[PATCH bpf-next v3 5/8] tools: replace btf__get_from_id() with btf__load_from_kernel_by_id()

Quentin Monnet
2021-07-29T16:20:50Z

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>
Acked-by: John Fastabend <john.fastabend@gmail.com>
---
tools/bpf/bpftool/btf.c | 8 ++-----
tools/bpf/bpftool/btf_dumper.c | 6 +++--
tools/bpf/bpftool/map.c | 14 ++++++------
tools/bpf/bpftool/prog.c | 24 +++++++++++++-------
tools/perf/util/bpf-event.c | 7 +++---
tools/perf/util/bpf_counter.c | 9 ++++++--
tools/testing/selftests/bpf/prog_tests/btf.c | 3 ++-
7 files changed, 42 insertions(+), 29 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) {
diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
index 17a9844e4fbf..996d025b8ed8 100644
--- a/tools/perf/util/bpf-event.c
+++ b/tools/perf/util/bpf-event.c
@@ -223,10 +223,10 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_session *session,
free(info_linear);
return -1;
}
- if (btf__get_from_id(info->btf_id, &btf)) {
+ btf = btf__load_from_kernel_by_id(info->btf_id);
+ if (libbpf_get_error(btf)) {
pr_debug("%s: failed to get BTF of id %u, aborting\n", __func__, info->btf_id);
err = -1;
- btf = NULL;
goto out;
}
perf_env__fetch_btf(env, info->btf_id, btf);
@@ -478,7 +478,8 @@ static void perf_env__add_bpf_info(struct perf_env *env, u32 id)
if (btf_id == 0)
goto out;

- if (btf__get_from_id(btf_id, &btf)) {
+ btf = btf__load_from_kernel_by_id(btf_id);
+ if (libbpf_get_error(btf)) {
pr_debug("%s: failed to get BTF of id %u, aborting\n",
__func__, btf_id);
goto out;
diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c
index beca55129b0b..ba0f20853651 100644
--- a/tools/perf/util/bpf_counter.c
+++ b/tools/perf/util/bpf_counter.c
@@ -74,12 +74,17 @@ static char *bpf_target_prog_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) {
pr_debug("prog FD %d doesn't have valid btf\n", tgt_fd);
goto out;
}

+ btf = btf__load_from_kernel_by_id(info_linear->info.btf_id);
+ if (libbpf_get_error(btf)) {
+ pr_debug("failed to load btf for prog FD %d\n", 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) {
diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c b/tools/testing/selftests/bpf/prog_tests/btf.c
index 68e415f4d33c..649f87382c8d 100644
--- a/tools/testing/selftests/bpf/prog_tests/btf.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf.c
@@ -4350,7 +4350,8 @@ static void do_test_file(unsigned int test_num)
goto done;
}

- err = btf__get_from_id(info.btf_id, &btf);
+ btf = btf__load_from_kernel_by_id(info.btf_id);
+ err = libbpf_get_error(btf);
if (CHECK(err, "cannot get btf from kernel, err: %d", err))
goto done;

--
2.30.2