unsigned long ring_buffer_entries(struct ring_buffer *buffer);
unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
unsigned long ring_buffer_entries(struct ring_buffer *buffer);
unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);