From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 19 Dec 2013 10:54:45 +0000 (+0100)
Subject: sched/deadline: Fix hotplug admission control
X-Git-Tag: v3.14-rc1~170^2~33
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=de212f18e92c952533d57c5510d2790199c75734;p=pandora-kernel.git

sched/deadline: Fix hotplug admission control

The current hotplug admission control is broken because:

  CPU_DYING -> migration_call() -> migrate_tasks() -> __migrate_task()

cannot fail and hard assumes it _will_ move all tasks off of the dying
cpu, failing this will break hotplug.

The much simpler solution is a DOWN_PREPARE handler that fails when
removing one CPU gets us below the total allocated bandwidth.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20131220171343.GL2480@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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