netdev - [PATCH bpf 2/2] libbpf: allow loading empty BTFs

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Message-ID: <20210110070341.1380086-2-andrii@kernel.org>
Date:   Sat, 9 Jan 2021 23:03:41 -0800
From:   Andrii Nakryiko <andrii@...nel.org>
To:     <bpf@...r.kernel.org>, <netdev@...r.kernel.org>, <ast@...com>,
        <daniel@...earbox.net>
CC:     <andrii@...nel.org>, <kernel-team@...com>,
        Christopher William Snowhill <chris@...e54.net>
Subject: [PATCH bpf 2/2] libbpf: allow loading empty BTFs

Empty BTFs do come up (e.g., simple kernel modules with no new types and
strings, compared to the vmlinux BTF) and there is nothing technically wrong
with them. So remove unnecessary check preventing loading empty BTFs.

Reported-by: Christopher William Snowhill <chris@...e54.net>
Fixes: ("d8123624506c libbpf: Fix BTF data layout checks and allow empty BTF")
Signed-off-by: Andrii Nakryiko <andrii@...nel.org>
---
 tools/lib/bpf/btf.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 3c3f2bc6c652..9970a288dda5 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -240,11 +240,6 @@ static int btf_parse_hdr(struct btf *btf)
 	}
 
 	meta_left = btf->raw_size - sizeof(*hdr);
-	if (!meta_left) {
-		pr_debug("BTF has no data\n");
-		return -EINVAL;
-	}
-
 	if (meta_left < hdr->str_off + hdr->str_len) {
 		pr_debug("Invalid BTF total size:%u\n", btf->raw_size);
 		return -EINVAL;
-- 
2.24.1