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Message-Id: <20140422.211853.1970482489817745604.davem@davemloft.net>
Date: Tue, 22 Apr 2014 21:18:53 -0400 (EDT)
From: David Miller <davem@...emloft.net>
To: ying.xue@...driver.com
Cc: jon.maloy@...csson.com, Paul.Gortmaker@...driver.com,
erik.hugne@...csson.com, netdev@...r.kernel.org,
tipc-discussion@...ts.sourceforge.net
Subject: Re: [PATCH net-next 00/11] purge tipc_net_lock
From: Ying Xue <ying.xue@...driver.com>
Date: Mon, 21 Apr 2014 10:55:41 +0800
> Now tipc routing hierarchy comprises the structures 'node', 'link'and
> 'bearer'. The whole hierarchy is protected by a big read/write lock,
> tipc_net_lock, to ensure that nothing is added or removed while code
> is accessing any of these structures. Obviously the locking policy
> makes node, link and bearer components closely bound together so that
> their relationship becomes unnecessarily complex. In the worst case,
> such locking policy not only has a negative influence on performance,
> but also it's prone to lead to deadlock occasionally.
>
> In order o decouple the complex relationship between bearer and node
> as well as link, the locking policy is adjusted as follows:
>
> - Bearer level
> RTNL lock is used on update side, and RCU is used on read side.
> Meanwhile, all bearer instances including broadcast bearer are
> saved into bearer_list array.
>
> - Node and link level
> All node instances are saved into two tipc_node_list and node_htable
> lists. The two lists are protected by node_list_lock on write side,
> and they are guarded with RCU lock on read side. All members in node
> structure including link instances are protected by node spin lock.
>
> - The relationship between bearer and node
> When link accesses bearer, it first needs to find the bearer with
> its bearer identity from the bearer_list array. When bearer accesses
> node, it can iterate the node_htable hash list with the node address
> to find the corresponding node.
>
> In the new locking policy, every component has its private locking
> solution and the relationship between bearer and node is very simple,
> that is, they can find each other with node address or bearer identity
> from node_htable hash list or bearer_list array.
Series applied, thank you.
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