--- /dev/null
+From 71babb2705e2203a64c27ede13ae3508a0d2c16c Mon Sep 17 00:00:00 2001
+From: Vaibhav Nagarnaik <vnagarnaik@google.com>
+Date: Thu, 3 May 2012 18:59:52 -0700
+Subject: tracing: change CPU ring buffer state from tracing_cpumask
+
+From: Vaibhav Nagarnaik <vnagarnaik@google.com>
+
+commit 71babb2705e2203a64c27ede13ae3508a0d2c16c upstream.
+
+According to Documentation/trace/ftrace.txt:
+
+tracing_cpumask:
+
+ This is a mask that lets the user only trace
+ on specified CPUS. The format is a hex string
+ representing the CPUS.
+
+The tracing_cpumask currently doesn't affect the tracing state of
+per-CPU ring buffers.
+
+This patch enables/disables CPU recording as its corresponding bit in
+tracing_cpumask is set/unset.
+
+Link: http://lkml.kernel.org/r/1336096792-25373-3-git-send-email-vnagarnaik@google.com
+
+Cc: Frederic Weisbecker <fweisbec@gmail.com>
+Cc: Ingo Molnar <mingo@redhat.com>
+Cc: Laurent Chavey <chavey@google.com>
+Cc: Justin Teravest <teravest@google.com>
+Cc: David Sharp <dhsharp@google.com>
+Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
+Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ kernel/trace/trace.c | 2 ++
+ 1 file changed, 2 insertions(+)
+
+--- a/kernel/trace/trace.c
++++ b/kernel/trace/trace.c
+@@ -2432,10 +2432,12 @@ tracing_cpumask_write(struct file *filp,
+ if (cpumask_test_cpu(cpu, tracing_cpumask) &&
+ !cpumask_test_cpu(cpu, tracing_cpumask_new)) {
+ atomic_inc(&global_trace.data[cpu]->disabled);
++ ring_buffer_record_disable_cpu(global_trace.buffer, cpu);
+ }
+ if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
+ cpumask_test_cpu(cpu, tracing_cpumask_new)) {
+ atomic_dec(&global_trace.data[cpu]->disabled);
++ ring_buffer_record_enable_cpu(global_trace.buffer, cpu);
+ }
+ }
+ arch_spin_unlock(&ftrace_max_lock);