From: Vaibhav Nagarnaik <vnagarnaik@google.com>
Date: Wed, 10 Oct 2012 23:40:27 +0000 (-0700)
Subject: ring-buffer: Check for uninitialized cpu buffer before resizing
X-Git-Tag: v3.7-rc3~40^2^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8e49f418c9632790bf456634742d34d97120a784;p=pandora-kernel.git

ring-buffer: Check for uninitialized cpu buffer before resizing

With a system where, num_present_cpus < num_possible_cpus, even if all
CPUs are online, non-present CPUs don't have per_cpu buffers allocated.
If per_cpu/<cpu>/buffer_size_kb is modified for such a CPU, it can cause
a panic due to NULL dereference in ring_buffer_resize().

To fix this, resize operation is allowed only if the per-cpu buffer has
been initialized.

Link: http://lkml.kernel.org/r/1349912427-6486-1-git-send-email-vnagarnaik@google.com

Cc: stable@vger.kernel.org # 3.5+
Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---

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