netdev - [RFC bpf-next 2/3] libbpf: bpf__find_by_name[_kind] should use btf__get_nr

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Date:   Fri, 13 Nov 2020 18:10:12 +0000
From:   Alan Maguire <alan.maguire@...cle.com>
To:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org
Cc:     kafai@...com, songliubraving@...com, yhs@...com,
        john.fastabend@...il.com, kpsingh@...omium.org,
        rostedt@...dmis.org, mingo@...hat.com, haoluo@...gle.com,
        jolsa@...nel.org, quentin@...valent.com,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: [RFC bpf-next 2/3] libbpf: bpf__find_by_name[_kind] should use btf__get_nr_types()

When operating on split BTF, btf__find_by_name[_kind] will not
iterate over all types since they use btf->nr_types to show
the number of types to iterate over.  For split BTF this is
the number of types _on top of base BTF_, so it will
underestimate the number of types to iterate over, especially
for vmlinux + module BTF, where the latter is much smaller.

Use btf__get_nr_types() instead.

Signed-off-by: Alan Maguire <alan.maguire@...cle.com>
---
 tools/lib/bpf/btf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 2d0d064..0fccf4b 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -679,7 +679,7 @@ __s32 btf__find_by_name(const struct btf *btf, const char *type_name)
 	if (!strcmp(type_name, "void"))
 		return 0;
 
-	for (i = 1; i <= btf->nr_types; i++) {
+	for (i = 1; i <= btf__get_nr_types(btf); i++) {
 		const struct btf_type *t = btf__type_by_id(btf, i);
 		const char *name = btf__name_by_offset(btf, t->name_off);
 
@@ -698,7 +698,7 @@ __s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
 	if (kind == BTF_KIND_UNKN || !strcmp(type_name, "void"))
 		return 0;
 
-	for (i = 1; i <= btf->nr_types; i++) {
+	for (i = 1; i <= btf__get_nr_types(btf); i++) {
 		const struct btf_type *t = btf__type_by_id(btf, i);
 		const char *name;
 
-- 
1.8.3.1