Re: [PATCH v2] RISC-V: fix barrier() use in <vdso/processor.h>

[Nick Desaulniers]

On Tue, Nov 17, 2020 at 11:31 AM Randy Dunlap <rdunlap@xxxxxxxxxxxxx> wrote:
>
> riscv's <vdso/processor.h> uses barrier() so it should
> #include <asm/barrier.h> to prevent build errors.
>
> Fixes this build error:
>   CC [M]  drivers/net/ethernet/emulex/benet/be_main.o
> In file included from ./include/vdso/processor.h:10,
>                  from ./arch/riscv/include/asm/processor.h:11,
>                  from ./include/linux/prefetch.h:15,
>                  from drivers/net/ethernet/emulex/benet/be_main.c:14:
> ./arch/riscv/include/asm/vdso/processor.h: In function 'cpu_relax':
> ./arch/riscv/include/asm/vdso/processor.h:14:2: error: implicit declaration of function 'barrier' [-Werror=implicit-function-declaration]
>    14 |  barrier();
>
> This happens with a total of 5 networking drivers -- they all use
> <linux/prefetch.h>.
>
> rv64 and rv32 allmodconfig now build cleanly after this patch.
>
> Fixes: 3347acc6fcd4 ("compiler.h: fix barrier_data() on clang")
> Fixes: ad5d1122b82f ("riscv: use vDSO common flow to reduce the latency of the time-related functions")
> Reported-by: Andreas Schwab <schwab@xxxxxxxxxxxxxx>
> Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> Cc: Arvind Sankar <nivedita@xxxxxxxxxxxx>
> Cc: linux-riscv@xxxxxxxxxxxxxxxxxxx
> Cc: clang-built-linux@xxxxxxxxxxxxxxxx
> Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> Cc: Nathan Chancellor <natechancellor@xxxxxxxxx>
> Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
> Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
> Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx>

Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Link: https://github.com/ClangBuiltLinux/linux/issues/1202

> ---
> v2: update Fixes: tags (Nick);
>     also built allmodconfig cleanly on rv32;
>
>  arch/riscv/include/asm/vdso/processor.h |    2 ++
>  1 file changed, 2 insertions(+)
>
> --- lnx-510-rc4.orig/arch/riscv/include/asm/vdso/processor.h
> +++ lnx-510-rc4/arch/riscv/include/asm/vdso/processor.h
> @@ -4,6 +4,8 @@
>
>  #ifndef __ASSEMBLY__
>
> +#include <asm/barrier.h>
> +
>  static inline void cpu_relax(void)
>  {
>  #ifdef __riscv_muldiv



-- 
Thanks,
~Nick Desaulniers