On Mon, Oct 30, 2017 at 01:50:22PM -0700, Yonghong Song wrote:
> Could you check whether the below change to remove rcu_dereference_protected
> is what you wanted or not?
Yep that looks fine. Thanks!
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index b65011d..e7685c5 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -767,20 +767,19 @@ int perf_event_attach_bpf_prog(struct perf_event *event,
> mutex_lock(&bpf_event_mutex);
>
> if (event->prog)
> - goto out;
> + goto unlock;
>
> - old_array = rcu_dereference_protected(event->tp_event->prog_array,
> -
> lockdep_is_held(&bpf_event_mutex));
> + old_array = event->tp_event->prog_array;
> ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
> if (ret < 0)
> - goto out;
> + goto unlock;
>
> /* set the new array to event->tp_event and set event->prog */
> event->prog = prog;
> rcu_assign_pointer(event->tp_event->prog_array, new_array);
> bpf_prog_array_free(old_array);
>
> -out:
> +unlock:
> mutex_unlock(&bpf_event_mutex);
> return ret;
> }
> @@ -794,11 +793,9 @@ void perf_event_detach_bpf_prog(struct perf_event *event)
> mutex_lock(&bpf_event_mutex);
>
> if (!event->prog)
> - goto out;
> -
> - old_array = rcu_dereference_protected(event->tp_event->prog_array,
> -
> lockdep_is_held(&bpf_event_mutex));
> + goto unlock;
>
> + old_array = event->tp_event->prog_array;
> ret = bpf_prog_array_copy(old_array, event->prog, NULL, &new_array);
> if (ret < 0) {
> bpf_prog_array_delete_safe(old_array, event->prog);
> @@ -810,6 +807,6 @@ void perf_event_detach_bpf_prog(struct perf_event *event)
> bpf_prog_put(event->prog);
> event->prog = NULL;
>
> -out:
> +unlock:
> mutex_unlock(&bpf_event_mutex);
> }
> --
> 2.9.5
>
