure, I will keep it as original version.

> 
>> 
>> Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>
>> ---
>> Changelog:
>> v3 -> v4:
>> Addressed review comment from Sashiko:
>> Update return value expectation for fail as
>> non zero return err code.
>> 
>> v2 -> v3:
>> Addressed review comment from Sashiko:
>> Update return value expectation for success and fail
>> correctly.
>> 
>> tools/perf/util/auxtrace.c | 17 ++++++++++++++++-
>> 1 file changed, 16 insertions(+), 1 deletion(-)
>> 
>> diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
>> index a224687ffbc1..9e11cf4299b8 100644
>> --- a/tools/perf/util/auxtrace.c
>> +++ b/tools/perf/util/auxtrace.c
>> @@ -896,8 +896,23 @@ int auxtrace_parse_aux_action(struct evlist *evlist)
>> return 0;
>> }
>> 
>> +/**
>> + * auxtrace_record__init - Initialize an AUX area tracing record.
>> + * @evlist: The list of events to check for AUX area tracing event.
>> + * @err: Pointer to an integer to store return code.
>> + *
>> + * This function looks through the @evlist to determine which AUX area
>> + * tracing hardware is being used and initializes the auxtrace_record
>> + * structure.
>> + *
>> + * Return:
>> + * a) A pointer to the struct auxtrace_record on success.
> 
> I think you should mention that the this function should set *err to
> zero on success.
Sure, I will update this 

Thanks
Athira
> 
> Thanks,
> Namhyung
> 
> 
>> + * b) NULL with @err = 0 if no AUX area tracing event is found/supported
>> + *    (not considered an error).
>> + * c) NULL with non-zero @err on actual auxtrace_record__init failure.
>> + */
>> struct auxtrace_record *__weak
>> -auxtrace_record__init(struct evlist *evlist __maybe_unused, int *err)
>> +auxtrace_record__init(struct evlist __maybe_unused *evlist, int *err)
>> {
>> *err = 0;
>> return NULL;
>> -- 
>> 2.47.3

Re: [PATCH V4 1/2] powerpc tools perf: Initialize error code in auxtrace_record_init function

[Adrian Hunter]

On 02/05/2026 17:32, 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) {
>                 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: 1dbfaf94cf66 ("perf powerpc: Add basic CONFIG_AUXTRACE support for VPA pmu on powerpc")
> Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>

Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
> Changelog:
> v1 -> v2
> Addressed review comment from Adrian:
> - Set err to -EINVAL before invoking auxtrace_record__init() in
>   builtin-record.c
> - Added kernel-doc to auxtrace_record__init() in tools/perf/util/auxtrace.c
> Addressed review comment from Namhyung:
> - Added fixes tag
> 
>  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 e39deff6c857..4600a1661b4f 100644
> --- a/tools/perf/arch/powerpc/util/auxtrace.c
> +++ b/tools/perf/arch/powerpc/util/auxtrace.c
> @@ -71,6 +71,12 @@ 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 4a5eba498c02..708825747af5 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -865,6 +865,7 @@ 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;