tracing: change CPU ring buffer state from tracing_cpumask

BugLink: http://bugs.launchpad.net/bugs/1025406

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>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0731e81a5bb..672a749dbba 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2432,10 +2432,12 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
                 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);