[PATCH v5 4/4] trace: change CPU ring buffer state from tracing_cpumask

From: Vaibhav Nagarnaik
Date: Thu Feb 02 2012 - 15:01:27 EST

According to Documentation/trace/ftrace.txt:


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.

Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@xxxxxxxxxx>
kernel/trace/trace.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index abf1108..e25672e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2592,10 +2592,12 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
if (cpumask_test_cpu(cpu, tracing_cpumask) &&
!cpumask_test_cpu(cpu, tracing_cpumask_new)) {
+ ring_buffer_record_disable_cpu(global_trace.buffer, cpu);
if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
cpumask_test_cpu(cpu, tracing_cpumask_new)) {
+ ring_buffer_record_enable_cpu(global_trace.buffer, cpu);

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