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Subject[PATCH bpf-next] libbpf: Add ability to clear per-program load flags
Date
Recently, bpf_program__flags and bpf_program__set_extra_flags were
introduced to the libbpf API but they only allow adding load flags.

We have a use-case where we construct a skeleton with a sleepable
program and if it fails to load then we want to make it non-sleepable by
clearing BPF_F_SLEEPABLE.

Signed-off-by: Florent Revest <revest@chromium.org>
---
tools/lib/bpf/libbpf.c | 9 +++++++++
tools/lib/bpf/libbpf.h | 1 +
tools/lib/bpf/libbpf.map | 1 +
3 files changed, 11 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index de7e09a6b5ec..dcb7fced5fd2 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -8305,6 +8305,15 @@ int bpf_program__set_extra_flags(struct bpf_program *prog, __u32 extra_flags)
return 0;
}

+int bpf_program__clear_flags(struct bpf_program *prog, __u32 flags)
+{
+ if (prog->obj->loaded)
+ return libbpf_err(-EBUSY);
+
+ prog->prog_flags &= ~flags;
+ return 0;
+}
+
#define SEC_DEF(sec_pfx, ptype, atype, flags, ...) { \
.sec = sec_pfx, \
.prog_type = BPF_PROG_TYPE_##ptype, \
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 4ec69f224342..08f108e49841 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -495,6 +495,7 @@ bpf_program__set_expected_attach_type(struct bpf_program *prog,

LIBBPF_API __u32 bpf_program__flags(const struct bpf_program *prog);
LIBBPF_API int bpf_program__set_extra_flags(struct bpf_program *prog, __u32 extra_flags);
+LIBBPF_API int bpf_program__clear_flags(struct bpf_program *prog, __u32 flags);

LIBBPF_API int
bpf_program__set_attach_target(struct bpf_program *prog, int attach_prog_fd,
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 6a59514a48cf..eeff700240dc 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -401,6 +401,7 @@ LIBBPF_0.6.0 {
bpf_program__insn_cnt;
bpf_program__insns;
bpf_program__set_extra_flags;
+ bpf_program__clear_flags;
btf__add_btf;
btf__add_decl_tag;
btf__add_type_tag;
--
2.34.0.rc2.393.gf8c9666880-goog
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