Re: [PATCH] bpf: Fix undeclared function 'barrier_nospec' warning

[Alexei Starovoitov]

On Wed, Feb 22, 2023 at 7:33 AM Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
>
> On 2/22/23 07:03, Geert Uytterhoeven wrote:
> > On Wed, Feb 22, 2023 at 9:26 AM Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
> >> Add the missing header for architectures that don't define
> >> the barrier_nospec() macro. The nospec.h header is added after the
> >> inclusion of barrier.h to avoid redefining the macro for architectures
> >> that already define barrier_nospec() in their respective barrier.h
> >> headers.
> >>
> >> Fixes: 74e19ef0ff80 ("uaccess: Add speculation barrier to copy_from_user()")
> >> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> >> ---
> >> Linus's master branch fails currently to build for arm64 without this commit.
> > Not just arm64 🙁
> > http://kisskb.ellerman.id.au/kisskb/head/5b7c4cabbb65f5c469464da6c5f614cbd7f730f2
>
> Thanks for the fix, and sorry for the breakage, folks!  Obviously:
>
> Tested-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
>
> Now time to go make sure I have bpf turned on in all my cross builds.

Not clear why the broken commit got applied bypassing bpf@vger and not
going through BPF CI. :(

Yesterday I applied pretty much the same fix from Huacai Chen.

https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=345d24a91c79f408e355c8b7e873ccde0f097eea

and BPF CI is now back to green.

Linus,
Since the blast radius is big, may be apply the fix directly ?