[PATCH v4 0/1] Perf lock improvements

[PATCH v4 0/1] Perf lock improvements

[Nick Forrington]

Improvement to command line handling for perf lock info.
---
v1: https://lore.kernel.org/all/20231031120526.11502-1-nick.forrington@arm.com/

v2:
* Drop previous "perf lock report: Restore aggregation by caller by
  default" patch. Not required for newly collected data with LOCKDEP
  tracepoints.
* Display map and thread info (rather than an error) when neither or
  both of --map and --thread are specified.

v3:
* Update --help output

v4:
* Remove redundant error handling

Nick Forrington (1):
  perf lock info: Display both map and thread by default

 tools/perf/Documentation/perf-lock.txt |  4 ++--
 tools/perf/builtin-lock.c              | 27 ++++++++++++++------------
 2 files changed, 17 insertions(+), 14 deletions(-)

-- 
2.44.0

[PATCH 1/1] perf lock info: Display both map and thread by default

[Nick Forrington]

Change "perf lock info" argument handling to:

Display both map and thread info (rather than an error) when neither are
specified.

Display both map and thread info (rather than just thread info) when
both are requested.

Signed-off-by: Nick Forrington <nick.forrington@arm.com>
---
 tools/perf/Documentation/perf-lock.txt |  4 ++--
 tools/perf/builtin-lock.c              | 27 ++++++++++++++------------
 2 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/tools/perf/Documentation/perf-lock.txt b/tools/perf/Documentation/perf-lock.txt
index f5938d616d75..57a940399de0 100644
--- a/tools/perf/Documentation/perf-lock.txt
+++ b/tools/perf/Documentation/perf-lock.txt
@@ -111,11 +111,11 @@ INFO OPTIONS
 
 -t::
 --threads::
-	dump thread list in perf.data
+	dump only the thread list in perf.data
 
 -m::
 --map::
-	dump map of lock instances (address:name table)
+	dump only the map of lock instances (address:name table)
 
 
 CONTENTION OPTIONS
diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index 230461280e45..7eb115aeb927 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -1477,20 +1477,16 @@ static void dump_map(void)
 		fprintf(lock_output, " %#llx: %s\n", (unsigned long long)st->addr, st->name);
 }
 
-static int dump_info(void)
+static void dump_info(void)
 {
-	int rc = 0;
-
 	if (info_threads)
 		dump_threads();
-	else if (info_map)
+
+	if (info_map) {
+		if (info_threads)
+			fputc('\n', lock_output);
 		dump_map();
-	else {
-		rc = -1;
-		pr_err("Unknown type of information\n");
 	}
-
-	return rc;
 }
 
 static const struct evsel_str_handler lock_tracepoints[] = {
@@ -1992,7 +1988,7 @@ static int __cmd_report(bool display_info)
 
 	setup_pager();
 	if (display_info) /* used for info subcommand */
-		err = dump_info();
+		dump_info();
 	else {
 		combine_result();
 		sort_result();
@@ -2578,9 +2574,9 @@ int cmd_lock(int argc, const char **argv)
 
 	const struct option info_options[] = {
 	OPT_BOOLEAN('t', "threads", &info_threads,
-		    "dump thread list in perf.data"),
+		    "dump the thread list in perf.data"),
 	OPT_BOOLEAN('m', "map", &info_map,
-		    "map of lock instances (address:name table)"),
+		    "dump the map of lock instances (address:name table)"),
 	OPT_PARENT(lock_options)
 	};
 
@@ -2694,6 +2690,13 @@ int cmd_lock(int argc, const char **argv)
 			if (argc)
 				usage_with_options(info_usage, info_options);
 		}
+
+		/* If neither threads nor map requested, display both */
+		if (!info_threads && !info_map) {
+			info_threads = true;
+			info_map = true;
+		}
+
 		/* recycling report_lock_ops */
 		trace_handler = &report_lock_ops;
 		rc = __cmd_report(true);
-- 
2.44.0

Re: [PATCH 1/1] perf lock info: Display both map and thread by default

[Nick Forrington]

Is this ok to be applied now?

