This is a note to let you know that I've just added the patch titled
bpftool: Print newline before '}' for struct with padding only fields
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpftool-print-newline-before-for-struct-with-padding.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 55884de95fc21bea9190fff34e03e1144adc53f5
Author: Eduard Zingerman <eddyz87@xxxxxxxxx>
Date: Sat Oct 1 13:44:24 2022 +0300
bpftool: Print newline before '}' for struct with padding only fields
[ Upstream commit 44a726c3f23cf762ef4ce3c1709aefbcbe97f62c ]
btf_dump_emit_struct_def attempts to print empty structures at a
single line, e.g. `struct empty {}`. However, it has to account for a
case when there are no regular but some padding fields in the struct.
In such case `vlen` would be zero, but size would be non-zero.
E.g. here is struct bpf_timer from vmlinux.h before this patch:
struct bpf_timer {
long: 64;
long: 64;};
And after this patch:
struct bpf_dynptr {
long: 64;
long: 64;
};
Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20221001104425.415768-1-eddyz87@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 558d34fbd331c..6a8d8ed34b760 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -969,7 +969,11 @@ static void btf_dump_emit_struct_def(struct btf_dump *d,
if (is_struct)
btf_dump_emit_bit_padding(d, off, t->size * 8, align, false, lvl + 1);
- if (vlen)
+ /*
+ * Keep `struct empty {}` on a single line,
+ * only print newline when there are regular or padding fields.
+ */
+ if (vlen || t->size)
btf_dump_printf(d, "\n");
btf_dump_printf(d, "%s}", pfx(lvl));
if (packed)
