ring-buffer: Add stats field for amount read from trace ring buffer

[deliverable/linux.git] / kernel / trace / ring_buffer.c

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 13950d9027cb901dc3f11c5e243a85fb972b507f..7244acde77b0a9a5670d401fc505c64c5d8b06c0 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -3102,6 +3102,24 @@ ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu)
 }
 EXPORT_SYMBOL_GPL(ring_buffer_dropped_events_cpu);
 
+/**
+ * ring_buffer_read_events_cpu - get the number of events successfully read
+ * @buffer: The ring buffer
+ * @cpu: The per CPU buffer to get the number of events read
+ */
+unsigned long
+ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu)
+{
+       struct ring_buffer_per_cpu *cpu_buffer;
+
+       if (!cpumask_test_cpu(cpu, buffer->cpumask))
+               return 0;
+
+       cpu_buffer = buffer->buffers[cpu];
+       return cpu_buffer->read;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_read_events_cpu);
+
 /**
  * ring_buffer_entries - get the number of entries in a buffer
  * @buffer: The ring buffer