Thanks,
Nick

On 13/05/2024 10:14, Nick Forrington wrote:
> Change "perf lock info" argument handling to:
>
> Display both map and thread info (rather than an error) when neither are
> specified.
>
> Display both map and thread info (rather than just thread info) when
> both are requested.
>
> Signed-off-by: Nick Forrington <nick.forrington@arm.com>
> ---
>   tools/perf/Documentation/perf-lock.txt |  4 ++--
>   tools/perf/builtin-lock.c              | 27 ++++++++++++++------------
>   2 files changed, 17 insertions(+), 14 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-lock.txt b/tools/perf/Documentation/perf-lock.txt
> index f5938d616d75..57a940399de0 100644
> --- a/tools/perf/Documentation/perf-lock.txt
> +++ b/tools/perf/Documentation/perf-lock.txt
> @@ -111,11 +111,11 @@ INFO OPTIONS
>   
>   -t::
>   --threads::
> -	dump thread list in perf.data
> +	dump only the thread list in perf.data
>   
>   -m::
>   --map::
> -	dump map of lock instances (address:name table)
> +	dump only the map of lock instances (address:name table)
>   
>   
>   CONTENTION OPTIONS
> diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> index 230461280e45..7eb115aeb927 100644
> --- a/tools/perf/builtin-lock.c
> +++ b/tools/perf/builtin-lock.c
> @@ -1477,20 +1477,16 @@ static void dump_map(void)
>   		fprintf(lock_output, " %#llx: %s\n", (unsigned long long)st->addr, st->name);
>   }
>   
> -static int dump_info(void)
> +static void dump_info(void)
>   {
> -	int rc = 0;
> -
>   	if (info_threads)
>   		dump_threads();
> -	else if (info_map)
> +
> +	if (info_map) {
> +		if (info_threads)
> +			fputc('\n', lock_output);
>   		dump_map();
> -	else {
> -		rc = -1;
> -		pr_err("Unknown type of information\n");
>   	}
> -
> -	return rc;
>   }
>   
>   static const struct evsel_str_handler lock_tracepoints[] = {
> @@ -1992,7 +1988,7 @@ static int __cmd_report(bool display_info)
>   
>   	setup_pager();
>   	if (display_info) /* used for info subcommand */
> -		err = dump_info();
> +		dump_info();
>   	else {
>   		combine_result();
>   		sort_result();
> @@ -2578,9 +2574,9 @@ int cmd_lock(int argc, const char **argv)
>   
>   	const struct option info_options[] = {
>   	OPT_BOOLEAN('t', "threads", &info_threads,
> -		    "dump thread list in perf.data"),
> +		    "dump the thread list in perf.data"),
>   	OPT_BOOLEAN('m', "map", &info_map,
> -		    "map of lock instances (address:name table)"),
> +		    "dump the map of lock instances (address:name table)"),
>   	OPT_PARENT(lock_options)
>   	};
>   
> @@ -2694,6 +2690,13 @@ int cmd_lock(int argc, const char **argv)
>   			if (argc)
>   				usage_with_options(info_usage, info_options);
>   		}
> +
> +		/* If neither threads nor map requested, display both */
> +		if (!info_threads && !info_map) {
> +			info_threads = true;
> +			info_map = true;
> +		}
> +
>   		/* recycling report_lock_ops */
>   		trace_handler = &report_lock_ops;
>   		rc = __cmd_report(true);

Re: [PATCH 1/1] perf lock info: Display both map and thread by default

[Namhyung Kim]

Hello,

On Mon, Jun 3, 2024 at 2:38 AM Nick Forrington <nick.forrington@arm.com> wrote:
>
> Is this ok to be applied now?

Sorry for the delay.  Yep, it's now applied to perf-tools-next.

