This lock is only used in the TX path and thus in process context. Therefore
we can use a much lighter spinlock variant.
Signed-off-by: NGertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: NIvo van Doorn <IvDoorn@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>