linux-kernel - Re: [PATCH] modpost: use strstarts() to clean up parse_source

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Message-ID: <Z6r9g9cYk_mWsRBo@fjasle.eu>
Date: Tue, 11 Feb 2025 08:34:27 +0100
From: Nicolas Schier <nicolas@...sle.eu>
To: Masahiro Yamada <masahiroy@...nel.org>
Cc: linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
 Nathan Chancellor <nathan@...nel.org>
Subject: Re: [PATCH] modpost: use strstarts() to clean up parse_source_files()

On Tue, Feb 11, 2025 at 09:43:05AM +0900 Masahiro Yamada wrote:
> On Sat, Feb 8, 2025 at 6:38 PM Nicolas Schier <nicolas@...sle.eu> wrote:
> >
> > On Sat 08 Feb 2025 02:50:55 GMT, Masahiro Yamada wrote:
> > > No functional changes are intended.
> > >
> > > Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> > > ---
> > >
> > >  scripts/mod/sumversion.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/scripts/mod/sumversion.c b/scripts/mod/sumversion.c
> > > index e79fc40d852f..3dd28b4d0099 100644
> > > --- a/scripts/mod/sumversion.c
> > > +++ b/scripts/mod/sumversion.c
> > > @@ -330,7 +330,7 @@ static int parse_source_files(const char *objfile, struct md4_ctx *md)
> > >                       line++;
> > >               p = line;
> > >
> > > -             if (strncmp(line, "source_", sizeof("source_")-1) == 0) {
> > > +             if (strstarts(line, "source_")) {
> > >                       p = strrchr(line, ' ');
> > >                       if (!p) {
> > >                               warn("malformed line: %s\n", line);
> > > @@ -344,7 +344,7 @@ static int parse_source_files(const char *objfile, struct md4_ctx *md)
> > >                       }
> > >                       continue;
> > >               }
> > > -             if (strncmp(line, "deps_", sizeof("deps_")-1) == 0) {
> > > +             if (strstarts(line, "deps_")) {
> > >                       check_files = 1;
> > >                       continue;
> > >               }
> > > --
> > > 2.43.0
> > >
> >
> > Thanks, looks good to me.
> >
> > Reviewed-by: Nicolas Schier <nicolas@...sle.eu>
> >
> > Do you also want to replace the last strncmp() in
> > scripts/mod/modpost.c?
> >
> > diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> > index e18ae7dc8140..31468923cdf6 100644
> > --- a/scripts/mod/modpost.c
> > +++ b/scripts/mod/modpost.c
> > @@ -670,7 +670,7 @@ static char *get_next_modinfo(struct elf_info *info, const char *tag,
> >         }
> >
> >         for (p = modinfo; p; p = next_string(p, &size)) {
> > -               if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=')
> > +               if (strstarts(p, tag) == 0 && p[taglen] == '=')
> >                         return p + taglen + 1;
> >         }
> >         return NULL;
> 
> 
> I believe you meant:
> 
>   if (strstarts(p, tag) && p[taglen] == '=')

ups, yes.

> I do not think there is a strong reason to do so
> because taglen is already calculated a few lines above,
> but the compiler may be clever enough to avoid
> calling strlen() twice. I did not check the compiler output.

yeah,  I was thinking about code (style) consistency, but you're right, it
would not be beneficial.

Kind regards,
Nicolas