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From:   Ian Rogers <irogers@google.com>
Date:   Tue, 25 May 2021 16:25:48 -0700
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Subject: Re: [PATCH] perf test: iterate over shell tests in alphabetical order
To:     Riccardo Mancini <rickyman7@gmail.com>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>, Leo Yan <leo.yan@linaro.org>,
        Fabian Hemmer <copy@copy.sh>,
        Tommi Rantala <tommi.t.rantala@nokia.com>,
        Stephane Eranian <eranian@google.com>,
        linux-perf-users <linux-perf-users@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Tue, May 25, 2021 at 4:08 PM Riccardo Mancini <rickyman7@gmail.com> wrote:
>
> for_each_shell_test macro iterated over all shell tests in the directory
> using readdir, which does not guarantee any ordering, causing
> problems on certain fs. However, the order in which they are visited
> determines the id of the test, in case one wants to run a single test.
>
> This patch replaces readdir with scandir using alphabetical sorting.
> This guarantees that, given the same set of tests, all machines will
> see the tests in the same order, and, thus, that test ids are
> consistent.
>
> Signed-off-by: Riccardo Mancini <rickyman7@gmail.com>
> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Ian Rogers <irogers@google.com>

Acked-by: Ian Rogers <irogers@google.com>

> ---
>  tools/perf/tests/builtin-test.c | 38 ++++++++++++++++++---------------
>  1 file changed, 21 insertions(+), 17 deletions(-)
>
> diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
> index c4b888f18e9ca..cbbfe48ab8029 100644
> --- a/tools/perf/tests/builtin-test.c
> +++ b/tools/perf/tests/builtin-test.c
> @@ -510,8 +510,8 @@ static const char *shell_test__description(char *description, size_t size,
>         return description ? strim(description + 1) : NULL;
>  }
>
> -#define for_each_shell_test(dir, base, ent)    \
> -       while ((ent = readdir(dir)) != NULL)    \
> +#define for_each_shell_test(entlist, nr, base, ent)                    \
> +       for (int __i = 0; __i < nr && (ent = entlist[__i]); __i++)      \

I think this declaration of __i is okay as C99 allows declarations
here, but generally I don't see this style in the kernel.

Thanks,
Ian

>                 if (!is_directory(base, ent) && ent->d_name[0] != '.')
>
>  static const char *shell_tests__dir(char *path, size_t size)
> @@ -538,8 +538,9 @@ static const char *shell_tests__dir(char *path, size_t size)
>
>  static int shell_tests__max_desc_width(void)
>  {
> -       DIR *dir;
> +       struct dirent **entlist;
>         struct dirent *ent;
> +       int n_dirs;
>         char path_dir[PATH_MAX];
>         const char *path = shell_tests__dir(path_dir, sizeof(path_dir));
>         int width = 0;
> @@ -547,11 +548,11 @@ static int shell_tests__max_desc_width(void)
>         if (path == NULL)
>                 return -1;
>
> -       dir = opendir(path);
> -       if (!dir)
> +       n_dirs = scandir(path, &entlist, NULL, alphasort);
> +       if (n_dirs == -1)
>                 return -1;
>
> -       for_each_shell_test(dir, path, ent) {
> +       for_each_shell_test(entlist, n_dirs, path, ent) {
>                 char bf[256];
>                 const char *desc = shell_test__description(bf, sizeof(bf), path, ent->d_name);
>
> @@ -563,7 +564,8 @@ static int shell_tests__max_desc_width(void)
>                 }
>         }
>
> -       closedir(dir);
> +       free(entlist);
> +
>         return width;
>  }
>
> @@ -589,8 +591,9 @@ static int shell_test__run(struct test *test, int subdir __maybe_unused)
>
>  static int run_shell_tests(int argc, const char *argv[], int i, int width)
>  {
> -       DIR *dir;
> +       struct dirent **entlist;
>         struct dirent *ent;
> +       int n_dirs;
>         char path_dir[PATH_MAX];
>         struct shell_test st = {
>                 .dir = shell_tests__dir(path_dir, sizeof(path_dir)),
> @@ -599,14 +602,14 @@ static int run_shell_tests(int argc, const char *argv[], int i, int width)
>         if (st.dir == NULL)
>                 return -1;
>
> -       dir = opendir(st.dir);
> -       if (!dir) {
> +       n_dirs = scandir(st.dir, &entlist, NULL, alphasort);
> +       if (n_dirs == -1) {
>                 pr_err("failed to open shell test directory: %s\n",
>                         st.dir);
>                 return -1;
>         }
>
> -       for_each_shell_test(dir, st.dir, ent) {
> +       for_each_shell_test(entlist, n_dirs, st.dir, ent) {
>                 int curr = i++;
>                 char desc[256];
>                 struct test test = {
> @@ -623,7 +626,7 @@ static int run_shell_tests(int argc, const char *argv[], int i, int width)
>                 test_and_print(&test, false, -1);
>         }
>
> -       closedir(dir);
> +       free(entlist);
>         return 0;
>  }
>
> @@ -722,19 +725,20 @@ static int __cmd_test(int argc, const char *argv[], struct intlist *skiplist)
>
>  static int perf_test__list_shell(int argc, const char **argv, int i)
>  {
> -       DIR *dir;
> +       struct dirent **entlist;
>         struct dirent *ent;
> +       int n_dirs;
>         char path_dir[PATH_MAX];
>         const char *path = shell_tests__dir(path_dir, sizeof(path_dir));
>
>         if (path == NULL)
>                 return -1;
>
> -       dir = opendir(path);
> -       if (!dir)
> +       n_dirs = scandir(path, &entlist, NULL, alphasort);
> +       if (n_dirs == -1)
>                 return -1;
>
> -       for_each_shell_test(dir, path, ent) {
> +       for_each_shell_test(entlist, n_dirs, path, ent) {
>                 int curr = i++;
>                 char bf[256];
>                 struct test t = {
> @@ -747,7 +751,7 @@ static int perf_test__list_shell(int argc, const char **argv, int i)
>                 pr_info("%2d: %s\n", i, t.desc);
>         }
>
> -       closedir(dir);
> +       free(entlist);
>         return 0;
>  }
>
> --
> 2.31.1
>