Thanks,
Namhyung

>
> On 13/05/2024 10:14, Nick Forrington wrote:
> > Change "perf lock info" argument handling to:
> >
> > Display both map and thread info (rather than an error) when neither are
> > specified.
> >
> > Display both map and thread info (rather than just thread info) when
> > both are requested.
> >
> > Signed-off-by: Nick Forrington <nick.forrington@arm.com>
> > ---
> >   tools/perf/Documentation/perf-lock.txt |  4 ++--
> >   tools/perf/builtin-lock.c              | 27 ++++++++++++++------------
> >   2 files changed, 17 insertions(+), 14 deletions(-)
> >
> > diff --git a/tools/perf/Documentation/perf-lock.txt b/tools/perf/Documentation/perf-lock.txt
> > index f5938d616d75..57a940399de0 100644
> > --- a/tools/perf/Documentation/perf-lock.txt
> > +++ b/tools/perf/Documentation/perf-lock.txt
> > @@ -111,11 +111,11 @@ INFO OPTIONS
> >
> >   -t::
> >   --threads::
> > -     dump thread list in perf.data
> > +     dump only the thread list in perf.data
> >
> >   -m::
> >   --map::
> > -     dump map of lock instances (address:name table)
> > +     dump only the map of lock instances (address:name table)
> >
> >
> >   CONTENTION OPTIONS
> > diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> > index 230461280e45..7eb115aeb927 100644
> > --- a/tools/perf/builtin-lock.c
> > +++ b/tools/perf/builtin-lock.c
> > @@ -1477,20 +1477,16 @@ static void dump_map(void)
> >               fprintf(lock_output, " %#llx: %s\n", (unsigned long long)st->addr, st->name);
> >   }
> >
> > -static int dump_info(void)
> > +static void dump_info(void)
> >   {
> > -     int rc = 0;
> > -
> >       if (info_threads)
> >               dump_threads();
> > -     else if (info_map)
> > +
> > +     if (info_map) {
> > +             if (info_threads)
> > +                     fputc('\n', lock_output);
> >               dump_map();
> > -     else {
> > -             rc = -1;
> > -             pr_err("Unknown type of information\n");
> >       }
> > -
> > -     return rc;
> >   }
> >
> >   static const struct evsel_str_handler lock_tracepoints[] = {
> > @@ -1992,7 +1988,7 @@ static int __cmd_report(bool display_info)
> >
> >       setup_pager();
> >       if (display_info) /* used for info subcommand */
> > -             err = dump_info();
> > +             dump_info();
> >       else {
> >               combine_result();
> >               sort_result();
> > @@ -2578,9 +2574,9 @@ int cmd_lock(int argc, const char **argv)
> >
> >       const struct option info_options[] = {
> >       OPT_BOOLEAN('t', "threads", &info_threads,
> > -                 "dump thread list in perf.data"),
> > +                 "dump the thread list in perf.data"),
> >       OPT_BOOLEAN('m', "map", &info_map,
> > -                 "map of lock instances (address:name table)"),
> > +                 "dump the map of lock instances (address:name table)"),
> >       OPT_PARENT(lock_options)
> >       };
> >
> > @@ -2694,6 +2690,13 @@ int cmd_lock(int argc, const char **argv)
> >                       if (argc)
> >                               usage_with_options(info_usage, info_options);
> >               }
> > +
> > +             /* If neither threads nor map requested, display both */
> > +             if (!info_threads && !info_map) {
> > +                     info_threads = true;
> > +                     info_map = true;
> > +             }
> > +
> >               /* recycling report_lock_ops */
> >               trace_handler = &report_lock_ops;
> >               rc = __cmd_report(true);

[PATCH v3 0/1] Perf lock improvements

[Nick Forrington]

Improvement to command line handling for perf lock info.
---
v1: https://lore.kernel.org/all/20231031120526.11502-1-nick.forrington@arm.com/

v2:
* Drop previous "perf lock report: Restore aggregation by caller by
  default" patch. Not required for newly collected data with LOCKDEP
  tracepoints.
* Display map and thread info (rather than an error) when neither or
  both of --map and --thread are specified.

v3:
* Update --help output

Nick Forrington (1):
  perf lock info: Display both map and thread by default

 tools/perf/Documentation/perf-lock.txt |  4 ++--
 tools/perf/builtin-lock.c              | 22 +++++++++++++++++-----
 2 files changed, 19 insertions(+), 7 deletions(-)

-- 
2.44.0

[PATCH 1/1] perf lock info: Display both map and thread by default

[Nick Forrington]

Change "perf lock info" argument handling to:

Display both map and thread info (rather than an error) when neither are
specified.

Display both map and thread info (rather than just thread info) when
both are requested.

