From: Paul E. McKenney <paul.mckenney@linaro.org>
Date: Wed, 23 Nov 2011 01:46:19 +0000 (-0800)
Subject: rcu: Avoid needlessly IPIing CPUs at GP end
X-Git-Tag: v3.3-rc1~193^2^2~19
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=84ad00cb61f1cb21f0b63bc6f7dc254399eb3830;p=pandora-kernel.git

rcu: Avoid needlessly IPIing CPUs at GP end

If a CPU enters dyntick-idle mode with callbacks pending, it will need
an IPI at the end of the grace period.  However, if it exits dyntick-idle
mode before the grace period ends, it will be needlessly IPIed at the
end of the grace period.

Therefore, this commit clears the per-CPU rcu_awake_at_gp_end flag
when a CPU determines that it does not need it.  This in turn requires
disabling interrupts across much of rcu_prepare_for_idle() in order to
avoid having nested interrupts clearing this state out from under us.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---

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