| Message ID | 20200729232148.896125-1-andriin@fb.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf-next] libbpf: make destructors more robust by handling ERR_PTR(err) cases | expand |
On Wed, Jul 29, 2020 at 4:22 PM Andrii Nakryiko <andriin@fb.com> wrote: > > Most of libbpf "constructors" on failure return ERR_PTR(err) result encoded as > a pointer. It's a common mistake to eventually pass such malformed pointers > into xxx__destroy()/xxx__free() "destructors". So instead of fixing up > clean up code in selftests and user programs, handle such error pointers in > destructors themselves. This works beautifully for NULL pointers passed to > destructors, so might as well just work for error pointers. > > Suggested-by: Song Liu <songliubraving@fb.com> > Signed-off-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Song Liu <songliubraving@fb.com>
On 7/30/20 1:21 AM, Andrii Nakryiko wrote: > Most of libbpf "constructors" on failure return ERR_PTR(err) result encoded as > a pointer. It's a common mistake to eventually pass such malformed pointers > into xxx__destroy()/xxx__free() "destructors". So instead of fixing up > clean up code in selftests and user programs, handle such error pointers in > destructors themselves. This works beautifully for NULL pointers passed to > destructors, so might as well just work for error pointers. > > Suggested-by: Song Liu <songliubraving@fb.com> > Signed-off-by: Andrii Nakryiko <andriin@fb.com> Applied, thanks!
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index c9e760e120dc..ded5b29965f9 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -386,7 +386,7 @@ __s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name, void btf__free(struct btf *btf) { - if (!btf) + if (IS_ERR_OR_NULL(btf)) return; if (btf->fd >= 0) @@ -1025,7 +1025,7 @@ static int btf_ext_parse_hdr(__u8 *data, __u32 data_size) void btf_ext__free(struct btf_ext *btf_ext) { - if (!btf_ext) + if (IS_ERR_OR_NULL(btf_ext)) return; free(btf_ext->data); free(btf_ext); diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c index e1c344504cae..cf711168d34a 100644 --- a/tools/lib/bpf/btf_dump.c +++ b/tools/lib/bpf/btf_dump.c @@ -183,7 +183,7 @@ void btf_dump__free(struct btf_dump *d) { int i, cnt; - if (!d) + if (IS_ERR_OR_NULL(d)) return; free(d->type_states); diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 54830d603fee..b9f11f854985 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -6504,7 +6504,7 @@ void bpf_object__close(struct bpf_object *obj) { size_t i; - if (!obj) + if (IS_ERR_OR_NULL(obj)) return; if (obj->clear_priv) @@ -7690,7 +7690,7 @@ int bpf_link__destroy(struct bpf_link *link) { int err = 0; - if (!link) + if (IS_ERR_OR_NULL(link)) return 0; if (!link->disconnected && link->detach) @@ -8502,7 +8502,7 @@ void perf_buffer__free(struct perf_buffer *pb) { int i; - if (!pb) + if (IS_ERR_OR_NULL(pb)) return; if (pb->cpu_bufs) { for (i = 0; i < pb->cpu_cnt; i++) { @@ -9379,8 +9379,7 @@ void bpf_object__detach_skeleton(struct bpf_object_skeleton *s) for (i = 0; i < s->prog_cnt; i++) { struct bpf_link **link = s->progs[i].link; - if (!IS_ERR_OR_NULL(*link)) - bpf_link__destroy(*link); + bpf_link__destroy(*link); *link = NULL; } }
Most of libbpf "constructors" on failure return ERR_PTR(err) result encoded as a pointer. It's a common mistake to eventually pass such malformed pointers into xxx__destroy()/xxx__free() "destructors". So instead of fixing up clean up code in selftests and user programs, handle such error pointers in destructors themselves. This works beautifully for NULL pointers passed to destructors, so might as well just work for error pointers. Suggested-by: Song Liu <songliubraving@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> --- tools/lib/bpf/btf.c | 4 ++-- tools/lib/bpf/btf_dump.c | 2 +- tools/lib/bpf/libbpf.c | 9 ++++----- 3 files changed, 7 insertions(+), 8 deletions(-)