1 files changed, 9 insertions, 8 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 75f1d05ea82d..9c6045a27ba3 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1887,12 +1887,6 @@ rb_event_index(struct ring_buffer_event *event)
         return (addr & ~PAGE_MASK) - BUF_PAGE_HDR_SIZE;
 }
 
-static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
-{
-        cpu_buffer->read_stamp = cpu_buffer->reader_page->page->time_stamp;
-        cpu_buffer->reader_page->read = 0;
-}
-
 static void rb_inc_iter(struct ring_buffer_iter *iter)
 {
         struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer;
@@ -2803,8 +2797,11 @@ rb_reserve_next_event(struct ring_buffer *buffer,
 
         event = __rb_reserve_next(cpu_buffer, &info);
 
-        if (unlikely(PTR_ERR(event) == -EAGAIN))
+        if (unlikely(PTR_ERR(event) == -EAGAIN)) {
+                if (info.add_timestamp)
+                        info.length -= RB_LEN_TIME_EXTEND;
                 goto again;
+        }
 
         if (!event)
                 goto out_fail;
@@ -3626,7 +3623,7 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
 
         /* Finally update the reader page to the new head */
         cpu_buffer->reader_page = reader;
-        rb_reset_reader_page(cpu_buffer);
+        cpu_buffer->reader_page->read = 0;
 
         if (overwrite != cpu_buffer->last_overrun) {
                 cpu_buffer->lost_events = overwrite - cpu_buffer->last_overrun;
@@ -3636,6 +3633,10 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
         goto again;
 
  out:
+        /* Update the read_stamp on the first event */
+        if (reader && reader->read == 0)
+                cpu_buffer->read_stamp = reader->page->time_stamp;
+
         arch_spin_unlock(&cpu_buffer->lock);
         local_irq_restore(flags);