libbpf: Cleanup struct bpf_core_cand.

mainline inclusion
from mainline-5.17-rc1
commit 03d5b991
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=03d5b99138dd8c7bfb838396acb180bd515ebf06

-------------------------------------------------

Remove two redundant fields from struct bpf_core_cand.
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-8-alexei.starovoitov@gmail.com
(cherry picked from commit 03d5b991)
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

Conflicts:
	tools/lib/bpf/libbpf.c
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

tools/lib/bpf/libbpf.c

@@ -5147,15 +5147,18 @@ static int bpf_core_add_cands(struct bpf_core_cand *local_cand,
 			      struct bpf_core_cand_list *cands)
 {
 	struct bpf_core_cand *new_cands, *cand;
-	const struct btf_type *t;
-	const char *targ_name;
+	const struct btf_type *t, *local_t;
+	const char *targ_name, *local_name;
 	size_t targ_essent_len;
 	int n, i;
 
+	local_t = btf__type_by_id(local_cand->btf, local_cand->id);
+	local_name = btf__str_by_offset(local_cand->btf, local_t->name_off);
+
 	n = btf__get_nr_types(targ_btf);
 	for (i = targ_start_id; i <= n; i++) {
 		t = btf__type_by_id(targ_btf, i);
-		if (btf_kind(t) != btf_kind(local_cand->t))
+		if (btf_kind(t) != btf_kind(local_t))
 			continue;
 
 		targ_name = btf__name_by_offset(targ_btf, t->name_off);
@@ -5166,12 +5169,12 @@ static int bpf_core_add_cands(struct bpf_core_cand *local_cand,
 		if (targ_essent_len != local_essent_len)
 			continue;
 
-		if (strncmp(local_cand->name, targ_name, local_essent_len) != 0)
+		if (strncmp(local_name, targ_name, local_essent_len) != 0)
 			continue;
 
 		pr_debug("CO-RE relocating [%d] %s %s: found target candidate [%d] %s %s in [%s]\n",
-			 local_cand->id, btf_kind_str(local_cand->t),
-			 local_cand->name, i, btf_kind_str(t), targ_name,
+			 local_cand->id, btf_kind_str(local_t),
+			 local_name, i, btf_kind_str(t), targ_name,
 			 targ_btf_name);
 		new_cands = libbpf_reallocarray(cands->cands, cands->len + 1,
 					      sizeof(*cands->cands));
@@ -5180,8 +5183,6 @@ static int bpf_core_add_cands(struct bpf_core_cand *local_cand,
 
 		cand = &new_cands[cands->len];
 		cand->btf = targ_btf;
-		cand->t = t;
-		cand->name = targ_name;
 		cand->id = i;
 
 		cands->cands = new_cands;
@@ -5288,18 +5289,21 @@ bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 l
 	struct bpf_core_cand local_cand = {};
 	struct bpf_core_cand_list *cands;
 	const struct btf *main_btf;
+	const struct btf_type *local_t;
+	const char *local_name;
 	size_t local_essent_len;
 	int err, i;
 
 	local_cand.btf = local_btf;
-	local_cand.t = btf__type_by_id(local_btf, local_type_id);
-	if (!local_cand.t)
+	local_cand.id = local_type_id;
+	local_t = btf__type_by_id(local_btf, local_type_id);
+	if (!local_t)
 		return ERR_PTR(-EINVAL);
 
-	local_cand.name = btf__name_by_offset(local_btf, local_cand.t->name_off);
-	if (str_is_empty(local_cand.name))
+	local_name = btf__name_by_offset(local_btf, local_t->name_off);
+	if (str_is_empty(local_name))
 		return ERR_PTR(-EINVAL);
-	local_essent_len = bpf_core_essential_name_len(local_cand.name);
+	local_essent_len = bpf_core_essential_name_len(local_name);
 
 	cands = calloc(1, sizeof(*cands));
 	if (!cands)

tools/lib/bpf/relo_core.h

@@ -8,8 +8,6 @@
 
 struct bpf_core_cand {
 	const struct btf *btf;
-	const struct btf_type *t;
-	const char *name;
 	__u32 id;
 };