linux-kernel - Re: [PATCH] kconfig: fix missing choice values in auto.conf

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Message-ID: <CAK7LNASPib2GUgjUEwmNYcO9_NgvjyjKSpqwJVZSNhFOJ7Lkfw@mail.gmail.com>
Date:   Sat, 3 Aug 2019 11:32:33 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     "M. Vefa Bicakci" <m.v.b@...box.com>
Cc:     Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Joonas Kylmälä <joonas.kylmala@....fi>,
        Ulf Magnusson <ulfalizer@...il.com>,
        linux-stable <stable@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kconfig: fix missing choice values in auto.conf

On Sat, Aug 3, 2019 at 9:35 AM M. Vefa Bicakci <m.v.b@...box.com> wrote:
>
> Hello,
>
> > conf_write() must be changed accordingly. Currently, it clears
> > SYMBOL_WRITE after the symbol is written into the .config file. This
> > is needed to prevent it from writing the same symbol multiple times in
> > case the symbol is declared in two or more locations. I added the new
> > flag SYMBOL_WRITTEN, to track the symbols that have been written.
> [snip]
> > diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
> > index cbb6efa4a5a6..e0972b255aac 100644
> > --- a/scripts/kconfig/confdata.c
> > +++ b/scripts/kconfig/confdata.c
> [snip]
> > @@ -903,7 +904,7 @@ int conf_write(const char *name)
> >                               fprintf(out, "\n");
> >                               need_newline = false;
> >                       }
> > -                     sym->flags &= ~SYMBOL_WRITE;
> > +                     sym->flags |= SYMBOL_WRITTEN;
>
> The SYMBOL_WRITTEN flag is never cleared after being set in this
> function, which unfortunately causes data loss to occur when a user
> starts xconfig, gconfig, or nconfig and saves a config file more than
> once. Every save operation after the first one causes the saved .config
> file to contain only comments.
>
> I am appending a patch that resolves this issue. The patch is a bit
> ugly because of the code duplication, but it fixes this bug. (I have
> lightly tested the patch.) Even if the patch is not merged, I would
> appreciate it if this bug could be fixed.
>
> Thank you,




When you clear a flag, the tree traverse order is not a big deal.
So, you can use for_all_symbols() iterator.


Could you send v2 with the following code ?



       for_all_symbols(i, sym)
               sym->flags &= ~SYMBOL_WRITTEN;



This is quite simple, so you do not need to create a
new helper function for this.


Thanks.




>
> Vefa
>
> === 8< === Patch Follows === >8 ===
>
> From: "M. Vefa Bicakci" <m.v.b@...box.com>
> Date: Fri, 2 Aug 2019 17:44:40 -0400
> Subject: [PATCH] kconfig: Clear "written" flag to avoid data loss
>
> Prior to this commit, starting nconfig, xconfig or gconfig, and saving
> the .config file more than once caused data loss, where a .config file
> that contained only comments would be written to disk starting from the
> second save operation.
>
> This bug manifests itself because the SYMBOL_WRITTEN flag is never
> cleared after the first call to conf_write, and subsequent calls to
> conf_write then skip all of the configuration symbols due to the
> SYMBOL_WRITTEN flag being set.
>
> This commit resolves this issue by clearing the SYMBOL_WRITTEN flag
> from all symbols before conf_write returns.
>
> Fixes: 8e2442a5f86e ("kconfig: fix missing choice values in auto.conf")
> Cc: linux-stable <stable@...r.kernel.org> # 4.19+
> Signed-off-by: M. Vefa Bicakci <m.v.b@...box.com>
> ---
>  scripts/kconfig/confdata.c | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
>
> diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
> index 1134892599da..24fe0c851e8c 100644
> --- a/scripts/kconfig/confdata.c
> +++ b/scripts/kconfig/confdata.c
> @@ -840,6 +840,35 @@ int conf_write_defconfig(const char *filename)
>         return 0;
>  }
>
> +static void conf_clear_written_flag(void)
> +{
> +       struct menu *menu;
> +       struct symbol *sym;
> +
> +       menu = rootmenu.list;
> +       while (menu) {
> +               sym = menu->sym;
> +               if (sym && (sym->flags & SYMBOL_WRITTEN))
> +                       sym->flags &= ~SYMBOL_WRITTEN;
> +
> +               if (menu->list) {
> +                       menu = menu->list;
> +                       continue;
> +               }
> +
> +               if (menu->next) {
> +                       menu = menu->next;
> +               } else {
> +                       while ((menu = menu->parent)) {
> +                               if (menu->next) {
> +                                       menu = menu->next;
> +                                       break;
> +                               }
> +                       }
> +               }
> +       }
> +}
> +
>  int conf_write(const char *name)
>  {
>         FILE *out;
> @@ -930,6 +959,8 @@ int conf_write(const char *name)
>         }
>         fclose(out);
>
> +       conf_clear_written_flag();
> +
>         if (*tmpname) {
>                 if (is_same(name, tmpname)) {
>                         conf_message("No change to %s", name);
> --
> 2.21.0
>


-- 
Best Regards
Masahiro Yamada