Re: [PATCH] lib: add missing files from libfdt

["AKASHI, Takahiro" <takahiro.akashi@linaro.org>]

Rob,

On Fri, Sep 28, 2018 at 07:49:13AM -0500, Rob Herring wrote:
> On Wed, Sep 26, 2018 at 12:57 AM AKASHI Takahiro
> <takahiro.akashi@linaro.org> wrote:
> >
> > There are two files that are part of dtc/libfdt, but don't appear
> > in lib. This patch fixes it.
> > Please note that strtoul() used in fdt_overlay.c is now faked using
> > kstrtoul() (not simple_strtoul() which is obsolute).
> >
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> > Cc: Rob Herring <robh+dt@kernel.org>
> > Cc: Frank Rowand <frowand.list@gmail.com>
> > ---
> >  lib/Makefile        |  2 +-
> >  lib/fdt_addresses.c |  3 +++
> >  lib/fdt_overlay.c   | 23 +++++++++++++++++++++++
> >  3 files changed, 27 insertions(+), 1 deletion(-)
> >  create mode 100644 lib/fdt_addresses.c
> >  create mode 100644 lib/fdt_overlay.c
> >
> > diff --git a/lib/Makefile b/lib/Makefile
> > index ca3f7ebb900d..444c82413a3c 100644
> > --- a/lib/Makefile
> > +++ b/lib/Makefile
> > @@ -202,7 +202,7 @@ KASAN_SANITIZE_stackdepot.o := n
> >  KCOV_INSTRUMENT_stackdepot.o := n
> >
> >  libfdt_files = fdt.o fdt_ro.o fdt_wip.o fdt_rw.o fdt_sw.o fdt_strerror.o \
> > -              fdt_empty_tree.o
> > +              fdt_empty_tree.o fdt_addresses.o fdt_overlay.o
> 
> Nothing in the kernel needs fdt_overlay.o, so we shouldn't add it
> until we do. It used to bloat the kernel size, but maybe that changed
> with using archive files now.
> 
> >  $(foreach file, $(libfdt_files), \
> >         $(eval CFLAGS_$(file) = -I$(src)/../scripts/dtc/libfdt))
> >  lib-$(CONFIG_LIBFDT) += $(libfdt_files)
> > diff --git a/lib/fdt_addresses.c b/lib/fdt_addresses.c
> > new file mode 100644
> > index 000000000000..241780d09882
> > --- /dev/null
> > +++ b/lib/fdt_addresses.c
> > @@ -0,0 +1,3 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +#include <linux/libfdt_env.h>
> > +#include "../scripts/dtc/libfdt/fdt_addresses.c"
> > diff --git a/lib/fdt_overlay.c b/lib/fdt_overlay.c
> > new file mode 100644
> > index 000000000000..1def7268d313
> > --- /dev/null
> > +++ b/lib/fdt_overlay.c
> > @@ -0,0 +1,23 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +#include <linux/kernel.h>
> > +#include <linux/libfdt_env.h>
> > +
> > +static unsigned long strtoul(const char *nptr, char **endptr, int base)
> > +{
> > +       unsigned long res;
> > +       int ret;
> > +
> > +       /*
> > +        * FIXME: no way to return a correct value of endptr.
> > +        * The values here would be still good for use in fdt_overlay
> > +        */
> > +       *endptr = (char *)nptr;
> 
> endptr could be NULL.

No, it couldn't at overlay_fixup_phandle(), which is the only caller
of strtoul() in fdt_overlay.c, is concerned.

> > +       ret = kstrtoul(nptr, base, &res);
> 
> kstrtoul doesn't handle conversions if there are non-convertible
> characters after the number while strtoul (including simple_strtoul)
> will still do the conversion.

I don't believe so.

> We should make sure we don't need that
> behavior. That's doubtful if callers pass non-NULL endptr.
> 
> > +       if (ret < 0)
> > +               return ULONG_MAX;
> > +
> > +       (*endptr)++;
> > +       return res;
> > +}
> > +
> > +#include "../scripts/dtc/libfdt/fdt_overlay.c"
> > --
> > 2.18.0
> >

Having said that, I would simply drop 'fdt_overlay' part from my patch
as it won't be used anywhere at this stage.
Are you happy with this change?

Thanks,
-Takahiro Akashi