netdev - [PATCH] net: Convert TCP/DCCP listening hash tables to use RCU

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Date:	Sun, 23 Nov 2008 10:33:28 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	David Miller <davem@...emloft.net>
CC:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Corey Minyard <minyard@....org>,
	Stephen Hemminger <shemminger@...tta.com>,
	benny+usenet@...rsen.dk,
	Linux Netdev List <netdev@...r.kernel.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Evgeniy Polyakov <zbr@...emap.net>,
	Christian Bell <christian@...i.com>
Subject: [PATCH] net: Convert TCP/DCCP listening hash tables to use RCU

Hi David

Please find patch to convert TCP/DCCP listening hash tables
to RCU.

A followup patch will cleanup all sk_node fields and macros
that are not used anymore.

Thanks

[PATCH] net: Convert TCP/DCCP listening hash tables to use RCU

This is the last step to be able to perform full RCU lookups
in __inet_lookup() : After established/timewait tables, we
add RCU lookups to listening hash table.

The only trick here is that a socket of a given type (TCP ipv4,
TCP ipv6, ...) can now flight between two different tables
(established and listening) during a RCU grace period, so we
must use different 'nulls' end-of-chain values for two tables.

We define a large value :

#define LISTENING_NULLS_BASE (1U << 29)

So that slots in listening table are guaranteed to have different
end-of-chain values than slots in established table. A reader can
still detect it finished its lookup in the right chain.

Signed-off-by: Eric Dumazet <dada1@...mosbay.com>
---
 include/net/inet_hashtables.h |    9 +
 net/ipv4/inet_diag.c          |    4
 net/ipv4/inet_hashtables.c    |  148 ++++++++++++++++----------------
 net/ipv4/tcp_ipv4.c           |    8 -
 net/ipv6/inet6_hashtables.c   |   94 ++++++++++++--------
 5 files changed, 147 insertions(+), 116 deletions(-)

View attachment "listening_rcu.patch" of type "text/plain" (11540 bytes)