From: Lai Jiangshan <laijs@cn.fujitsu.com>
Date: Thu, 29 Nov 2012 08:46:05 +0000 (+0800)
Subject: srcu: Remove checks preventing offline CPUs from calling srcu_read_lock()
X-Git-Tag: v3.9-rc1~175^2^2~4
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3bc97a782cc8c112f64a25143452b06206364cc8;p=pandora-kernel.git

srcu: Remove checks preventing offline CPUs from calling srcu_read_lock()

SRCU has its own statemachine and no longer relies on normal RCU.
Its read-side critical section can now be used by an offline CPU, so this
commit removes the check and the comments, reverting the SRCU portion
of c0d6d01b (rcu: Check for illegal use of RCU from offlined CPUs).

It also makes the code match the comments in whatisRCU.txt:

g.	Do you need read-side critical sections that are respected
	even though they are in the middle of the idle loop, during
	user-mode execution, or on an offlined CPU?  If so, SRCU is the
	only choice that will work for you.

[ paulmck: There is at least one remaining issue, namely use of lockdep
	   with tracing enabled. ]

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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