linux-kernel - Re: [PATCH V1 19/23] libperf evlist: Check nr

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Date:   Thu, 5 May 2022 17:13:14 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>,
        Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Leo Yan <leo.yan@...aro.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V1 19/23] libperf evlist: Check nr_mmaps is correct

On Thu, May 5, 2022 at 9:58 AM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> Print an error message if the predetermined number of mmaps is
> incorrect.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
>  tools/lib/perf/evlist.c                | 11 +++++++++--
>  tools/lib/perf/include/internal/mmap.h |  5 +++++
>  2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
> index 0acf43946479..8a82b4b94b99 100644
> --- a/tools/lib/perf/evlist.c
> +++ b/tools/lib/perf/evlist.c
> @@ -23,6 +23,7 @@
>  #include <perf/cpumap.h>
>  #include <perf/threadmap.h>
>  #include <api/fd/array.h>
> +#include "internal.h"
>
>  void perf_evlist__init(struct perf_evlist *evlist)
>  {
> @@ -424,7 +425,7 @@ static void perf_evlist__set_mmap_first(struct perf_evlist *evlist, struct perf_
>  static int
>  mmap_per_evsel(struct perf_evlist *evlist, struct perf_evlist_mmap_ops *ops,
>                int idx, struct perf_mmap_param *mp, int cpu_idx,
> -              int thread, int *_output, int *_output_overwrite)
> +              int thread, int *_output, int *_output_overwrite, int *nr_mmaps)
>  {
>         struct perf_cpu evlist_cpu = perf_cpu_map__cpu(evlist->all_cpus, cpu_idx);
>         struct perf_evsel *evsel;
> @@ -480,6 +481,8 @@ mmap_per_evsel(struct perf_evlist *evlist, struct perf_evlist_mmap_ops *ops,
>                         if (ops->mmap(map, mp, *output, evlist_cpu) < 0)
>                                 return -1;
>
> +                       *nr_mmaps += 1;
> +
>                         if (!idx)
>                                 perf_evlist__set_mmap_first(evlist, map, overwrite);
>                 } else {
> @@ -514,6 +517,7 @@ mmap_per_cpu(struct perf_evlist *evlist, struct perf_evlist_mmap_ops *ops,
>  {
>         int nr_threads = perf_thread_map__nr(evlist->threads);
>         int nr_cpus    = perf_cpu_map__nr(evlist->all_cpus);
> +       int nr_mmaps = 0;
>         int cpu, thread;
>
>         for (cpu = 0; cpu < nr_cpus; cpu++) {
> @@ -522,11 +526,14 @@ mmap_per_cpu(struct perf_evlist *evlist, struct perf_evlist_mmap_ops *ops,
>
>                 for (thread = 0; thread < nr_threads; thread++) {
>                         if (mmap_per_evsel(evlist, ops, cpu, mp, cpu,
> -                                          thread, &output, &output_overwrite))
> +                                          thread, &output, &output_overwrite, &nr_mmaps))
>                                 goto out_unmap;
>                 }
>         }
>
> +       if (nr_mmaps != evlist->nr_mmaps)
> +               pr_err("Miscounted nr_mmaps %d vs %d\n", nr_mmaps, evlist->nr_mmaps);
> +
>         return 0;
>
>  out_unmap:
> diff --git a/tools/lib/perf/include/internal/mmap.h b/tools/lib/perf/include/internal/mmap.h
> index 5a062af8e9d8..9b00828e70ef 100644
> --- a/tools/lib/perf/include/internal/mmap.h
> +++ b/tools/lib/perf/include/internal/mmap.h
> @@ -56,4 +56,9 @@ u64 perf_mmap__read_head(struct perf_mmap *map);
>
>  int perf_mmap__read_self(struct perf_mmap *map, struct perf_counts_values *count);
>
> +static inline bool perf_mmap__is_mmapped(struct perf_mmap *map)
> +{
> +       return map->base;
> +}
> +

This function is added here but not actually used by the patch.

Thanks,
Ian

>  #endif /* __LIBPERF_INTERNAL_MMAP_H */
> --
> 2.25.1
>