From: Andrii Nakryiko <andriin@fb.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>,
<daniel@iogearbox.net>
Cc: <andrii.nakryiko@gmail.com>, <kernel-team@fb.com>,
Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH bpf] libbpf: fix false uninitialized variable warning
Date: Wed, 25 Sep 2019 11:30:38 -0700 [thread overview]
Message-ID: <20190925183038.2755521-1-andriin@fb.com> (raw)
Some compilers emit warning for potential uninitialized next_id usage.
The code is correct, but control flow is too complicated for some
compilers to figure this out. Re-initialize next_id to satisfy
compiler.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
tools/lib/bpf/btf_dump.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 715967762312..84b0661db7f3 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -1140,60 +1140,61 @@ static void btf_dump_emit_type_chain(struct btf_dump *d,
case BTF_KIND_ARRAY: {
const struct btf_array *a = btf_array(t);
const struct btf_type *next_t;
__u32 next_id;
bool multidim;
/*
* GCC has a bug
* (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=8354)
* which causes it to emit extra const/volatile
* modifiers for an array, if array's element type has
* const/volatile modifiers. Clang doesn't do that.
* In general, it doesn't seem very meaningful to have
* a const/volatile modifier for array, so we are
* going to silently skip them here.
*/
while (decls->cnt) {
next_id = decls->ids[decls->cnt - 1];
next_t = btf__type_by_id(d->btf, next_id);
if (btf_is_mod(next_t))
decls->cnt--;
else
break;
}
if (decls->cnt == 0) {
btf_dump_emit_name(d, fname, last_was_ptr);
btf_dump_printf(d, "[%u]", a->nelems);
return;
}
+ next_id = decls->ids[decls->cnt - 1];
next_t = btf__type_by_id(d->btf, next_id);
multidim = btf_is_array(next_t);
/* we need space if we have named non-pointer */
if (fname[0] && !last_was_ptr)
btf_dump_printf(d, " ");
/* no parentheses for multi-dimensional array */
if (!multidim)
btf_dump_printf(d, "(");
btf_dump_emit_type_chain(d, decls, fname, lvl);
if (!multidim)
btf_dump_printf(d, ")");
btf_dump_printf(d, "[%u]", a->nelems);
return;
}
case BTF_KIND_FUNC_PROTO: {
const struct btf_param *p = btf_params(t);
__u16 vlen = btf_vlen(t);
int i;
btf_dump_emit_mods(d, decls);
if (decls->cnt) {
btf_dump_printf(d, " (");
btf_dump_emit_type_chain(d, decls, fname, lvl);
btf_dump_printf(d, ")");
} else {
btf_dump_emit_name(d, fname, last_was_ptr);
}
btf_dump_printf(d, "(");
/*
* Clang for BPF target generates func_proto with no
--
2.17.1
next reply other threads:[~2019-09-25 18:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 18:30 Andrii Nakryiko [this message]
2019-09-25 20:27 ` [PATCH bpf] libbpf: fix false uninitialized variable warning Daniel Borkmann
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