> On Jun 25, 2019, at 5:35 PM, Yonghong Song <yhs@xxxxxx> wrote:
>
> With CONFIG_MODULES=n, the following compiler warning occurs:
> /data/users/yhs/work/net-next/kernel/trace/bpf_trace.c:605:13: warning:
> ‘do_bpf_send_signal’ defined but not used [-Wunused-function]
> static void do_bpf_send_signal(struct irq_work *entry)
>
> The __init function send_signal_irq_work_init(), which calls
> do_bpf_send_signal(), is defined under CONFIG_MODULES. Hence,
> when CONFIG_MODULES=n, nobody calls static function do_bpf_send_signal(),
> hence the warning.
>
> The init function send_signal_irq_work_init() should work without
> CONFIG_MODULES. Moving it out of CONFIG_MODULES
> code section fixed the compiler warning, and also make bpf_send_signal()
> helper work without CONFIG_MODULES.
>
> Fixes: 8b401f9ed244 ("bpf: implement bpf_send_signal() helper")
> Reported-By: Arnd Bergmann <arnd@xxxxxxxx>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
Thanks for the fix!
Acked-by: Song Liu <songliubraving@xxxxxx>
> ---
> kernel/trace/bpf_trace.c | 27 ++++++++++++++-------------
> 1 file changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index c102c240bb0b..ca1255d14576 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1431,6 +1431,20 @@ int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
> return err;
> }
>
> +static int __init send_signal_irq_work_init(void)
> +{
> + int cpu;
> + struct send_signal_irq_work *work;
> +
> + for_each_possible_cpu(cpu) {
> + work = per_cpu_ptr(&send_signal_work, cpu);
> + init_irq_work(&work->irq_work, do_bpf_send_signal);
> + }
> + return 0;
> +}
> +
> +subsys_initcall(send_signal_irq_work_init);
> +
> #ifdef CONFIG_MODULES
> static int bpf_event_notify(struct notifier_block *nb, unsigned long op,
> void *module)
> @@ -1478,18 +1492,5 @@ static int __init bpf_event_init(void)
> return 0;
> }
>
> -static int __init send_signal_irq_work_init(void)
> -{
> - int cpu;
> - struct send_signal_irq_work *work;
> -
> - for_each_possible_cpu(cpu) {
> - work = per_cpu_ptr(&send_signal_work, cpu);
> - init_irq_work(&work->irq_work, do_bpf_send_signal);
> - }
> - return 0;
> -}
> -
> fs_initcall(bpf_event_init);
> -subsys_initcall(send_signal_irq_work_init);
> #endif /* CONFIG_MODULES */
> --
> 2.17.1
>
