| Message ID | 20190205194822.1804874-1-yhs@fb.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | tools/bpf: two changes in libbpf | expand |
On Tue, Feb 05, 2019 at 11:48:22AM -0800, Yonghong Song wrote: > Commit 96408c43447a ("tools/bpf: implement libbpf btf__get_map_kv_tids() API function") > added the API function btf__get_map_kv_tids(): > btf__get_map_kv_tids(const struct btf *btf, char *map_name, ...) > > The parameter map_name has type "char *". This is okay inside libbpf library since > the map_name is from bpf_map->name which also has type "char *". > > This will be problematic if the caller for map_name already has attribute "const", > e.g., from C++ string.c_str(). It will result in either a warning or an error. > > /home/yhs/work/bcc/src/cc/btf.cc:166:51: > error: invalid conversion from ‘const char*’ to ‘char*’ [-fpermissive] > return btf__get_map_kv_tids(btf_, map_name.c_str() > > This patch added "const" attributes to map_name parameter. > > Fixes: 96408c43447a ("tools/bpf: implement libbpf btf__get_map_kv_tids() API function") > Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org>
On Tue, Feb 5, 2019 at 6:27 PM Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote: > > On Tue, Feb 05, 2019 at 11:48:22AM -0800, Yonghong Song wrote: > > Commit 96408c43447a ("tools/bpf: implement libbpf btf__get_map_kv_tids() API function") > > added the API function btf__get_map_kv_tids(): > > btf__get_map_kv_tids(const struct btf *btf, char *map_name, ...) > > > > The parameter map_name has type "char *". This is okay inside libbpf library since > > the map_name is from bpf_map->name which also has type "char *". > > > > This will be problematic if the caller for map_name already has attribute "const", > > e.g., from C++ string.c_str(). It will result in either a warning or an error. > > > > /home/yhs/work/bcc/src/cc/btf.cc:166:51: > > error: invalid conversion from ‘const char*’ to ‘char*’ [-fpermissive] > > return btf__get_map_kv_tids(btf_, map_name.c_str() > > > > This patch added "const" attributes to map_name parameter. > > > > Fixes: 96408c43447a ("tools/bpf: implement libbpf btf__get_map_kv_tids() API function") > > Signed-off-by: Yonghong Song <yhs@fb.com> > > Acked-by: Alexei Starovoitov <ast@kernel.org> Actually just applied this patch alone, since it's independent from 2nd.
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 4949f8840bda..3b3a2959d03a 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -511,7 +511,7 @@ int btf__get_from_id(__u32 id, struct btf **btf) return err; } -int btf__get_map_kv_tids(const struct btf *btf, char *map_name, +int btf__get_map_kv_tids(const struct btf *btf, const char *map_name, __u32 expected_key_size, __u32 expected_value_size, __u32 *key_type_id, __u32 *value_type_id) { diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index 25a9d2db035d..b393da90cc85 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -69,7 +69,7 @@ LIBBPF_API void btf__get_strings(const struct btf *btf, const char **strings, __u32 *str_len); LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset); LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf); -LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, char *map_name, +LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name, __u32 expected_key_size, __u32 expected_value_size, __u32 *key_type_id, __u32 *value_type_id);
Commit 96408c43447a ("tools/bpf: implement libbpf btf__get_map_kv_tids() API function") added the API function btf__get_map_kv_tids(): btf__get_map_kv_tids(const struct btf *btf, char *map_name, ...) The parameter map_name has type "char *". This is okay inside libbpf library since the map_name is from bpf_map->name which also has type "char *". This will be problematic if the caller for map_name already has attribute "const", e.g., from C++ string.c_str(). It will result in either a warning or an error. /home/yhs/work/bcc/src/cc/btf.cc:166:51: error: invalid conversion from ‘const char*’ to ‘char*’ [-fpermissive] return btf__get_map_kv_tids(btf_, map_name.c_str() This patch added "const" attributes to map_name parameter. Fixes: 96408c43447a ("tools/bpf: implement libbpf btf__get_map_kv_tids() API function") Signed-off-by: Yonghong Song <yhs@fb.com> --- tools/lib/bpf/btf.c | 2 +- tools/lib/bpf/btf.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)