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authorPavel Emelyanov <xemul@openvz.org>2008-04-15 00:36:08 -0700
committerDavid S. Miller <davem@davemloft.net>2008-04-15 00:36:08 -0700
commitdec827d174d7f76c457238800183ca864a639365 (patch)
treeca7c04e35eda9956afef94678a2a863c3e75e2ed /net/tipc
parentc93cf61fd1d5378134f9b06703f7078067542e00 (diff)
[NETNS]: The generic per-net pointers.
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: Pavel Emelyanov <xemul@openvz.org> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc')
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