tracing: change CPU ring buffer state from tracing_cpumask
Vaibhav Nagarnaik [Fri, 4 May 2012 01:59:52 +0000 (18:59 -0700)]
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

index 464a96f..5fc7bfa 100644 (file)
@@ -2648,10 +2648,12 @@ 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);