From: Arnd Bergmann Some internal functions in bpf produce a warning when -Wsuggest-attribute=format is passed to the compiler, e.g. in 'make W=1': kernel/trace/bpf_trace.c: In function '____bpf_trace_printk': kernel/trace/bpf_trace.c:377:9: error: function '____bpf_trace_printk' might be a candidate for 'gnu_printf' format attribute [-Werror=suggest-attribute=format] 377 | ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt, data.bin_args); | ^~~ The attribute here is useless since there are no callers from C code, but it helps to shut up the output anyway so we can eventually turn the warning option on by default. Signed-off-by: Arnd Bergmann --- kernel/bpf/helpers.c | 1 + kernel/bpf/stream.c | 1 + kernel/trace/bpf_trace.c | 3 +++ 3 files changed, 5 insertions(+) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index b54ec0e945aa..45d026fc4e8a 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1046,6 +1046,7 @@ int bpf_bprintf_prepare(const char *fmt, u32 fmt_size, const u64 *raw_args, return err; } +__printf(3, 0) BPF_CALL_5(bpf_snprintf, char *, str, u32, str_size, char *, fmt, const void *, args, u32, data_len) { diff --git a/kernel/bpf/stream.c b/kernel/bpf/stream.c index 24730df55e69..816fd7fba3d2 100644 --- a/kernel/bpf/stream.c +++ b/kernel/bpf/stream.c @@ -212,6 +212,7 @@ __bpf_kfunc_start_defs(); * Avoid using enum bpf_stream_id so that kfunc users don't have to pull in the * enum in headers. */ +__printf(2, 0) __bpf_kfunc int bpf_stream_vprintk(int stream_id, const char *fmt__str, const void *args, u32 len__sz, struct bpf_prog_aux *aux) { diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index eadaef8592a3..2d3de71ab86a 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -359,6 +359,7 @@ static const struct bpf_func_proto bpf_probe_write_user_proto = { #define MAX_TRACE_PRINTK_VARARGS 3 #define BPF_TRACE_PRINTK_SIZE 1024 +__printf(1, 0) BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, u64, arg2, u64, arg3) { @@ -412,6 +413,7 @@ const struct bpf_func_proto *bpf_get_trace_printk_proto(void) return &bpf_trace_printk_proto; } +__printf(1, 0) BPF_CALL_4(bpf_trace_vprintk, char *, fmt, u32, fmt_size, const void *, args, u32, data_len) { @@ -455,6 +457,7 @@ const struct bpf_func_proto *bpf_get_trace_vprintk_proto(void) return &bpf_trace_vprintk_proto; } +__printf(2, 0) BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size, const void *, args, u32, data_len) { -- 2.39.5