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SubjectRe: [PATCH] perf kcore_copy: Do not check /proc/modules is unchanged
Em Fri, Sep 16, 2022 at 11:02:25AM -0700, Namhyung Kim escreveu:
> On Wed, Sep 14, 2022 at 5:24 AM Adrian Hunter <adrian.hunter@intel.com> wrote:
> >
> > /proc/kallsyms and /proc/modules are compared before and after the copy
> > in order to ensure no changes during the copy. However /proc/modules
> > also might change due to reference counts changing even though that
> > does not make any difference. Any modules loaded or unloaded should be
> > visible in changes to kallsyms, so it is not necessary to check
> > /proc/modules also anyway.
> >
> > Remove the comparison checking that /proc/modules is unchanged.
> >
> > Reported-by: Daniel Dao <dqminh@cloudflare.com>
> > Fixes: fc1b691d7651 ("perf buildid-cache: Add ability to add kcore to the cache")
> > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
>
> Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks, applied.

- Arnaldo


> Thanks,
> Namhyung
>
>
> > ---
> > tools/perf/util/symbol-elf.c | 7 ++-----
> > 1 file changed, 2 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> > index 75bec32d4f57..647b7dff8ef3 100644
> > --- a/tools/perf/util/symbol-elf.c
> > +++ b/tools/perf/util/symbol-elf.c
> > @@ -2102,8 +2102,8 @@ static int kcore_copy__compare_file(const char *from_dir, const char *to_dir,
> > * unusual. One significant peculiarity is that the mapping (start -> pgoff)
> > * is not the same for the kernel map and the modules map. That happens because
> > * the data is copied adjacently whereas the original kcore has gaps. Finally,
> > - * kallsyms and modules files are compared with their copies to check that
> > - * modules have not been loaded or unloaded while the copies were taking place.
> > + * kallsyms file is compared with its copy to check that modules have not been
> > + * loaded or unloaded while the copies were taking place.
> > *
> > * Return: %0 on success, %-1 on failure.
> > */
> > @@ -2166,9 +2166,6 @@ int kcore_copy(const char *from_dir, const char *to_dir)
> > goto out_extract_close;
> > }
> >
> > - if (kcore_copy__compare_file(from_dir, to_dir, "modules"))
> > - goto out_extract_close;
> > -
> > if (kcore_copy__compare_file(from_dir, to_dir, "kallsyms"))
> > goto out_extract_close;
> >
> > --
> > 2.25.1
> >

--

- Arnaldo

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