| Message ID | 20200831000304.1696435-1-Tony.Ambardar@gmail.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf,v1] libbpf: fix build failure from uninitialized variable warning | expand |
On 8/31/20 2:03 AM, Tony Ambardar wrote: > While compiling libbpf, some GCC versions (at least 8.4.0) have difficulty > determining control flow and a emit warning for potentially uninitialized > usage of 'map', which results in a build error if using "-Werror": > > In file included from libbpf.c:56: > libbpf.c: In function '__bpf_object__open': > libbpf_internal.h:59:2: warning: 'map' may be used uninitialized in this function [-Wmaybe-uninitialized] > libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__); \ > ^~~~~~~~~~~~ > libbpf.c:5032:18: note: 'map' was declared here > struct bpf_map *map, *targ_map; > ^~~ > > The warning/error is false based on code inspection, so silence it with a > NULL initialization. > > Fixes: 646f02ffdd49 ("libbpf: Add BTF-defined map-in-map support") > Ref: 063e68813391 ("libbpf: Fix false uninitialized variable warning") > > Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com> Applied, thanks!
On Mon, 31 Aug 2020 at 07:59, Daniel Borkmann <daniel@iogearbox.net> wrote: > > On 8/31/20 2:03 AM, Tony Ambardar wrote: > > While compiling libbpf, some GCC versions (at least 8.4.0) have difficulty > > determining control flow and a emit warning for potentially uninitialized > > usage of 'map', which results in a build error if using "-Werror": > > > > In file included from libbpf.c:56: > > libbpf.c: In function '__bpf_object__open': > > libbpf_internal.h:59:2: warning: 'map' may be used uninitialized in this function [-Wmaybe-uninitialized] > > libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__); \ > > ^~~~~~~~~~~~ > > libbpf.c:5032:18: note: 'map' was declared here > > struct bpf_map *map, *targ_map; > > ^~~ > > > > The warning/error is false based on code inspection, so silence it with a > > NULL initialization. > > > > Fixes: 646f02ffdd49 ("libbpf: Add BTF-defined map-in-map support") > > Ref: 063e68813391 ("libbpf: Fix false uninitialized variable warning") > > > > Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com> > > Applied, thanks! Thanks, Daniel. I forgot to ask/confirm whether this will get applied to the 5.8.x stable branch, since it was first encountered there.
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index b688aadf09c5..46d727b45c81 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -5804,8 +5804,8 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj, int i, j, nrels, new_sz; const struct btf_var_secinfo *vi = NULL; const struct btf_type *sec, *var, *def; + struct bpf_map *map = NULL, *targ_map; const struct btf_member *member; - struct bpf_map *map, *targ_map; const char *name, *mname; Elf_Data *symbols; unsigned int moff;
While compiling libbpf, some GCC versions (at least 8.4.0) have difficulty determining control flow and a emit warning for potentially uninitialized usage of 'map', which results in a build error if using "-Werror": In file included from libbpf.c:56: libbpf.c: In function '__bpf_object__open': libbpf_internal.h:59:2: warning: 'map' may be used uninitialized in this function [-Wmaybe-uninitialized] libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__); \ ^~~~~~~~~~~~ libbpf.c:5032:18: note: 'map' was declared here struct bpf_map *map, *targ_map; ^~~ The warning/error is false based on code inspection, so silence it with a NULL initialization. Fixes: 646f02ffdd49 ("libbpf: Add BTF-defined map-in-map support") Ref: 063e68813391 ("libbpf: Fix false uninitialized variable warning") Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com> --- tools/lib/bpf/libbpf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)