Signed-off-by: Nick Forrington <nick.forrington@arm.com>
---
 tools/perf/Documentation/perf-lock.txt |  4 ++--
 tools/perf/builtin-lock.c              | 22 +++++++++++++++++-----
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/tools/perf/Documentation/perf-lock.txt b/tools/perf/Documentation/perf-lock.txt
index f5938d616d75..57a940399de0 100644
--- a/tools/perf/Documentation/perf-lock.txt
+++ b/tools/perf/Documentation/perf-lock.txt
@@ -111,11 +111,11 @@ INFO OPTIONS
 
 -t::
 --threads::
-	dump thread list in perf.data
+	dump only the thread list in perf.data
 
 -m::
 --map::
-	dump map of lock instances (address:name table)
+	dump only the map of lock instances (address:name table)
 
 
 CONTENTION OPTIONS
diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index 230461280e45..d0b8645487ad 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -1483,11 +1483,16 @@ static int dump_info(void)
 
 	if (info_threads)
 		dump_threads();
-	else if (info_map)
+
+	if (info_map) {
+		if (info_threads)
+			fputc('\n', lock_output);
 		dump_map();
-	else {
+	}
+
+	if (!info_threads && !info_map) {
 		rc = -1;
-		pr_err("Unknown type of information\n");
+		pr_err("No lock info specified\n");
 	}
 
 	return rc;
@@ -2578,9 +2583,9 @@ int cmd_lock(int argc, const char **argv)
 
 	const struct option info_options[] = {
 	OPT_BOOLEAN('t', "threads", &info_threads,
-		    "dump thread list in perf.data"),
+		    "dump the thread list in perf.data"),
 	OPT_BOOLEAN('m', "map", &info_map,
-		    "map of lock instances (address:name table)"),
+		    "dump the map of lock instances (address:name table)"),
 	OPT_PARENT(lock_options)
 	};
 
@@ -2694,6 +2699,13 @@ int cmd_lock(int argc, const char **argv)
 			if (argc)
 				usage_with_options(info_usage, info_options);
 		}
+
+		/* If neither threads nor map requested, display both */
+		if (!info_threads && !info_map) {
+			info_threads = true;
+			info_map = true;
+		}
+
 		/* recycling report_lock_ops */
 		trace_handler = &report_lock_ops;
 		rc = __cmd_report(true);
-- 
2.44.0

Re: [PATCH 1/1] perf lock info: Display both map and thread by default

[Namhyung Kim]

Hello,

On Wed, May 8, 2024 at 6:46 AM Nick Forrington <nick.forrington@arm.com> wrote:
>
> Change "perf lock info" argument handling to:
>
> Display both map and thread info (rather than an error) when neither are
> specified.
>
> Display both map and thread info (rather than just thread info) when
> both are requested.
>
> Signed-off-by: Nick Forrington <nick.forrington@arm.com>
> ---
>  tools/perf/Documentation/perf-lock.txt |  4 ++--
>  tools/perf/builtin-lock.c              | 22 +++++++++++++++++-----
>  2 files changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-lock.txt b/tools/perf/Documentation/perf-lock.txt
> index f5938d616d75..57a940399de0 100644
> --- a/tools/perf/Documentation/perf-lock.txt
> +++ b/tools/perf/Documentation/perf-lock.txt
> @@ -111,11 +111,11 @@ INFO OPTIONS
>
>  -t::
>  --threads::
> -       dump thread list in perf.data
> +       dump only the thread list in perf.data
>
>  -m::
>  --map::
> -       dump map of lock instances (address:name table)
> +       dump only the map of lock instances (address:name table)
>
>
>  CONTENTION OPTIONS
> diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> index 230461280e45..d0b8645487ad 100644
> --- a/tools/perf/builtin-lock.c
> +++ b/tools/perf/builtin-lock.c
> @@ -1483,11 +1483,16 @@ static int dump_info(void)
>
>         if (info_threads)
>                 dump_threads();
> -       else if (info_map)
> +
> +       if (info_map) {
> +               if (info_threads)
> +                       fputc('\n', lock_output);

it seems you need pr_info("\n").  Where does lock_output come from?


>                 dump_map();
> -       else {
> +       }
> +
> +       if (!info_threads && !info_map) {
>                 rc = -1;
> -               pr_err("Unknown type of information\n");
> +               pr_err("No lock info specified\n");
>         }

I think we can remove this block now.

