[PATCH] tools/bpftool: Fix error return code in do_skeleton()

[YueHaibing]

The error return code should be PTR_ERR(obj) other than
PTR_ERR(NULL).

Fixes: 5dc7a8b21144 ("bpftool, selftests/bpf: Embed object file inside skeleton")
Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
---
 tools/bpf/bpftool/gen.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index 10de76b296ba..35f62273cdbd 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -305,8 +305,9 @@ static int do_skeleton(int argc, char **argv)
 	opts.object_name = obj_name;
 	obj = bpf_object__open_mem(obj_data, file_sz, &opts);
 	if (IS_ERR(obj)) {
+		err = PTR_ERR(obj);
+		p_err("failed to open BPF object file: %ld", err);
 		obj = NULL;
-		p_err("failed to open BPF object file: %ld", PTR_ERR(obj));
 		goto out;
 	}
 
-- 
2.17.1