On Mon, Apr 17, 2023 at 03:47:36PM +0000, Yafang Shao wrote:
> diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
> index f61d513..3df39a5 100644
> --- a/kernel/bpf/trampoline.c
> +++ b/kernel/bpf/trampoline.c
> @@ -842,15 +842,21 @@ static __always_inline u64 notrace bpf_prog_start_time(void)
> static u64 notrace __bpf_prog_enter_recur(struct bpf_prog *prog, struct bpf_tramp_run_ctx *run_ctx)
> __acquires(RCU)
> {
> - rcu_read_lock();
> - migrate_disable();
> -
> - run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx);
> + int bit;
>
> - if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) {
> + rcu_read_lock();
> + bit = test_recursion_try_acquire(_THIS_IP_, _RET_IP_);
and bpf will prevent ftrace to run and vice versa.
Not a good idea.
One bpf prog will prevent different bpf prog to run since they share current task.
Not a good idea either.
