[PATCH v3] powerpc: fix EDEADLOCK redefinition error in uapi/asm/errno.h

[Tony Ambardar]

Hello Michael,

The latest version of this patch addressed all feedback I'm aware of
when submitted last September, and I've seen no further comments from
reviewers since then.

Could you please let me know where this stands and if anything further
is needed?

Kind regards,
Tony

On Thu, 17 Sept 2020 at 06:54, Tony Ambardar <tony.ambardar at gmail.com> wrote:
>
> A few archs like powerpc have different errno.h values for macros
> EDEADLOCK and EDEADLK. In code including both libc and linux versions of
> errno.h, this can result in multiple definitions of EDEADLOCK in the
> include chain. Definitions to the same value (e.g. seen with mips) do
> not raise warnings, but on powerpc there are redefinitions changing the
> value, which raise warnings and errors (if using "-Werror").
>
> Guard against these redefinitions to avoid build errors like the following,
> first seen cross-compiling libbpf v5.8.9 for powerpc using GCC 8.4.0 with
> musl 1.1.24:
>
>   In file included from ../../arch/powerpc/include/uapi/asm/errno.h:5,
>                    from ../../include/linux/err.h:8,
>                    from libbpf.c:29:
>   ../../include/uapi/asm-generic/errno.h:40: error: "EDEADLOCK" redefined [-Werror]
>    #define EDEADLOCK EDEADLK
>
>   In file included from toolchain-powerpc_8540_gcc-8.4.0_musl/include/errno.h:10,
>                    from libbpf.c:26:
>   toolchain-powerpc_8540_gcc-8.4.0_musl/include/bits/errno.h:58: note: this is the location of the previous definition
>    #define EDEADLOCK       58
>
>   cc1: all warnings being treated as errors
>
> CC: Stable <stable at vger.kernel.org>
> Reported-by: Rosen Penev <rosenp at gmail.com>
> Signed-off-by: Tony Ambardar <Tony.Ambardar at gmail.com>
> ---
> v1 -> v2:
>  * clean up commit description formatting
>
> v2 -> v3: (per Michael Ellerman)
>  * drop indeterminate 'Fixes' tags, request stable backports instead
> ---
>  arch/powerpc/include/uapi/asm/errno.h       | 1 +
>  tools/arch/powerpc/include/uapi/asm/errno.h | 1 +
>  2 files changed, 2 insertions(+)
>
> diff --git a/arch/powerpc/include/uapi/asm/errno.h b/arch/powerpc/include/uapi/asm/errno.h
> index cc79856896a1..4ba87de32be0 100644
> --- a/arch/powerpc/include/uapi/asm/errno.h
> +++ b/arch/powerpc/include/uapi/asm/errno.h
> @@ -2,6 +2,7 @@
>  #ifndef _ASM_POWERPC_ERRNO_H
>  #define _ASM_POWERPC_ERRNO_H
>
> +#undef EDEADLOCK
>  #include <asm-generic/errno.h>
>
>  #undef EDEADLOCK
> diff --git a/tools/arch/powerpc/include/uapi/asm/errno.h b/tools/arch/powerpc/include/uapi/asm/errno.h
> index cc79856896a1..4ba87de32be0 100644
> --- a/tools/arch/powerpc/include/uapi/asm/errno.h
> +++ b/tools/arch/powerpc/include/uapi/asm/errno.h
> @@ -2,6 +2,7 @@
>  #ifndef _ASM_POWERPC_ERRNO_H
>  #define _ASM_POWERPC_ERRNO_H
>
> +#undef EDEADLOCK
>  #include <asm-generic/errno.h>
>
>  #undef EDEADLOCK
> --
> 2.25.1
>