New linux-next KCFLAGS

[Kees Cook]

On Sun, Nov 25, 2018 at 1:48 PM Stephen Rothwell <sfr at canb.auug.org.au> wrote:
>
> Hi Kees,
>
> On Fri, 26 Oct 2018 01:34:33 +0100 Kees Cook <keescook at google.com> wrote:
> >
> > So, if you it's possible to "seed" some new flags for linux-next, I'd
> > be interested in making sure no new instances of warnings from
> > -Wimplicit-fallthrough (gcc 7.1 and later) appear. VLAs will be gone
> > in a couple days, so I'm currently only interested in killing implicit
> > fallthroughs[1] now. There are hundreds of cases remaining, so ignore
> > those on the first build, but anything NEW is what I'd like to get
> > maintainer nags sent for (CCing myself and Gustavo Silva would be
> > especially nice, too).
>
> I don't know Gustavo's email address ...
>
> > Thanks!
> >
> > [1] Gustavo has fixed lots of actual bugs as part of this work:
> >      https://lkml.kernel.org/r/1f64449a-ef19-20c8-f8cb-7e629f8fe71b@embeddedor.com
>
> I finally got around to this.  I have added the following patch to my
> fixes tree (which is merged immediately after Linus' tree).

Excellent! (Though, wait, does this mean everyone _else_ will see this
too? I'm worried that will be way too noisy...)

> FYI, I am currently ignoring 659 such warnings in Linus' tree ...

That sound about right. Before Gustavo started there maybe 1000 more. (!) :)

Thanks!

-Kees

> commit 4d8360ade996cf1823e570544791c9d7bd660ffb
> Author: Stephen Rothwell <sfr at canb.auug.org.au>
> Date:   Mon Nov 26 07:58:34 2018 +1100
>
>     Check for new cases of implict fallthrough
>
>     for Kees
>
>     Signed-off-by: Stephen Rothwell <sfr at canb.auug.org.au>
>
> diff --git a/Makefile b/Makefile
> index ddbf627cad8f..380164f590bc 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -804,6 +804,9 @@ KBUILD_CFLAGS += -Wdeclaration-after-statement
>  # Variable Length Arrays (VLAs) should not be used anywhere in the kernel
>  KBUILD_CFLAGS += $(call cc-option,-Wvla)
>
> +# Check for implict fallthroughs
> +KBUILD_CFLAGS += $(call cc-option,-Wimplicit-fallthrough)
> +
>  # disable pointer signed / unsigned warnings in gcc 4.0
>  KBUILD_CFLAGS += -Wno-pointer-sign
>
>
> Unfortunately, some of the kernel is built with -Werror, so I have had
> to add the following patch as well just to build Linus' tree:
>
> (I just marked them as "fall through", I am not sure if that is the
> correct resolution.)
>
> From: Stephen Rothwell <sfr at canb.auug.org.au>
> Date: Mon, 26 Nov 2018 08:32:39 +1100
> Subject: [PATCH] powerpc: tag implicit fall throughs
>
> Signed-off-by: Stephen Rothwell <sfr at canb.auug.org.au>
> ---
>  arch/powerpc/kernel/nvram_64.c            | 1 +
>  arch/powerpc/platforms/powermac/feature.c | 1 +
>  arch/powerpc/xmon/xmon.c                  | 1 +
>  3 files changed, 3 insertions(+)
>
> diff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c
> index 22e9d281324d..06e2eda2430e 100644
> --- a/arch/powerpc/kernel/nvram_64.c
> +++ b/arch/powerpc/kernel/nvram_64.c
> @@ -809,6 +809,7 @@ static long dev_nvram_ioctl(struct file *file, unsigned int cmd,
>  #ifdef CONFIG_PPC_PMAC
>         case OBSOLETE_PMAC_NVRAM_GET_OFFSET:
>                 printk(KERN_WARNING "nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n");
> +               /* fall through */
>         case IOC_NVRAM_GET_OFFSET: {
>                 int part, offset;
>
> diff --git a/arch/powerpc/platforms/powermac/feature.c b/arch/powerpc/platforms/powermac/feature.c
> index ed2f54b3f173..a7ec06876b53 100644
> --- a/arch/powerpc/platforms/powermac/feature.c
> +++ b/arch/powerpc/platforms/powermac/feature.c
> @@ -1471,6 +1471,7 @@ static long g5_i2s_enable(struct device_node *node, long param, long value)
>         case 2:
>                 if (macio->type == macio_shasta)
>                         break;
> +               /* fall through */
>         default:
>                 return -ENODEV;
>         }
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index 36b8dc47a3c3..308326f8b7ed 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -4033,6 +4033,7 @@ static int do_spu_cmd(void)
>                 subcmd = inchar();
>                 if (isxdigit(subcmd) || subcmd == '\n')
>                         termch = subcmd;
> +               /* fall through */
>         case 'f':
>                 scanhex(&num);
>                 if (num >= XMON_NUM_SPUS || !spu_info[num].spu) {
> --
> 2.19.1
>
> --
> Cheers,
> Stephen Rothwell



-- 
Kees Cook