ring-buffer: Fix accounting of entries when removing pages

When removing pages from the ring buffer, its state is not reset. This
means that the counters need to be correctly updated to account for the
pages removed.

Update the overrun counter to reflect the removed events from the pages.

Link: http://lkml.kernel.org/r/1340998301-1715-1-git-send-email-vnagarnaik@google.com
Cc: Justin Teravest <teravest@google.com>
Cc: David Sharp <dhsharp@google.com>
Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index ba39cbabdc9fe6f1b94a19047ee994c9f1a511fa..f765465bffe47968752e272308d7fb5b63093a65 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1347,10 +1347,9 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned int nr_pages)
                         * If something was added to this page, it was full
                         * since it is not the tail page. So we deduct the
                         * bytes consumed in ring buffer from here.
-                        * No need to update overruns, since this page is
-                        * deleted from ring buffer and its entries are
-                        * already accounted for.
+                        * Increment overrun to account for the lost events.
                         */
+                       local_add(page_entries, &cpu_buffer->overrun);
                        local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes);
                }