• Ying Xue's avatar
    tipc: purge tipc_net_lock lock · 7216cd94
    Ying Xue authored
    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.
    Until now above all changes have been done, so tipc_net_lock can be
    removed safely.
    Signed-off-by: Ying Xue's avatarYing Xue <ying.xue@windriver.com>
    Reviewed-by: default avatarJon Maloy <jon.maloy@ericsson.com>
    Reviewed-by: default avatarErik Hugne <erik.hugne@ericsson.com>
    Tested-by: default avatarErik Hugne <erik.hugne@ericsson.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
name_distr.c 10.2 KB