5ee4433efe
By definition net_generic should never be called when it can return NULL. Fail conspicously with a BUG_ON to make it clear when people mess up that a NULL return should never happen. Recently there was a bug in the CAIF subsystem where it was registered with register_pernet_device instead of register_pernet_subsys. It was erroneously concluded that net_generic could validly return NULL and that net_assign_generic was buggy (when it was just inefficient). Hopefully this BUG_ON will prevent people to coming to similar erroneous conclusions in the futrue. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Tested-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
48 lines
1.1 KiB
C
48 lines
1.1 KiB
C
/*
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* generic net pointers
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*/
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#ifndef __NET_GENERIC_H__
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#define __NET_GENERIC_H__
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#include <linux/rcupdate.h>
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/*
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* Generic net pointers are to be used by modules to put some private
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* stuff on the struct net without explicit struct net modification
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*
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* The rules are simple:
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* 1. set pernet_operations->id. After register_pernet_device you
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* will have the id of your private pointer.
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* 2. set pernet_operations->size to have the code allocate and free
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* a private structure pointed to from struct net.
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* 3. do not change this pointer while the net is alive;
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* 4. do not try to have any private reference on the net_generic object.
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*
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* After accomplishing all of the above, the private pointer can be
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* accessed with the net_generic() call.
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*/
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struct net_generic {
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unsigned int len;
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struct rcu_head rcu;
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void *ptr[0];
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};
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static inline void *net_generic(const struct net *net, int id)
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{
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struct net_generic *ng;
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void *ptr;
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rcu_read_lock();
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ng = rcu_dereference(net->gen);
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BUG_ON(id == 0 || id > ng->len);
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ptr = ng->ptr[id - 1];
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rcu_read_unlock();
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BUG_ON(!ptr);
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return ptr;
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}
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#endif
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