Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[pandora-kernel.git] / kernel / trace / ring_buffer.c

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 7f6059c..1da7b6e 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1768,6 +1768,14 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer,
         * must fill the old tail_page with padding.
         */
        if (tail >= BUF_PAGE_SIZE) {
+               /*
+                * If the page was filled, then we still need
+                * to update the real_end. Reset it to zero
+                * and the reader will ignore it.
+                */
+               if (tail == BUF_PAGE_SIZE)
+                       tail_page->real_end = 0;
+
                local_sub(length, &tail_page->write);
                return;
        }
@@ -3894,12 +3902,12 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
        ret = read;
 
        cpu_buffer->lost_events = 0;
+
+       commit = local_read(&bpage->commit);
        /*
         * Set a flag in the commit field if we lost events
         */
        if (missed_events) {
-               commit = local_read(&bpage->commit);
-
                /* If there is room at the end of the page to save the
                 * missed events, then record it there.
                 */
@@ -3907,10 +3915,17 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
                        memcpy(&bpage->data[commit], &missed_events,
                               sizeof(missed_events));
                        local_add(RB_MISSED_STORED, &bpage->commit);
+                       commit += sizeof(missed_events);
                }
                local_add(RB_MISSED_EVENTS, &bpage->commit);
        }
 
+       /*
+        * This page may be off to user land. Zero it out here.
+        */
+       if (commit < BUF_PAGE_SIZE)
+               memset(&bpage->data[commit], 0, BUF_PAGE_SIZE - commit);
+
  out_unlock:
        spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);