linux-kernel - Re: linux-next: Tree for Nov 17 (uml, no IPV6)

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Date:   Wed, 17 Nov 2021 01:38:27 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Randy Dunlap <rdunlap@...radead.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Netdev <netdev@...r.kernel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Subject: Re: linux-next: Tree for Nov 17 (uml, no IPV6)

On Wed, Nov 17, 2021 at 12:44 AM Geert Uytterhoeven
<geert@...ux-m68k.org> wrote:
>
> Hi Randy,
>
> On Wed, Nov 17, 2021 at 6:49 AM Randy Dunlap <rdunlap@...radead.org> wrote:
> > On 11/16/21 6:58 PM, Stephen Rothwell wrote:
> > > Changes since 20211116:
> >
> > ARCH=um SUBARCH=x86_64:
> > # CONFIG_IPV6 is not set
>
> It doesn't always happen with CONFIG_IPV6=n, so I guess that's why
> it wasn't detected before.

Thanks for letting me know

I guess the following addition would fix the issue ?

diff --git a/arch/x86/um/asm/checksum_64.h b/arch/x86/um/asm/checksum_64.h
index 7b6cd1921573c97361b8d486bbba3e8870d53ad6..4f0c15a61925c46b261f87fa319e6aff28f4cfce
100644
--- a/arch/x86/um/asm/checksum_64.h
+++ b/arch/x86/um/asm/checksum_64.h
@@ -14,6 +14,30 @@ static inline unsigned add32_with_carry(unsigned a,
unsigned b)
         return a;
 }

+#define _HAVE_ARCH_IPV6_CSUM
+static inline __sum16
+csum_ipv6_magic(const struct in6_addr *saddr,
+               const struct in6_addr *daddr,
+               __u32 len, __u8 proto, __wsum sum)
+{
+       __u64 rest, sum64;
+
+       rest = (__force __u64)htonl(len) + (__force __u64)htons(proto) +
+               (__force __u64)sum;
+
+       asm("   addq (%[saddr]),%[sum]\n"
+           "   adcq 8(%[saddr]),%[sum]\n"
+           "   adcq (%[daddr]),%[sum]\n"
+           "   adcq 8(%[daddr]),%[sum]\n"
+           "   adcq $0,%[sum]\n"
+
+           : [sum] "=r" (sum64)
+           : "[sum]" (rest), [saddr] "r" (saddr), [daddr] "r" (daddr));
+
+       return csum_fold(
+              (__force __wsum)add32_with_carry(sum64 & 0xffffffff, sum64>>32));
+}
+
 extern __sum16 ip_compute_csum(const void *buff, int len);

 #endif


>
> > In file included from ../net/ethernet/eth.c:62:0:
> > ../include/net/gro.h: In function ‘ip6_gro_compute_pseudo’:
> > ../include/net/gro.h:413:22: error: implicit declaration of function ‘csum_ipv6_magic’; did you mean ‘csum_tcpudp_magic’? [-Werror=implicit-function-declaration]
> >    return ~csum_unfold(csum_ipv6_magic(&iph->saddr, &iph->daddr,
> >                        ^~~~~~~~~~~~~~~
> >                        csum_tcpudp_magic
> >
> >
> > After I made ip6_gro_compute_pseudo() conditional on CONFIG_IPV6,
> > I got this build error:
> >
> > In file included from ../net/ipv6/tcpv6_offload.c:10:0:
> > ../net/ipv6/tcpv6_offload.c: In function ‘tcp6_gro_receive’:
> > ../net/ipv6/tcpv6_offload.c:22:11: error: implicit declaration of function ‘ip6_gro_compute_pseudo’; did you mean ‘inet_gro_compute_pseudo’? [-Werror=implicit-function-declaration]
> >             ip6_gro_compute_pseudo)) {
> >             ^
> > ../include/net/gro.h:235:5: note: in definition of macro ‘__skb_gro_checksum_validate’
> >       compute_pseudo(skb, proto));  \
> >       ^~~~~~~~~~~~~~
> > ../net/ipv6/tcpv6_offload.c:21:6: note: in expansion of macro ‘skb_gro_checksum_validate’
> >        skb_gro_checksum_validate(skb, IPPROTO_TCP,
> >        ^~~~~~~~~~~~~~~~~~~~~~~~~
> >
> >
> >
> > This is UML x86_64 defconfig:
> >
> > $ make ARCH=um SUBARCH=x86_64 defconfig all
>
> noreply@...erman.id.au reported the same issue for m5272c3_defconfig,
> and I've bisected the failure to commit 4721031c3559db8e ("net:
> move gro definitions to include/net/gro.h").
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds