[PATCH bpf-next] libbpf: deprecate bpf_object__unload() API

[Hengqi Chen <hengqi.chen@gmail.com>]

BPF objects are not re-loadable after unload. User are expected to use
bpf_object__close() to unload and free up resources in one operation.
No need to expose bpf_object__unload() as a public API, deprecate it.[0]
Remove bpf_object__unload() inside bpf_object__load_xattr(), it is the
caller's responsibility to free up resources, otherwise, the following
code path will cause double-free problem when loading failed:

    bpf_prog_load
        bpf_prog_load_xattr
            bpf_object__load
                bpf_object__load_xattr

Replace bpf_object__unload() inside bpf_object__close() with the necessary
cleanup operations to avoid compilation error.

  [0] Closes: https://github.com/libbpf/libbpf/issues/290

Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
---
 tools/lib/bpf/libbpf.c | 8 +++++---
 tools/lib/bpf/libbpf.h | 3 ++-
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 8f579c6666b2..c56b466c5461 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -6931,7 +6931,6 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
 		if (obj->maps[i].pinned && !obj->maps[i].reused)
 			bpf_map__unpin(&obj->maps[i], NULL);
 
-	bpf_object__unload(obj);
 	pr_warn("failed to load object '%s'\n", obj->path);
 	return libbpf_err(err);
 }
@@ -7540,12 +7539,15 @@ void bpf_object__close(struct bpf_object *obj)
 
 	bpf_gen__free(obj->gen_loader);
 	bpf_object__elf_finish(obj);
-	bpf_object__unload(obj);
 	btf__free(obj->btf);
 	btf_ext__free(obj->btf_ext);
 
-	for (i = 0; i < obj->nr_maps; i++)
+	for (i = 0; i < obj->nr_maps; i++) {
+		zclose(obj->maps[i].fd);
+		if (obj->maps[i].st_ops)
+			zfree(&obj->maps[i].st_ops->kern_vdata);
 		bpf_map__destroy(&obj->maps[i]);
+	}
 
 	zfree(&obj->btf_custom_path);
 	zfree(&obj->kconfig);
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 2f6f0e15d1e7..748f7dabe4c7 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -147,7 +147,8 @@ struct bpf_object_load_attr {
 /* Load/unload object into/from kernel */
 LIBBPF_API int bpf_object__load(struct bpf_object *obj);
 LIBBPF_API int bpf_object__load_xattr(struct bpf_object_load_attr *attr);
-LIBBPF_API int bpf_object__unload(struct bpf_object *obj);
+LIBBPF_API LIBBPF_DEPRECATED("bpf_object__unload() is deprecated, use bpf_object__close() instead")
+int bpf_object__unload(struct bpf_object *obj);
 
 LIBBPF_API const char *bpf_object__name(const struct bpf_object *obj);
 LIBBPF_API unsigned int bpf_object__kversion(const struct bpf_object *obj);
-- 
2.25.1