[PATCH bpf-next v3 1/3] Add error returns to two API functions

[grantseltzer <grantseltzer@xxxxxxxxx>]

From: Grant Seltzer <grantseltzer@xxxxxxxxx>

This adds an error return to the following API functions:

- bpf_program__set_expected_attach_type()
- bpf_program__set_type()

In both cases, the error occurs when the BPF object has
already been loaded when the function is called. In this
case -EBUSY is returned.

Signed-off-by: Grant Seltzer <grantseltzer@xxxxxxxxx>
---
 tools/lib/bpf/libbpf.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index bf4f7ac54ebf..0ed1a8c9c398 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -8551,8 +8551,11 @@ enum bpf_prog_type bpf_program__type(const struct bpf_program *prog)
 	return prog->type;
 }
 
-void bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type)
+int bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type)
 {
+	if (prog->obj->loaded)
+		return libbpf_err(-EBUSY);
+
 	prog->type = type;
 }
 
@@ -8598,10 +8601,14 @@ enum bpf_attach_type bpf_program__expected_attach_type(const struct bpf_program
 	return prog->expected_attach_type;
 }
 
-void bpf_program__set_expected_attach_type(struct bpf_program *prog,
+int bpf_program__set_expected_attach_type(struct bpf_program *prog,
 					   enum bpf_attach_type type)
 {
+	if (prog->obj->loaded)
+		return libbpf_err(-EBUSY);
+
 	prog->expected_attach_type = type;
+	return 0;
 }
 
 __u32 bpf_program__flags(const struct bpf_program *prog)
-- 
2.34.1