tools: Replace btf__get_from_id() with btf__load_from_kernel_by_id()

Replace the calls to function btf__get_from_id(), which we plan to
deprecate before the library reaches v1.0, with calls to
btf__load_from_kernel_by_id() in tools/ (bpftool, perf, selftests).
Update the surrounding code accordingly (instead of passing a pointer to
the btf struct, get it as a return value from the function).

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210729162028.29512-6-quentin@isovalent.com

4 files changed, 29 insertions, 23 deletions

diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
index 385d5c955cf3..9162a18e84c0 100644
--- a/tools/bpf/bpftool/btf.c
+++ b/tools/bpf/bpftool/btf.c
@@ -580,16 +580,12 @@ static int do_dump(int argc, char **argv)
 	}
 
 	if (!btf) {
-		err = btf__get_from_id(btf_id, &btf);
+		btf = btf__load_from_kernel_by_id(btf_id);
+		err = libbpf_get_error(btf);
 		if (err) {
 			p_err("get btf by id (%u): %s", btf_id, strerror(err));
 			goto done;
 		}
-		if (!btf) {
-			err = -ENOENT;
-			p_err("can't find btf with ID (%u)", btf_id);
-			goto done;
-		}
 	}
 
 	if (dump_c) {
diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
index 7ca54d046362..9c25286a5c73 100644
--- a/tools/bpf/bpftool/btf_dumper.c
+++ b/tools/bpf/bpftool/btf_dumper.c
@@ -64,8 +64,10 @@ static int dump_prog_id_as_func_ptr(const struct btf_dumper *d,
 	}
 	info = &prog_info->info;
 
-	if (!info->btf_id || !info->nr_func_info ||
-	    btf__get_from_id(info->btf_id, &prog_btf))
+	if (!info->btf_id || !info->nr_func_info)
+		goto print;
+	prog_btf = btf__load_from_kernel_by_id(info->btf_id);
+	if (libbpf_get_error(prog_btf))
 		goto print;
 	finfo = u64_to_ptr(info->func_info);
 	func_type = btf__type_by_id(prog_btf, finfo->type_id);
diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 09ae0381205b..7e7f748bb0be 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -807,10 +807,11 @@ static struct btf *get_map_kv_btf(const struct bpf_map_info *info)
 	} else if (info->btf_value_type_id) {
 		int err;
 
-		err = btf__get_from_id(info->btf_id, &btf);
-		if (err || !btf) {
+		btf = btf__load_from_kernel_by_id(info->btf_id);
+		err = libbpf_get_error(btf);
+		if (err) {
 			p_err("failed to get btf");
-			btf = err ? ERR_PTR(err) : ERR_PTR(-ESRCH);
+			btf = ERR_PTR(err);
 		}
 	}
 
@@ -1039,11 +1040,10 @@ static void print_key_value(struct bpf_map_info *info, void *key,
 			    void *value)
 {
 	json_writer_t *btf_wtr;
-	struct btf *btf = NULL;
-	int err;
+	struct btf *btf;
 
-	err = btf__get_from_id(info->btf_id, &btf);
-	if (err) {
+	btf = btf__load_from_kernel_by_id(info->btf_id);
+	if (libbpf_get_error(btf)) {
 		p_err("failed to get btf");
 		return;
 	}
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 9d709b427665..b1996b8f1d42 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -249,10 +249,10 @@ static void show_prog_metadata(int fd, __u32 num_maps)
 	struct bpf_map_info map_info;
 	struct btf_var_secinfo *vsi;
 	bool printed_header = false;
-	struct btf *btf = NULL;
 	unsigned int i, vlen;
 	void *value = NULL;
 	const char *name;
+	struct btf *btf;
 	int err;
 
 	if (!num_maps)
@@ -263,8 +263,8 @@ static void show_prog_metadata(int fd, __u32 num_maps)
 	if (!value)
 		return;
 
-	err = btf__get_from_id(map_info.btf_id, &btf);
-	if (err || !btf)
+	btf = btf__load_from_kernel_by_id(map_info.btf_id);
+	if (libbpf_get_error(btf))
 		goto out_free;
 
 	t_datasec = btf__type_by_id(btf, map_info.btf_value_type_id);
@@ -646,9 +646,12 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode,
 		member_len = info->xlated_prog_len;
 	}
 
-	if (info->btf_id && btf__get_from_id(info->btf_id, &btf)) {
-		p_err("failed to get btf");
-		return -1;
+	if (info->btf_id) {
+		btf = btf__load_from_kernel_by_id(info->btf_id);
+		if (libbpf_get_error(btf)) {
+			p_err("failed to get btf");
+			return -1;
+		}
 	}
 
 	func_info = u64_to_ptr(info->func_info);
@@ -2014,12 +2017,17 @@ static char *profile_target_name(int tgt_fd)
 		return NULL;
 	}
 
-	if (info_linear->info.btf_id == 0 ||
-	    btf__get_from_id(info_linear->info.btf_id, &btf)) {
+	if (info_linear->info.btf_id == 0) {
 		p_err("prog FD %d doesn't have valid btf", tgt_fd);
 		goto out;
 	}
 
+	btf = btf__load_from_kernel_by_id(info_linear->info.btf_id);
+	if (libbpf_get_error(btf)) {
+		p_err("failed to load btf for prog FD %d", tgt_fd);
+		goto out;
+	}
+
 	func_info = u64_to_ptr(info_linear->info.func_info);
 	t = btf__type_by_id(btf, func_info[0].type_id);
 	if (!t) {