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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>
hifive-unleashed-5.1
Steven Rostedt (Red Hat) 2013-05-23 14:21:36 -04:00 committed by Steven Rostedt
parent ca1643186d
commit 6721cb6002
1 changed files with 3 additions and 0 deletions
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3
kernel/trace/ring_buffer.c
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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;
}