linux-kernel - Re: [PATCH 1/3] perf jvmti: Fix jitdump for methods without debug info

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Message-ID: <CAP-5=fUJt6bN4egoQ7ohWTPN40YCyf+819iSvH_noggnOHaoKA@mail.gmail.com>
Date:   Thu, 14 May 2020 15:06:59 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Nick Gasson <nick.gasson@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] perf jvmti: Fix jitdump for methods without debug info

On Sun, Apr 26, 2020 at 11:16 PM Nick Gasson <nick.gasson@....com> wrote:
>
> If a Java class is compiled with -g:none to omit debug information, the
> JVMTI plugin won't write jitdump entries for any method in this class
> and prints a lot of errors like:
>
>     java: GetSourceFileName failed with JVMTI_ERROR_ABSENT_INFORMATION
>
> The call to GetSourceFileName is used to derive the file name `fn`, but
> this value is not actually used since commit ca58d7e64bdf ("perf jvmti:
> Generate correct debug information for inlined code") which moved the
> file name lookup into fill_source_filenames(). So the call to
> GetSourceFileName and related code can be safely removed.
>
> Signed-off-by: Nick Gasson <nick.gasson@....com>

Reviewed-by: Ian Rogers <irogers@...gle.com>
Tested-by: Ian Rogers <irogers@...gle.com>

Thanks!
Ian

> ---
>  tools/perf/jvmti/libjvmti.c | 11 -----------
>  1 file changed, 11 deletions(-)
>
> diff --git a/tools/perf/jvmti/libjvmti.c b/tools/perf/jvmti/libjvmti.c
> index c441a34cb1c0..50ef524b5cd4 100644
> --- a/tools/perf/jvmti/libjvmti.c
> +++ b/tools/perf/jvmti/libjvmti.c
> @@ -246,8 +246,6 @@ compiled_method_load_cb(jvmtiEnv *jvmti,
>         char *class_sign = NULL;
>         char *func_name = NULL;
>         char *func_sign = NULL;
> -       char *file_name = NULL;
> -       char fn[PATH_MAX];
>         uint64_t addr = (uint64_t)(uintptr_t)code_addr;
>         jvmtiError ret;
>         int nr_lines = 0; /* in line_tab[] */
> @@ -282,12 +280,6 @@ compiled_method_load_cb(jvmtiEnv *jvmti,
>                 }
>         }
>
> -       ret = (*jvmti)->GetSourceFileName(jvmti, decl_class, &file_name);
> -       if (ret != JVMTI_ERROR_NONE) {
> -               print_error(jvmti, "GetSourceFileName", ret);
> -               goto error;
> -       }
> -
>         ret = (*jvmti)->GetClassSignature(jvmti, decl_class,
>                                           &class_sign, NULL);
>         if (ret != JVMTI_ERROR_NONE) {
> @@ -302,8 +294,6 @@ compiled_method_load_cb(jvmtiEnv *jvmti,
>                 goto error;
>         }
>
> -       copy_class_filename(class_sign, file_name, fn, PATH_MAX);
> -
>         /*
>          * write source line info record if we have it
>          */
> @@ -323,7 +313,6 @@ compiled_method_load_cb(jvmtiEnv *jvmti,
>         (*jvmti)->Deallocate(jvmti, (unsigned char *)func_name);
>         (*jvmti)->Deallocate(jvmti, (unsigned char *)func_sign);
>         (*jvmti)->Deallocate(jvmti, (unsigned char *)class_sign);
> -       (*jvmti)->Deallocate(jvmti, (unsigned char *)file_name);
>         free(line_tab);
>         while (line_file_names && (nr_lines > 0)) {
>             if (line_file_names[nr_lines - 1]) {
> --
> 2.26.1
>