ring-buffer: Do not disable recording when there is an iterator

Now that the iterator can handle a concurrent writer, do not disable writing
to the ring buffer when there is an iterator present.

Link: http://lkml.kernel.org/r/20200317213416.759770696@goodmis.orgSigned-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/ring_buffer.c

@@ -4312,7 +4312,6 @@ ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags)
 	iter->cpu_buffer = cpu_buffer;
 
 	atomic_inc(&cpu_buffer->resize_disabled);
-	atomic_inc(&cpu_buffer->record_disabled);
 
 	return iter;
 }
@@ -4385,7 +4384,6 @@ ring_buffer_read_finish(struct ring_buffer_iter *iter)
 	rb_check_pages(cpu_buffer);
 	raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
 
-	atomic_dec(&cpu_buffer->record_disabled);
 	atomic_dec(&cpu_buffer->resize_disabled);
 	kfree(iter->event);
 	kfree(iter);