| Message ID | 20200430021436.1522502-1-andriin@fb.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [v2,bpf-next] libbpf: fix false uninitialized variable warning | expand |
On Thu, Apr 30, 2020 at 04:14 AM CEST, Andrii Nakryiko wrote: > Some versions of GCC falsely detect that vi might not be initialized. That's > not true, but let's silence it with NULL initialization. > > Signed-off-by: Andrii Nakryiko <andriin@fb.com> > --- > tools/lib/bpf/libbpf.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index d86ff8214b96..977add1b73e2 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -5003,8 +5003,8 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj, > GElf_Shdr *shdr, Elf_Data *data) > { > int i, j, nrels, new_sz, ptr_sz = sizeof(void *); > + const struct btf_var_secinfo *vi = NULL; > const struct btf_type *sec, *var, *def; > - const struct btf_var_secinfo *vi; > const struct btf_member *member; > struct bpf_map *map, *targ_map; > const char *name, *mname; Alternatively we could borrow the kernel uninitialized_var macro: include/linux/compiler-clang.h:#define uninitialized_var(x) x = *(&(x)) include/linux/compiler-gcc.h:#define uninitialized_var(x) x = x
On 4/30/20 10:13 AM, Jakub Sitnicki wrote: > On Thu, Apr 30, 2020 at 04:14 AM CEST, Andrii Nakryiko wrote: >> Some versions of GCC falsely detect that vi might not be initialized. That's >> not true, but let's silence it with NULL initialization. >> >> Signed-off-by: Andrii Nakryiko <andriin@fb.com> >> --- >> tools/lib/bpf/libbpf.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c >> index d86ff8214b96..977add1b73e2 100644 >> --- a/tools/lib/bpf/libbpf.c >> +++ b/tools/lib/bpf/libbpf.c >> @@ -5003,8 +5003,8 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj, >> GElf_Shdr *shdr, Elf_Data *data) >> { >> int i, j, nrels, new_sz, ptr_sz = sizeof(void *); >> + const struct btf_var_secinfo *vi = NULL; >> const struct btf_type *sec, *var, *def; >> - const struct btf_var_secinfo *vi; >> const struct btf_member *member; >> struct bpf_map *map, *targ_map; >> const char *name, *mname; > > Alternatively we could borrow the kernel uninitialized_var macro: > > include/linux/compiler-clang.h:#define uninitialized_var(x) x = *(&(x)) > include/linux/compiler-gcc.h:#define uninitialized_var(x) x = x We could do that potentially, at least to mark such locations explicitly, although I wonder if it's not more churn than anything else adding the infra for it. But generally no objections from my side. Anyway, applied this one, thanks!
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index d86ff8214b96..977add1b73e2 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -5003,8 +5003,8 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data *data) { int i, j, nrels, new_sz, ptr_sz = sizeof(void *); + const struct btf_var_secinfo *vi = NULL; const struct btf_type *sec, *var, *def; - const struct btf_var_secinfo *vi; const struct btf_member *member; struct bpf_map *map, *targ_map; const char *name, *mname;
Some versions of GCC falsely detect that vi might not be initialized. That's not true, but let's silence it with NULL initialization. Signed-off-by: Andrii Nakryiko <andriin@fb.com> --- tools/lib/bpf/libbpf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)