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tracing: change CPU ring buffer state from tracing_cpumask

commit 71babb2 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: Ben Hutchings <ben@decadent.org.uk>
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1 parent 7d124dd commit 907e461a4f50ca31c36575b03c14d2c07ba20df0 @vnagarnaik vnagarnaik committed with bwhacks May 3, 2012
Showing with 2 additions and 0 deletions.
  1. +2 −0 kernel/trace/trace.c
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2 kernel/trace/trace.c
@@ -2541,10 +2541,12 @@ 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);

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