1. 16 4月, 2008 38 次提交
  2. 15 4月, 2008 2 次提交
    • P
      [NETNS]: The generic per-net pointers. · dec827d1
      Pavel Emelyanov 提交于
      Add the elastic array of void * pointer to the struct net.
      The access rules are simple:
      
       1. register the ops with register_pernet_gen_device to get
          the id of your private pointer
       2. call net_assign_generic() to put the private data on the
          struct net (most preferably this should be done in the
          ->init callback of the ops registered)
       3. do not store any private reference on the net_generic array;
       4. do not change this pointer while the net is alive;
       5. use the net_generic() to get the pointer.
      
      When adding a new pointer, I copy the old array, replace it
      with a new one and schedule the old for kfree after an RCU
      grace period.
      
      Since the net_generic explores the net->gen array inside rcu
      read section and once set the net->gen->ptr[x] pointer never 
      changes, this grants us a safe access to generic pointers.
      
      Quoting Paul: "... RCU is protecting -only- the net_generic 
      structure that net_generic() is traversing, and the [pointer]
      returned by net_generic() is protected by a reference counter 
      in the upper-level struct net."
      Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
      Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      dec827d1
    • P
      [NETNS]: The net-subsys IDs generator. · c93cf61f
      Pavel Emelyanov 提交于
      To make some per-net generic pointers, we need some way to address
      them, i.e. - IDs. This is simple IDA-based IDs generator for pernet
      subsystems.
      
      Addressing questions about potential checkpoint/restart problems: 
      these IDs are "lite-offsets" within the net structure and are by no 
      means supposed to be exported to the userspace.
      
      Since it will be used in the nearest future by devices only (tun,
      vlan, tunnels, bridge, etc), I make it resemble the functionality
      of register_pernet_device().
      
      The new ids is stored in the *id pointer _before_ calling the init
      callback to make this id available in this callback.
      Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c93cf61f