[RFC bpf-next v8 9/9] bpf: Optimize the performance of find_bpffs_btf_enums

[Donglin Peng <dolinux.peng@gmail.com>]

From: pengdonglin <pengdonglin@xiaomi.com>

Currently, vmlinux BTF is unconditionally sorted during
the build phase. The function btf_find_by_name_kind
executes the binary search branch, so find_bpffs_btf_enums
can be optimized by using btf_find_by_name_kind.

Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Ihor Solodrai <ihor.solodrai@linux.dev>
Cc: Xiaoqin Zhang <zhangxiaoqin@xiaomi.com>
Signed-off-by: pengdonglin <pengdonglin@xiaomi.com>
---
 kernel/bpf/inode.c | 42 +++++++++++++++++++-----------------------
 1 file changed, 19 insertions(+), 23 deletions(-)

diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 81780bcf8d25..781c2c3181a4 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -605,10 +605,18 @@ struct bpffs_btf_enums {
 
 static int find_bpffs_btf_enums(struct bpffs_btf_enums *info)
 {
+	struct {
+		const struct btf_type **type;
+		const char *name;
+	} btf_enums[] = {
+		{&info->cmd_t,		"bpf_cmd"},
+		{&info->map_t,		"bpf_map_type"},
+		{&info->prog_t,		"bpf_prog_type"},
+		{&info->attach_t,	"bpf_attach_type"},
+	};
 	const struct btf *btf;
 	const struct btf_type *t;
-	const char *name;
-	int i, n;
+	int i, id;
 
 	memset(info, 0, sizeof(*info));
 
@@ -620,30 +628,18 @@ static int find_bpffs_btf_enums(struct bpffs_btf_enums *info)
 
 	info->btf = btf;
 
-	for (i = 1, n = btf_nr_types(btf); i < n; i++) {
-		t = btf_type_by_id(btf, i);
-		if (!btf_type_is_enum(t))
-			continue;
+	for (i = 0; i < ARRAY_SIZE(btf_enums); i++) {
+		id = btf_find_by_name_kind(btf, btf_enums[i].name,
+					   BTF_KIND_ENUM);
+		if (id < 0)
+			goto out;
 
-		name = btf_name_by_offset(btf, t->name_off);
-		if (!name)
-			continue;
-
-		if (strcmp(name, "bpf_cmd") == 0)
-			info->cmd_t = t;
-		else if (strcmp(name, "bpf_map_type") == 0)
-			info->map_t = t;
-		else if (strcmp(name, "bpf_prog_type") == 0)
-			info->prog_t = t;
-		else if (strcmp(name, "bpf_attach_type") == 0)
-			info->attach_t = t;
-		else
-			continue;
-
-		if (info->cmd_t && info->map_t && info->prog_t && info->attach_t)
-			return 0;
+		t = btf_type_by_id(btf, id);
+		*btf_enums[i].type = t;
 	}
 
+	return 0;
+out:
 	return -ESRCH;
 }
 
-- 
2.34.1