The following series converts block/mq to the new hotplug state
machine. The series is against block.git/for-next and depends on
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git smp/for-block
This branch contains the necessary infrastructure for multi-instance
callbacks which allows us to remove blk-mq-cpu.c completely. It can be
pulled into the block tree.