Merge branch 'for-rmk/perf' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux into devel-stable

  * Support for Qualcomm Krait processors (run perf on your phone!)
  * Support for Cortex-A12 (run perf stat on your FPGA!)
  * Support for perf_sample_event_took, allowing us to automatically decrease
    the sample rate if we can't handle the PMU interrupts quickly enough
    (run perf record on your FPGA!).

As part of the Krait support, we also gain support for PPI generation by
the PMU.

1 files changed, 7 insertions, 0 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 294b8a271a04..fc4da2d97f9b 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2397,6 +2397,13 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
         write &= RB_WRITE_MASK;
         tail = write - length;
 
+        /*
+         * If this is the first commit on the page, then it has the same
+         * timestamp as the page itself.
+         */
+        if (!tail)
+                delta = 0;
+
         /* See if we shot pass the end of this buffer page */
         if (unlikely(write > BUF_PAGE_SIZE))
                 return rb_move_tail(cpu_buffer, length, tail,