From: Heiko Carstens <heiko.carstens@de.ibm.com>
Date: Mon, 16 Sep 2013 08:44:54 +0000 (+0200)
Subject: s390/atomic: optimize atomic_add() for constant values
X-Git-Tag: omap-for-v3.13/fixes-for-merge-window-take2~58^2~50
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5692e4d11cf5b51045a41daf295626c7fcbb698a;p=pandora-kernel.git

s390/atomic: optimize atomic_add() for constant values

If the interlocked-access facility 1 is available we can use the asi
and agsi instructions for interlocked updates if the to be added
value is a contanst and small (in the range of -128..127).
asi and agsi do not not return the old or new value, therefore these
instructions can only be used for atomic_(add|sub|inc|dec)[64].

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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