Thanks,
Namhyung


>
>         return rc;
> @@ -2578,9 +2583,9 @@ int cmd_lock(int argc, const char **argv)
>
>         const struct option info_options[] = {
>         OPT_BOOLEAN('t', "threads", &info_threads,
> -                   "dump thread list in perf.data"),
> +                   "dump the thread list in perf.data"),
>         OPT_BOOLEAN('m', "map", &info_map,
> -                   "map of lock instances (address:name table)"),
> +                   "dump the map of lock instances (address:name table)"),
>         OPT_PARENT(lock_options)
>         };
>
> @@ -2694,6 +2699,13 @@ int cmd_lock(int argc, const char **argv)
>                         if (argc)
>                                 usage_with_options(info_usage, info_options);
>                 }
> +
> +               /* If neither threads nor map requested, display both */
> +               if (!info_threads && !info_map) {
> +                       info_threads = true;
> +                       info_map = true;
> +               }
> +
>                 /* recycling report_lock_ops */
>                 trace_handler = &report_lock_ops;
>                 rc = __cmd_report(true);
> --
> 2.44.0
>
>

Re: [PATCH 1/1] perf lock info: Display both map and thread by default

[Nick Forrington]

Hello,

On 08/05/2024 22:18, Namhyung Kim wrote:
> Hello,
>
> On Wed, May 8, 2024 at 6:46 AM Nick Forrington <nick.forrington@arm.com> wrote:
>> Change "perf lock info" argument handling to:
>>
>> Display both map and thread info (rather than an error) when neither are
>> specified.
>>
>> Display both map and thread info (rather than just thread info) when
>> both are requested.
>>
>> Signed-off-by: Nick Forrington <nick.forrington@arm.com>
>> ---
>>   tools/perf/Documentation/perf-lock.txt |  4 ++--
>>   tools/perf/builtin-lock.c              | 22 +++++++++++++++++-----
>>   2 files changed, 19 insertions(+), 7 deletions(-)
>>
>> diff --git a/tools/perf/Documentation/perf-lock.txt b/tools/perf/Documentation/perf-lock.txt
>> index f5938d616d75..57a940399de0 100644
>> --- a/tools/perf/Documentation/perf-lock.txt
>> +++ b/tools/perf/Documentation/perf-lock.txt
>> @@ -111,11 +111,11 @@ INFO OPTIONS
>>
>>   -t::
>>   --threads::
>> -       dump thread list in perf.data
>> +       dump only the thread list in perf.data
>>
>>   -m::
>>   --map::
>> -       dump map of lock instances (address:name table)
>> +       dump only the map of lock instances (address:name table)
>>
>>
>>   CONTENTION OPTIONS
>> diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
>> index 230461280e45..d0b8645487ad 100644
>> --- a/tools/perf/builtin-lock.c
>> +++ b/tools/perf/builtin-lock.c
>> @@ -1483,11 +1483,16 @@ static int dump_info(void)
>>
>>          if (info_threads)
>>                  dump_threads();
>> -       else if (info_map)
>> +
>> +       if (info_map) {
>> +               if (info_threads)
>> +                       fputc('\n', lock_output);
> it seems you need pr_info("\n").  Where does lock_output come from?


It's a static FILE* that defaults to stderr.


It's used by dump_threads and dump_map (via fprintf), so I think it 
makes sense to use it for the output spacing between them?

>
>
>>                  dump_map();
>> -       else {
>> +       }
>> +
>> +       if (!info_threads && !info_map) {
>>                  rc = -1;
>> -               pr_err("Unknown type of information\n");
>> +               pr_err("No lock info specified\n");
>>          }
> I think we can remove this block now.


The original error looked like a function input sanity check (rather 
than for handling user input), so I kept it (even if it should no longer 
be possible for a user to trigger it).


Although I can remove it (or move it to the start of the function) if 
you prefer.


