From: Andrii Nakryiko <andriin@fb.com>
Date: Thu, 16 Jan 2020 22:07:59 -0800
Subject: libbpf: Simplify BTF initialization logic
Patch-mainline: v5.6-rc1
Git-commit: b7d7f3e185b6e643dcd49d1486b11cade8519008
References: bsc#1177028

Current implementation of bpf_object's BTF initialization is very convoluted
and thus prone to errors. It doesn't have to be like that. This patch
simplifies it significantly.

This code also triggered static analysis issues over logically dead code due
to redundant error checks. This simplification should fix that as well.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200117060801.1311525-3-andriin@fb.com
Acked-by: Gary Lin <glin@suse.com>
---
 tools/lib/bpf/libbpf.c |   19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2298,16 +2298,18 @@ static int bpf_object__init_btf(struct b
 				Elf_Data *btf_data,
 				Elf_Data *btf_ext_data)
 {
-	bool btf_required = bpf_object__is_btf_mandatory(obj);
-	int err = 0;
+	int err = -ENOENT;
 
 	if (btf_data) {
 		obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
 		if (IS_ERR(obj->btf)) {
+			err = PTR_ERR(obj->btf);
+			obj->btf = NULL;
 			pr_warning("Error loading ELF section %s: %d.\n",
 				   BTF_ELF_SEC, err);
 			goto out;
 		}
+		err = 0;
 	}
 	if (btf_ext_data) {
 		if (!obj->btf) {
@@ -2325,18 +2327,9 @@ static int bpf_object__init_btf(struct b
 		}
 	}
 out:
-	if (err || IS_ERR(obj->btf)) {
-		if (btf_required)
-			err = err ? : PTR_ERR(obj->btf);
-		else
-			err = 0;
-		if (!IS_ERR_OR_NULL(obj->btf))
-			btf__free(obj->btf);
-		obj->btf = NULL;
-	}
-	if (btf_required && !obj->btf) {
+	if (err && bpf_object__is_btf_mandatory(obj)) {
 		pr_warning("BTF is required, but is missing or corrupted.\n");
-		return err == 0 ? -ENOENT : err;
+		return err;
 	}
 	return 0;
 }