tracing: Use swap macro in update_max_tr

Make use of the swap macro and remove unnecessary variable _buf_.
This makes the code easier to read and maintain. Also, reduces the
stack usage.

This code was detected with the help of Coccinelle.

Link: http://lkml.kernel.org/r/20180209175316.GA18720@embeddedgus
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c9336e9..a0079b4 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1360,8 +1360,6 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 void
 update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 {
-       struct ring_buffer *buf;
-
        if (tr->stop_count)
                return;
 
@@ -1375,9 +1373,7 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 
        arch_spin_lock(&tr->max_lock);
 
-       buf = tr->trace_buffer.buffer;
-       tr->trace_buffer.buffer = tr->max_buffer.buffer;
-       tr->max_buffer.buffer = buf;
+       swap(tr->trace_buffer.buffer, tr->max_buffer.buffer);
 
        __update_max_tr(tr, tsk, cpu);
        arch_spin_unlock(&tr->max_lock);