linux-kernel - [PATCH v2 bpf-next 3/3] libbpf: btf typed dump does not need to allocate dump data

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Date:   Fri, 16 Jul 2021 23:46:57 +0100
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@...nel.org, morbo@...gle.com,
        shuah@...nel.org, bpf@...r.kernel.org, netdev@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        Alan Maguire <alan.maguire@...cle.com>
Subject: [PATCH v2 bpf-next 3/3] libbpf: btf typed dump does not need to allocate dump data

By using the stack for this small structure, we avoid the need
for freeing memory in error paths.

Suggested-by: Andrii Nakryiko <andrii@...nel.org>
Signed-off-by: Alan Maguire <alan.maguire@...cle.com>
---
 tools/lib/bpf/btf_dump.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index e5fbfb8..bd8e005 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -2240,6 +2240,7 @@ int btf_dump__dump_type_data(struct btf_dump *d, __u32 id,
 			     const void *data, size_t data_sz,
 			     const struct btf_dump_type_data_opts *opts)
 {
+	struct btf_dump_data typed_dump = {};
 	const struct btf_type *t;
 	int ret;
 
@@ -2250,7 +2251,7 @@ int btf_dump__dump_type_data(struct btf_dump *d, __u32 id,
 	if (!t)
 		return libbpf_err(-ENOENT);
 
-	d->typed_dump = calloc(1, sizeof(struct btf_dump_data));
+	d->typed_dump = &typed_dump;
 	if (!d->typed_dump)
 		return libbpf_err(-ENOMEM);
 
@@ -2269,7 +2270,5 @@ int btf_dump__dump_type_data(struct btf_dump *d, __u32 id,
 
 	ret = btf_dump_dump_type_data(d, NULL, t, id, data, 0, 0);
 
-	free(d->typed_dump);
-
 	return libbpf_err(ret);
 }
-- 
1.8.3.1