rcu_offline_cpu and rcu_move_batch have been broken since the list_head's
in struct rcu_head and struct rcu_data were replaced with singly-linked
lists:

  CC      kernel/rcupdate.o
kernel/rcupdate.c: In function `rcu_move_batch':
kernel/rcupdate.c:222: warning: passing arg 2 of `list_add_tail' from
incompatible pointer type
kernel/rcupdate.c: In function `rcu_offline_cpu':
kernel/rcupdate.c:239: warning: passing arg 1 of `rcu_move_batch' from
incompatible pointer type
kernel/rcupdate.c:240: warning: passing arg 1 of `rcu_move_batch' from
incompatible pointer type
kernel/rcupdate.c:236: warning: label `unlock' defined but not used

Kernel crashes when you try to offline a cpu, not surprisingly.

It also looks like rcu_move_batch isn't preempt-safe so I touched that up,
and got rid of an unused label in rcu_offline_cpu.
Signed-off-by: Nathan Lynch <nathanl@austin.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>