sched/deadline: Remove cpu_active_mask from cpudl_find()
sched/deadline: Remove cpu_active_mask from cpudl_find()

cpu_active_mask is rarely changed (only on hotplug), so remove this
operation to gain a little performance.

If there is a change in cpu_active_mask, rq_online_dl() and
rq_offline_dl() should take care of it normally, so cpudl::free_cpus
carries enough information for us.

For the rare case when a task is put onto a dying cpu (which
rq_offline_dl() can't handle in a timely fashion), it will be
handled through _cpu_down()->...->multi_cpu_stop()->migration_call()
->migrate_tasks(), preventing the task from hanging on the
dead cpu.

Cc: Juri Lelli <bdc6bcd4e8b34b4b92413d758024aeca6da0e459@gmail.com>
Signed-off-by: Xunlei Pang <8f3df7547938bf466547d5e4573831d5224028fc@linaro.org>
[peterz: changelog]
Signed-off-by: Peter Zijlstra (Intel) <3fddac958924aef220f202ca567388ddab3f14a8@infradead.org>
Link: http://lkml.kernel.org/r/1421642980-10045-2-git-send-email-8f3df7547938bf466547d5e4573831d5224028fc@linaro.org
Cc: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>
Cc: 2578944098299abf708b08eff6fcf60565553586@vger.kernel.org
Signed-off-by: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@kernel.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs