ring-buffer: remove unnecessary cpu_relax

The loops in the ring buffer that use cpu_relax are not dependent on
other CPUs. They simply came across some padding in the ring buffer and
are skipping over them. It is a normal loop and does not require a
cpu_relax.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 2878bd4..a05541a 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -3132,10 +3132,8 @@ ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
                spin_unlock(&cpu_buffer->reader_lock);
        local_irq_restore(flags);
 
-       if (event && event->type_len == RINGBUF_TYPE_PADDING) {
-               cpu_relax();
+       if (event && event->type_len == RINGBUF_TYPE_PADDING)
                goto again;
-       }
 
        return event;
 }
@@ -3160,10 +3158,8 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
        event = rb_iter_peek(iter, ts);
        spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
 
-       if (event && event->type_len == RINGBUF_TYPE_PADDING) {
-               cpu_relax();
+       if (event && event->type_len == RINGBUF_TYPE_PADDING)
                goto again;
-       }
 
        return event;
 }
@@ -3209,10 +3205,8 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts)
  out:
        preempt_enable();
 
-       if (event && event->type_len == RINGBUF_TYPE_PADDING) {
-               cpu_relax();
+       if (event && event->type_len == RINGBUF_TYPE_PADDING)
                goto again;
-       }
 
        return event;
 }
@@ -3302,10 +3296,8 @@ ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts)
  out:
        spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
 
-       if (event && event->type_len == RINGBUF_TYPE_PADDING) {
-               cpu_relax();
+       if (event && event->type_len == RINGBUF_TYPE_PADDING)
                goto again;
-       }
 
        return event;
 }