On 7/27/23 4:01 AM, Jiri Olsa wrote:
On Thu, Jul 27, 2023 at 04:25:36PM +0800, Xiangyu Chen wrote:
From: Xiangyu Chen <xiangyu.chen@xxxxxxxxxxxxx>
When turn on the yocto DEBUG_BUILD flag, the build options for gcc would enable maybe-uninitialized,
and following warnings would be reported as below:
curious, what's the gcc version? I can't reproduce that,
and we already have all warnings enabled:
CFLAGS += -Werror -Wall
they seem like false warnings also, because ARRAY_SIZE(pads)
will be always > 0
Agree. This definitely a false positive.
In kernel top Makefile, we have
# Enabled with W=2, disabled by default as noisy
ifdef CONFIG_CC_IS_GCC
KBUILD_CFLAGS += -Wno-maybe-uninitialized
endif
That means gcc -maybe-uninitialized is very noisy.
jirka
| btf_dump.c: In function 'btf_dump_emit_bit_padding':
| btf_dump.c:916:4: error: 'pad_type' may be used uninitialized in this function [-Werror=maybe-uninitialized]
| 916 | btf_dump_printf(d, "\n%s%s: %d;", pfx(lvl), pad_type,
| | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| 917 | in_bitfield ? new_off - cur_off : 0);
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| btf_dump.c:929:6: error: 'pad_bits' may be used uninitialized in this function [-Werror=maybe-uninitialized]
| 929 | if (bits == pad_bits) {
| | ^
| btf_dump.c:913:28: error: 'new_off' may be used uninitialized in this function [-Werror=maybe-uninitialized]
| 913 | (new_off == next_off && roundup(cur_off, next_align * 8) != new_off) ||
| | ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| HOSTLD scripts/mod/modpost
Signed-off-by: Xiangyu Chen <xiangyu.chen@xxxxxxxxxxxxx>
---
tools/lib/bpf/btf_dump.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 4d9f30bf7f01..79923c3b8777 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -867,8 +867,8 @@ static void btf_dump_emit_bit_padding(const struct btf_dump *d,
} pads[] = {
{"long", d->ptr_sz * 8}, {"int", 32}, {"short", 16}, {"char", 8}
};
- int new_off, pad_bits, bits, i;
- const char *pad_type;
+ int new_off = 0, pad_bits = 0, bits, i;
+ const char *pad_type = NULL;
if (cur_off >= next_off)
return; /* no gap */
--
2.34.1
