From: David S. Miller <davem@davemloft.net>
Date: Fri, 29 Jun 2012 08:32:45 +0000 (-0700)
Subject: ipv4: Elide fib_validate_source() completely when possible.
X-Git-Tag: v3.6-rc1~125^2~340
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7a9bc9b81a5bc6e44ebc80ef781332e4385083f2;p=pandora-kernel.git

ipv4: Elide fib_validate_source() completely when possible.

If rpfilter is off (or the SKB has an IPSEC path) and there are not
tclassid users, we don't have to do anything at all when
fib_validate_source() is invoked besides setting the itag to zero.

We monitor tclassid uses with a counter (modified only under RTNL and
marked __read_mostly) and we protect the fib_validate_source() real
work with a test against this counter and whether rpfilter is to be
done.

Having a way to know whether we need no tclassid processing or not
also opens the door for future optimized rpfilter algorithms that do
not perform full FIB lookups.

Signed-off-by: David S. Miller <davem@davemloft.net>
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