On Tue, Dec 9, 2025 at 10:37 PM Andy Shevchenko <[email protected]> wrote: > > On Tue, Dec 09, 2025 at 06:12:46PM +0900, Alexei Starovoitov wrote: > > On Tue, Dec 9, 2025 at 1:21 AM Andy Shevchenko > > <[email protected]> wrote: > > > > > > The printing functions in BPF code are using printf() type of format, > > > and compiler is not happy about them as is: > > > > > > kernel/bpf/helpers.c:1069:9: error: function ‘____bpf_snprintf’ might be > > > a candidate for ‘gnu_printf’ format attribute > > > [-Werror=suggest-attribute=format] > > > 1069 | err = bstr_printf(str, str_size, fmt, data.bin_args); > > > | ^~~ > > > > > > 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); > > > | ^~~ > > > > > > kernel/trace/bpf_trace.c:433:9: error: function ‘____bpf_trace_vprintk’ > > > might be a candidate for ‘gnu_printf’ format attribute > > > [-Werror=suggest-attribute=format] > > > 433 | ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt, > > > data.bin_args); > > > | ^~~ > > > > > > kernel/trace/bpf_trace.c:475:9: error: function ‘____bpf_seq_printf’ > > > might be a candidate for ‘gnu_printf’ format attribute > > > [-Werror=suggest-attribute=format] > > > 475 | seq_bprintf(m, fmt, data.bin_args); > > > | ^~~~~~~~~~~ > > > > > > Fix the compilation errors by adding __printf() attribute. For that > > > we need to pass it down to the BPF_CALL_x() and wrap into > > > PRINTF_BPF_CALL_*() > > > to make code neater. > > > This is pointless churn to shut up a warning. > > In some cases, like mine, it's an error. > > > Teach syzbot to stop this spam instead. > > It prevents to perform `make W=1` builds with the default CONFIG_WERROR, > which is 'y'. > > > At the end this patch doesn't make any visible difference, > > since user declarations of these helpers are auto generated > > from uapi/bpf.h file and __printf attribute is not there. > > I see, thanks for the review. > Any recommendations on how to fix this properly?
Add -Wno-suggest-attribute=format to corresponding files in Makefile. I think it's cleaner than __diag_ignore() in the .c
