[PATCH v2 bpf-next] libbpf: make DECLARE_LIBBPF_OPTS macro strictly a variable declaration
From: Andrii Nakryiko <hidden>
Date: 2019-10-22 17:21:10
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [library] (libbpf), bpf [selftests] (test runners & infrastructure), bpf [tooling] (bpftool), kernel selftest framework, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Quentin Monnet, Shuah Khan, Linus Torvalds
LIBBPF_OPTS is implemented as a mix of field declaration and memset + assignment. This makes it neither variable declaration nor purely statements, which is a problem, because you can't mix it with either other variable declarations nor other function statements, because C90 compiler mode emits warning on mixing all that together. This patch changes LIBBPF_OPTS into a strictly declaration of variable and solves this problem, as can be seen in case of bpftool, which previously would emit compiler warning, if done this way (LIBBPF_OPTS as part of function variables declaration block). This patch also renames LIBBPF_OPTS into DECLARE_LIBBPF_OPTS to follow kernel convention for similar macros more closely. v1->v2: - rename LIBBPF_OPTS into DECLARE_LIBBPF_OPTS (Jakub Sitnicki). Signed-off-by: Andrii Nakryiko <redacted> --- tools/bpf/bpftool/prog.c | 8 ++++---- tools/lib/bpf/libbpf.c | 4 ++-- tools/lib/bpf/libbpf.h | 19 ++++++++++++------- .../selftests/bpf/prog_tests/attach_probe.c | 2 +- .../selftests/bpf/prog_tests/core_reloc.c | 2 +- .../bpf/prog_tests/reference_tracking.c | 2 +- 6 files changed, 21 insertions(+), 16 deletions(-)
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 27da96a797ab..4535c863d2cd 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c@@ -1091,8 +1091,11 @@ static int do_run(int argc, char **argv) static int load_with_options(int argc, char **argv, bool first_prog_only) { - struct bpf_object_load_attr load_attr = { 0 }; enum bpf_prog_type common_prog_type = BPF_PROG_TYPE_UNSPEC; + DECLARE_LIBBPF_OPTS(bpf_object_open_opts, open_opts, + .relaxed_maps = relaxed_maps, + ); + struct bpf_object_load_attr load_attr = { 0 }; enum bpf_attach_type expected_attach_type; struct map_replace *map_replace = NULL; struct bpf_program *prog = NULL, *pos;
@@ -1106,9 +1109,6 @@ static int load_with_options(int argc, char **argv, bool first_prog_only) const char *file; int idx, err; - LIBBPF_OPTS(bpf_object_open_opts, open_opts, - .relaxed_maps = relaxed_maps, - ); if (!REQ_ARGS(2)) return -1;
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 803219d6898c..8b4d765c422b 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c@@ -3678,7 +3678,7 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, static struct bpf_object * __bpf_object__open_xattr(struct bpf_object_open_attr *attr, int flags) { - LIBBPF_OPTS(bpf_object_open_opts, opts, + DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts, .relaxed_maps = flags & MAPS_RELAX_COMPAT, );
@@ -3730,7 +3730,7 @@ struct bpf_object * bpf_object__open_buffer(const void *obj_buf, size_t obj_buf_sz, const char *name) { - LIBBPF_OPTS(bpf_object_open_opts, opts, + DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts, .object_name = name, /* wrong default, but backwards-compatible */ .relaxed_maps = true,
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 0fdf086beba7..c63e2ff84abc 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h@@ -75,14 +75,19 @@ struct bpf_object_open_attr { * have all the padding bytes initialized to zero. It's not guaranteed though, * when copying literal, that compiler won't copy garbage in literal's padding * bytes, but that's the best way I've found and it seems to work in practice. + * + * Macro declares opts struct of given type and name, zero-initializes, + * including any extra padding, it with memset() and then assigns initial + * values provided by users in struct initializer-syntax as varargs. */ -#define LIBBPF_OPTS(TYPE, NAME, ...) \ - struct TYPE NAME; \ - memset(&NAME, 0, sizeof(struct TYPE)); \ - NAME = (struct TYPE) { \ - .sz = sizeof(struct TYPE), \ - __VA_ARGS__ \ - } +#define DECLARE_LIBBPF_OPTS(TYPE, NAME, ...) \ + struct TYPE NAME = ({ \ + memset(&NAME, 0, sizeof(struct TYPE)); \ + (struct TYPE) { \ + .sz = sizeof(struct TYPE), \ + __VA_ARGS__ \ + }; \ + }) struct bpf_object_open_opts { /* size of this struct, for forward/backward compatiblity */
diff --git a/tools/testing/selftests/bpf/prog_tests/attach_probe.c b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
index 0ee1ce100a4a..a83111a32d4a 100644
--- a/tools/testing/selftests/bpf/prog_tests/attach_probe.c
+++ b/tools/testing/selftests/bpf/prog_tests/attach_probe.c@@ -50,7 +50,7 @@ void test_attach_probe(void) const int kprobe_idx = 0, kretprobe_idx = 1; const int uprobe_idx = 2, uretprobe_idx = 3; const char *obj_name = "attach_probe"; - LIBBPF_OPTS(bpf_object_open_opts, open_opts, + DECLARE_LIBBPF_OPTS(bpf_object_open_opts, open_opts, .object_name = obj_name, .relaxed_maps = true, );
diff --git a/tools/testing/selftests/bpf/prog_tests/core_reloc.c b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
index 523dca82dc82..09dfa75fe948 100644
--- a/tools/testing/selftests/bpf/prog_tests/core_reloc.c
+++ b/tools/testing/selftests/bpf/prog_tests/core_reloc.c@@ -377,7 +377,7 @@ void test_core_reloc(void) if (!test__start_subtest(test_case->case_name)) continue; - LIBBPF_OPTS(bpf_object_open_opts, opts, + DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts, .relaxed_core_relocs = test_case->relaxed_core_relocs, );
diff --git a/tools/testing/selftests/bpf/prog_tests/reference_tracking.c b/tools/testing/selftests/bpf/prog_tests/reference_tracking.c
index 4493ba277bd7..fc0d7f4f02cf 100644
--- a/tools/testing/selftests/bpf/prog_tests/reference_tracking.c
+++ b/tools/testing/selftests/bpf/prog_tests/reference_tracking.c@@ -5,7 +5,7 @@ void test_reference_tracking(void) { const char *file = "test_sk_lookup_kern.o"; const char *obj_name = "ref_track"; - LIBBPF_OPTS(bpf_object_open_opts, open_opts, + DECLARE_LIBBPF_OPTS(bpf_object_open_opts, open_opts, .object_name = obj_name, .relaxed_maps = true, );
--
2.17.1