Thread (9 messages) flat view 9 messages, 2 authors, 2021-07-17

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

From: Andrii Nakryiko <hidden>
Date: 2021-07-17 00:33:20
Also in: bpf, linux-kselftest, lkml

On Fri, Jul 16, 2021 at 3:47 PM Alan Maguire [off-list ref] wrote:
quoted hunk ↗ jump to hunk
By using the stack for this small structure, we avoid the need
for freeing memory in error paths.

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alan Maguire <redacted>
---
 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);
can't happen, removed, please pay attention to the surrounding code
quoted hunk ↗ jump to hunk
@@ -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);
-
added resetting to NULL here, so that we don't have an accidental
dangling pointers
        return libbpf_err(ret);
 }
--
1.8.3.1
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