Re: [PATCH 1/1] perf tests hwmon_pmu: Use PRIu64 + (u64) cast for a __u64 field to work more widely

[Ian Rogers]

On Thu, May 28, 2026 at 12:53 PM Arnaldo Carvalho de Melo
<arnaldo.melo@xxxxxxxxx> wrote:
>
> While testing perf with an updated Debian experimental cross compiler
> (gcc version 14.2.0 (Debian 14.2.0-13)) this started failing:
>
>   In file included from tests/hwmon_pmu.c:12:
>   tests/hwmon_pmu.c: In function 'do_test':
>   tests/hwmon_pmu.c:199:34: error: format '%lld' expects argument of type 'long long int', but argument 7 has type '__u64' {aka 'long unsigned int'} [-Werror=format=]
>     199 |                         pr_debug("FAILED %s:%d Unexpected config for '%s', %lld != %ld\n",
>         |                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   /git/perf-7.1.0-rc5/tools/perf/util/debug.h:20:21: note: in definition of macro 'pr_fmt'
>      20 | #define pr_fmt(fmt) fmt
>         |                     ^~~
>   tests/hwmon_pmu.c:199:25: note: in expansion of macro 'pr_debug'
>     199 |                         pr_debug("FAILED %s:%d Unexpected config for '%s', %lld != %ld\n",
>         |                         ^~~~~~~~
>   tests/hwmon_pmu.c:199:79: note: format string is defined here
>     199 |                         pr_debug("FAILED %s:%d Unexpected config for '%s', %lld != %ld\n",
>         |                                                                            ~~~^
>         |                                                                               |
>         |                                                                               long long int
>         |                                                                            %ld
>     LD      /tmp/build/perf/util/intel-pt-decoder/perf-util-in.o
>
> The usual make that %lld a PRIu64 (since arg7 is
> evsel->core.attr.config, which is a __u64) but then on Fedora 44 (gcc
> version 16.1.1 20260515 (Red Hat 16.1.1-2)) it ends up with:
>
>   In file included from tests/hwmon_pmu.c:13:
>   tests/hwmon_pmu.c: In function ‘do_test’:
>   tests/hwmon_pmu.c:200:34: error: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 7 has type ‘__u64’ {aka ‘long long unsigned int’} [-Werror=format=]
>     200 |                         pr_debug("FAILED %s:%d Unexpected config for '%s', %" PRIu64 " != %ld\n",
>         |                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   /home/acme/git/perf-tools-next2/tools/perf/util/debug.h:20:21: note: in definition of macro ‘pr_fmt’
>      20 | #define pr_fmt(fmt) fmt
>         |                     ^~~
>   tests/hwmon_pmu.c:200:25: note: in expansion of macro ‘pr_debug’
>     200 |                         pr_debug("FAILED %s:%d Unexpected config for '%s', %" PRIu64 " != %ld\n",
>         |                         ^~~~~~~~
>   cc1: all warnings being treated as errors
>
> So the way to satisfy both compilers is to also add a (u64) cast to
> arg7.

As the inttypes.h definitions match stdint.h would it make more sense
to use uint64_t for the cast?

Thanks,
Ian

> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> ---
>  tools/perf/tests/hwmon_pmu.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/tests/hwmon_pmu.c b/tools/perf/tests/hwmon_pmu.c
> index ada6e445c4c41e1b..870d59c0f7cba2e7 100644
> --- a/tools/perf/tests/hwmon_pmu.c
> +++ b/tools/perf/tests/hwmon_pmu.c
> @@ -2,6 +2,7 @@
>  #include "hwmon_pmu.h"
>
>  #include <errno.h>
> +#include <inttypes.h>
>
>  #include <fcntl.h>
>  #include <linux/compiler.h>
> @@ -196,9 +197,9 @@ static int do_test(size_t i, bool with_pmu, bool with_alias)
>                         continue;
>
>                 if (evsel->core.attr.config != (u64)test_events[i].key.type_and_num) {
> -                       pr_debug("FAILED %s:%d Unexpected config for '%s', %lld != %ld\n",
> +                       pr_debug("FAILED %s:%d Unexpected config for '%s', %" PRIu64 " != %ld\n",
>                                 __FILE__, __LINE__, str,
> -                               evsel->core.attr.config,
> +                               (u64)evsel->core.attr.config,
>                                 test_events[i].key.type_and_num);
>                         ret = TEST_FAIL;
>                         goto out;
> --
> 2.54.0
>