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authorDavid S. Miller <davem@davemloft.net>2014-03-27 13:08:45 -0400
committerDavid S. Miller <davem@davemloft.net>2014-03-27 13:08:45 -0400
commitb5b6bc32a380cf3d40dd0019e900815a06f6dc3b (patch)
tree829cd112db96c7c1e7fcacb9544f36703c06ac4a /Documentation/ptp
parent1dbe136938df6633042b5674abdd2e08542168f3 (diff)
parentdde2026608fbf24e1687a2b62c4752022f429252 (diff)
Merge branch 'tipc-next'
Ying Xue says: ==================== tipc: clean up bearer and node layer This is another commit series which aims at facilitating future changes to the locking policy around nodes, links and bearers. Currently, the 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 any of these structures is being accessed. Obviously the locking policy makes node, link and bearer components closely bound together so that their relationship becomes extremely 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 to 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. But, prior to these changes, we need to do some necessary cleanup and code consolidation. This is what we do with this commit series. In a later series we will replace net_lock with RTNL as well as RCU lock to deploy the new locking policy. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
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