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Message-ID: <20191022172100.3281465-1-andriin@fb.com>
Date: Tue, 22 Oct 2019 10:21:00 -0700
From: Andrii Nakryiko <andriin@...com>
To: <bpf@...r.kernel.org>, <netdev@...r.kernel.org>, <ast@...com>,
<daniel@...earbox.net>
CC: <andrii.nakryiko@...il.com>, <kernel-team@...com>,
Andrii Nakryiko <andriin@...com>
Subject: [PATCH v2 bpf-next] libbpf: make DECLARE_LIBBPF_OPTS macro strictly a variable declaration
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 <andriin@...com>
---
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
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