Thanks,
Nick

>
> Thanks,
> Namhyung
>
>
>>          return rc;
>> @@ -2578,9 +2583,9 @@ int cmd_lock(int argc, const char **argv)
>>
>>          const struct option info_options[] = {
>>          OPT_BOOLEAN('t', "threads", &info_threads,
>> -                   "dump thread list in perf.data"),
>> +                   "dump the thread list in perf.data"),
>>          OPT_BOOLEAN('m', "map", &info_map,
>> -                   "map of lock instances (address:name table)"),
>> +                   "dump the map of lock instances (address:name table)"),
>>          OPT_PARENT(lock_options)
>>          };
>>
>> @@ -2694,6 +2699,13 @@ int cmd_lock(int argc, const char **argv)
>>                          if (argc)
>>                                  usage_with_options(info_usage, info_options);
>>                  }
>> +
>> +               /* If neither threads nor map requested, display both */
>> +               if (!info_threads && !info_map) {
>> +                       info_threads = true;
>> +                       info_map = true;
>> +               }
>> +
>>                  /* recycling report_lock_ops */
>>                  trace_handler = &report_lock_ops;
>>                  rc = __cmd_report(true);
>> --
>> 2.44.0
>>
>>

Re: [PATCH 1/1] perf lock info: Display both map and thread by default

[Namhyung Kim]

On Thu, May 9, 2024 at 3:01 AM Nick Forrington <nick.forrington@arm.com> wrote:
>
> Hello,
>
> On 08/05/2024 22:18, Namhyung Kim wrote:
> > Hello,
> >
> > On Wed, May 8, 2024 at 6:46 AM Nick Forrington <nick.forrington@arm.com> wrote:
> >> Change "perf lock info" argument handling to:
> >>
> >> Display both map and thread info (rather than an error) when neither are
> >> specified.
> >>
> >> Display both map and thread info (rather than just thread info) when
> >> both are requested.
> >>
> >> Signed-off-by: Nick Forrington <nick.forrington@arm.com>
> >> ---
> >>   tools/perf/Documentation/perf-lock.txt |  4 ++--
> >>   tools/perf/builtin-lock.c              | 22 +++++++++++++++++-----
> >>   2 files changed, 19 insertions(+), 7 deletions(-)
> >>
> >> diff --git a/tools/perf/Documentation/perf-lock.txt b/tools/perf/Documentation/perf-lock.txt
> >> index f5938d616d75..57a940399de0 100644
> >> --- a/tools/perf/Documentation/perf-lock.txt
> >> +++ b/tools/perf/Documentation/perf-lock.txt
> >> @@ -111,11 +111,11 @@ INFO OPTIONS
> >>
> >>   -t::
> >>   --threads::
> >> -       dump thread list in perf.data
> >> +       dump only the thread list in perf.data
> >>
> >>   -m::
> >>   --map::
> >> -       dump map of lock instances (address:name table)
> >> +       dump only the map of lock instances (address:name table)
> >>
> >>
> >>   CONTENTION OPTIONS
> >> diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> >> index 230461280e45..d0b8645487ad 100644
> >> --- a/tools/perf/builtin-lock.c
> >> +++ b/tools/perf/builtin-lock.c
> >> @@ -1483,11 +1483,16 @@ static int dump_info(void)
> >>
> >>          if (info_threads)
> >>                  dump_threads();
> >> -       else if (info_map)
> >> +
> >> +       if (info_map) {
> >> +               if (info_threads)
> >> +                       fputc('\n', lock_output);
> > it seems you need pr_info("\n").  Where does lock_output come from?
>
>
> It's a static FILE* that defaults to stderr.

Oh, right.  I somehow confused this with perf sched. ;-p

>
>
> It's used by dump_threads and dump_map (via fprintf), so I think it
> makes sense to use it for the output spacing between them?
>
> >
> >
> >>                  dump_map();
> >> -       else {
> >> +       }
> >> +
> >> +       if (!info_threads && !info_map) {
> >>                  rc = -1;
> >> -               pr_err("Unknown type of information\n");
> >> +               pr_err("No lock info specified\n");
> >>          }
> > I think we can remove this block now.
>
>
> The original error looked like a function input sanity check (rather
> than for handling user input), so I kept it (even if it should no longer
> be possible for a user to trigger it).
>
>
> Although I can remove it (or move it to the start of the function) if
> you prefer.

Yep, I think we can just remove it.

Thanks,
Namhyung