Re: linux-next: build failure after merge of the net-next tree

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Kalle,

On Fri, Oct 8, 2021 at 7:55 AM Kalle Valo <kvalo@codeaurora.org> wrote:
> Stephen Rothwell <sfr@canb.auug.org.au> writes:
>
> > After merging the net-next tree, today's linux-next build (xtensa,
> > m68k allmodconfig) failed like this:
> >
> > In file included from <command-line>:0:0:
> > In function 'ath11k_peer_assoc_h_smps',
> >     inlined from 'ath11k_peer_assoc_prepare' at drivers/net/wireless/ath/ath11k/mac.c:2362:2:
> > include/linux/compiler_types.h:317:38: error: call to '__compiletime_assert_650' declared with attribute error: FIELD_GET: type of reg too small for mask
> >   _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> >                                       ^
> > include/linux/compiler_types.h:298:4: note: in definition of macro '__compiletime_assert'
> >     prefix ## suffix();    \
> >     ^
> > include/linux/compiler_types.h:317:2: note: in expansion of macro '_compiletime_assert'
> >   _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> >   ^
> > include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert'
> >  #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
> >                                      ^
> > include/linux/bitfield.h:52:3: note: in expansion of macro 'BUILD_BUG_ON_MSG'
> >    BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ull,  \
> >    ^
> > include/linux/bitfield.h:108:3: note: in expansion of macro '__BF_FIELD_CHECK'
> >    __BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: "); \
> >    ^
> > drivers/net/wireless/ath/ath11k/mac.c:2079:10: note: in expansion of macro 'FIELD_GET'
> >    smps = FIELD_GET(IEEE80211_HE_6GHZ_CAP_SM_PS,
> >           ^
> >
> > Caused by commit
> >
> >   6f4d70308e5e ("ath11k: support SMPS configuration for 6 GHz")
>
> Thanks for the report, weird that I don't see it on x86. I can't look at
> this in detail now, maybe later today, but I wonder if the diff below
> fixes the issue?

It seems to be related to passing "le16_to_cpu(sta->he_6ghz_capa.capa)".
Probably typeof(le16_to_cpu(sta->he_6ghz_capa.capa)) goes berserk.
le16_to_cpu() is a complex macro on big-endian. I had expected to see
a similar issue on powerpc, but I don't.
Using an intermediate "u16 capa = le16_to_cpu(sta->he_6ghz_capa.capa)"
fixes the problem.

> At least it's cleaner than using FIELD_GET(), actually ath11k should be
> cleaned up to use xx_get_bits() all over.
>
> Kalle
>
> diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
> index d897020dd52d..3e7e569f284b 100644
> --- a/drivers/net/wireless/ath/ath11k/mac.c
> +++ b/drivers/net/wireless/ath/ath11k/mac.c
> @@ -2076,8 +2076,8 @@ static void ath11k_peer_assoc_h_smps(struct ieee80211_sta *sta,
>                 smps = ht_cap->cap & IEEE80211_HT_CAP_SM_PS;
>                 smps >>= IEEE80211_HT_CAP_SM_PS_SHIFT;
>         } else {
> -               smps = FIELD_GET(IEEE80211_HE_6GHZ_CAP_SM_PS,
> -                                le16_to_cpu(sta->he_6ghz_capa.capa));
> +               smps = le16_get_bits(sta->he_6ghz_capa.capa,
> +                                    IEEE80211_HE_6GHZ_CAP_SM_PS);
>         }

Thanks, that works, too, so (compile)
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>

Gr{oetje,eeting}s,

                        Geert


--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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