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| 2 | |
| 3 | * generic net pointers
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| 4 |
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| 5 |
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| 6 | #ifndef __NET_GENERIC_H__
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| 7 | #define __NET_GENERIC_H__
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| 8 |
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| 9 | #include <linux/bug.h>
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| 10 | #include <linux/rcupdate.h>
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| 11 | #include <net/net_namespace.h>
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| 12 |
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| 13 | |
| 14 | * Generic net pointers are to be used by modules to put some private
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| 15 | * stuff on the struct net without explicit struct net modification
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| 16 | *
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| 17 | * The rules are simple:
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| 18 | * 1. set pernet_operations->id. After register_pernet_device you
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| 19 | * will have the id of your private pointer.
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| 20 | * 2. set pernet_operations->size to have the code allocate and free
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| 21 | * a private structure pointed to from struct net.
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| 22 | * 3. do not change this pointer while the net is alive;
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| 23 | * 4. do not try to have any private reference on the net_generic object.
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| 24 | *
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| 25 | * After accomplishing all of the above, the private pointer can be
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| 26 | * accessed with the net_generic() call.
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| 27 |
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| 28 |
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| 29 | struct net_generic {
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| 30 | union {
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| 31 | struct {
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| 32 | unsigned int len;
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| 33 | struct rcu_head rcu;
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| 34 | } s;
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| 35 |
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| 36 | DECLARE_FLEX_ARRAY(void *, ptr);
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| 37 | };
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| 38 | };
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| 39 |
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| 40 | static inline void *net_generic(const struct net *net, unsigned int id)
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| 41 | {
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| 42 | struct net_generic *ng;
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| 43 | void *ptr;
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| 44 |
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| 45 | rcu_read_lock();
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| 46 | ng = rcu_dereference(net->gen);
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| 47 | ptr = ng->ptr[id];
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| 48 | rcu_read_unlock();
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| 49 |
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| 50 | return ptr;
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| 51 | }
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| 52 | #endif
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