ring-buffer: Do not poll non allocated cpu buffers

The tracing infrastructure sets up for possible CPUs, but it uses
the ring buffer polling, it is possible to call the ring buffer
polling code with a CPU that hasn't been allocated. This will cause
a kernel oops when it access a ring buffer cpu buffer that is part
of the possible cpus but hasn't been allocated yet as the CPU has never
been online.

Reported-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2013-05-23 14:21:36 -04:00 коммит произвёл Steven Rostedt
Родитель ca1643186d
Коммит 6721cb6002
1 изменённых файлов: 3 добавлений и 0 удалений

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@ -620,6 +620,9 @@ int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
if (cpu == RING_BUFFER_ALL_CPUS)
work = &buffer->irq_work;
else {
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return -EINVAL;
cpu_buffer = buffer->buffers[cpu];
work = &cpu_buffer->irq_work;
}