Re: [PATCH v3 07/10] perf: Cleanup for HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT

[Adrian Hunter]

On 4/07/21 10:16 am, Leo Yan wrote:
> Since the __sync functions have been dropped, This patch removes unused
> build and checking for HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT in perf tool.
> 
> Note, there have a test for SYNC_COMPARE_AND_SWAP and the test file is
> located in build/feature/test-sync-compare-and-swap.c.  Since there
> still has several components using the sync functions, it's deliberately
> to not be removed.

I don't quite follow that.  If they aren't using the feature test
macro, then why keep the feature test?

> 
>   $ cd linux/tools
>   $ git grep __sync_val_compare_and_swap | awk '{ printf $1"\n" }'
>   build/feature/test-sync-compare-and-swap.c:
>   include/asm-generic/atomic-gcc.h:
>   testing/selftests/bpf/progs/atomics.c:
>   testing/selftests/bpf/progs/atomics.c:
>   testing/selftests/bpf/progs/atomics.c:
>   testing/selftests/bpf/progs/atomics.c:
>   testing/selftests/futex/include/atomic.h:
>   testing/selftests/futex/include/futextest.h:
> 
> Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
> ---
>  tools/perf/Makefile.config | 4 ----
>  tools/perf/util/auxtrace.c | 5 -----
>  2 files changed, 9 deletions(-)
> 
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index eb8e487ef90b..4a0d9a6defc7 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -349,10 +349,6 @@ CXXFLAGS += $(INC_FLAGS)
>  
>  LIBPERF_CFLAGS := $(CORE_CFLAGS) $(EXTRA_CFLAGS)
>  
> -ifeq ($(feature-sync-compare-and-swap), 1)
> -  CFLAGS += -DHAVE_SYNC_COMPARE_AND_SWAP_SUPPORT
> -endif
> -
>  ifeq ($(feature-pthread-attr-setaffinity-np), 1)
>    CFLAGS += -DHAVE_PTHREAD_ATTR_SETAFFINITY_NP
>  endif
> diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
> index 44bd04dbb6d6..db6255b55c90 100644
> --- a/tools/perf/util/auxtrace.c
> +++ b/tools/perf/util/auxtrace.c
> @@ -130,11 +130,6 @@ int auxtrace_mmap__mmap(struct auxtrace_mmap *mm,
>  		return 0;
>  	}
>  
> -#if BITS_PER_LONG != 64 && !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
> -	pr_err("Cannot use AUX area tracing mmaps\n");
> -	return -1;
> -#endif
> -
>  	pc->aux_offset = mp->offset;
>  	pc->aux_size = mp->len;
>  
>