As reported by Mirsad [1] we still see format warnings in kernel/bpf/btf.o
at W=1 warning level:
CC kernel/bpf/btf.o
./kernel/bpf/btf.c: In function ‘btf_type_seq_show_flags’:
./kernel/bpf/btf.c:7553:21: warning: assignment left-hand side might be a candidate for a format attribute [-Wsuggest-attribute=format]
7553 | sseq.showfn = btf_seq_show;
| ^
./kernel/bpf/btf.c: In function ‘btf_type_snprintf_show’:
./kernel/bpf/btf.c:7604:31: warning: assignment left-hand side might be a candidate for a format attribute [-Wsuggest-attribute=format]
7604 | ssnprintf.show.showfn = btf_snprintf_show;
| ^
Combined with CONFIG_WERROR=y these can halt the build.
The fix (annotating the structure field with __printf())
suggested by Mirsad resolves these. Apologies I missed this last time.
No other W=1 warnings were observed in kernel/bpf after this fix.
[1] https://lore.kernel.org/bpf/92c9d047-f058-400c-9c7d-81d4dc1ef71b@xxxxxxxxx/
Fixes: b3470da314fd ("bpf: annotate BTF show functions with __printf")
Suggested-by: Mirsad Todorovac <mtodorovac69@xxxxxxxxx>
Reported-by: Mirsad Todorovac <mtodorovac69@xxxxxxxxx>
Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
---
kernel/bpf/btf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index d5019c4454d6..520f49f422fe 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -415,7 +415,7 @@ const char *btf_type_str(const struct btf_type *t)
struct btf_show {
u64 flags;
void *target; /* target of show operation (seq file, buffer) */
- void (*showfn)(struct btf_show *show, const char *fmt, va_list args);
+ __printf(2, 0) void (*showfn)(struct btf_show *show, const char *fmt, va_list args);
const struct btf *btf;
/* below are used during iteration */
struct {
--
2.31.1
