tree 6cc9ddc8b6a830be7f7ae72394774d3d9c506889
parent 3c0cccf93df4855ebab815e133e8542d7a574b0c
author Matt Wagantall <mattw@codeaurora.org> 1374043988 -0700
committer Matt Wagantall <mattw@codeaurora.org> 1374084239 -0700

net: flow: Prevent bringing up new CPUs during per-CPU initialization

In a rare race-condition, it's possible that a CPU will be brought
online between when the for_each_online_cpu() loop executes to
call flow_cache_cpu_prepare(), and when the hotplug notifier for
calling this same function is registered. If this happens,
flow_cache_cpu_prepare() will never be called for the new CPU,
resulting in crashes due to uninitialized per-cpu data.

Fix this by preventing CPUs from being added or removed during
this small but sensitive window.

Change-Id: Iafbbaa8a50e5c527392d130561874313720849d0
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>