sched, dl: Convert switched_{from, to}_dl() / prio_changed_dl() to balance callbacks

sched, dl: Convert switched_{from, to}_dl() / prio_changed_dl() to balance callbacks

commit 9916e214998a4a363b152b637245e5c958067350 upstream.

Remove the direct {push,pull} balancing operations from
switched_{from,to}_dl() / prio_changed_dl() and use the balance
callback queue.

Again, err on the side of too many reschedules; since too few is a
hard bug while too many is just annoying.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: ktkhai@parallels.com
Cc: rostedt@goodmis.org
Cc: juri.lelli@gmail.com
Cc: pang.xunlei@linaro.org
Cc: oleg@redhat.com
Cc: wanpeng.li@linux.intel.com
Cc: umgwanakikbuti@gmail.com
Link: http://lkml.kernel.org/r/20150611124742.968262663@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[Conflicts: kernel/sched/deadline.c]
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
[bwh: Backported to 3.16:
 - The check_resched / !CONFIG_SMP case in switched_to_dl() is different
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>