linux-kernel - Re: [PATCH v1 1/2] perf bpf-event: Use libbpf version rather than feature check

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Message-ID: <aOAiUgWjbdwBZTzO@x1>
Date: Fri, 3 Oct 2025 16:21:54 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Blake Jones <blakejones@...gle.com>, linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH v1 1/2] perf bpf-event: Use libbpf version rather than
 feature check

On Thu, Oct 02, 2025 at 06:23:48PM -0700, Ian Rogers wrote:
> The feature check guarded the -DHAVE_LIBBPF_STRINGS_SUPPORT is
> unnecessary as it is sufficient and easier to use the
> LIBBPF_CURRENT_VERSION_GEQ macro.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  tools/perf/Makefile.config  | 7 -------
>  tools/perf/builtin-check.c  | 1 +
>  tools/perf/util/bpf-event.c | 2 --
>  tools/perf/util/bpf-utils.h | 5 +++++
>  4 files changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index 6cdb96576cb8..b0e15721c5a5 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -596,13 +596,6 @@ ifndef NO_LIBELF
>  	  LIBBPF_INCLUDE = $(LIBBPF_DIR)/..
>          endif
>        endif
> -
> -      FEATURE_CHECK_CFLAGS-libbpf-strings="-I$(LIBBPF_INCLUDE)"
> -      $(call feature_check,libbpf-strings)
> -      ifeq ($(feature-libbpf-strings), 1)
> -        $(call detected,CONFIG_LIBBPF_STRINGS)
> -        CFLAGS += -DHAVE_LIBBPF_STRINGS_SUPPORT
> -      endif
>      endif
>    endif # NO_LIBBPF
>  endif # NO_LIBELF
> diff --git a/tools/perf/builtin-check.c b/tools/perf/builtin-check.c
> index 7fd054760e47..8c0668911fb1 100644
> --- a/tools/perf/builtin-check.c
> +++ b/tools/perf/builtin-check.c
> @@ -1,6 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0
>  #include "builtin.h"
>  #include "color.h"
> +#include "util/bpf-utils.h"
>  #include "util/debug.h"
>  #include "util/header.h"
>  #include <tools/config.h>
> diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
> index 59f84aef91b4..2298cd396c42 100644
> --- a/tools/perf/util/bpf-event.c
> +++ b/tools/perf/util/bpf-event.c
> @@ -288,9 +288,7 @@ static void format_btf_variable(struct btf *btf, char *buf, size_t buf_size,
>  		.sz = sizeof(struct btf_dump_type_data_opts),
>  		.skip_names = 1,
>  		.compact = 1,
> -#if LIBBPF_CURRENT_VERSION_GEQ(1, 7)
>  		.emit_strings = 1,
> -#endif

I see, this is already under HAVE_LIBBPF_STRINGS_SUPPORT

Applying,

- Arnaldo

>  	};
>  	struct btf_dump *d;
>  	size_t btf_size;
> diff --git a/tools/perf/util/bpf-utils.h b/tools/perf/util/bpf-utils.h
> index eafc43b8731f..a8bc1a232968 100644
> --- a/tools/perf/util/bpf-utils.h
> +++ b/tools/perf/util/bpf-utils.h
> @@ -14,6 +14,11 @@
>         (LIBBPF_MAJOR_VERSION > (major) ||                              \
>          (LIBBPF_MAJOR_VERSION == (major) && LIBBPF_MINOR_VERSION >= (minor)))
>  
> +#if LIBBPF_CURRENT_VERSION_GEQ(1, 7)
> +// libbpf 1.7+ support the btf_dump_type_data_opts.emit_strings option.
> +#define HAVE_LIBBPF_STRINGS_SUPPORT 1
> +#endif
> +
>  /*
>   * Get bpf_prog_info in continuous memory
>   *
> -- 
> 2.51.0.618.g983fd99d29-goog