Messages in this thread | | | Date | Tue, 07 Oct 2008 11:24:51 +0200 | From | Eric Dumazet <> | Subject | Re: [PATCH 3/3] Convert the UDP hash lock to RCU |
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Peter Zijlstra a écrit : > On Mon, 2008-10-06 at 23:22 +0200, Eric Dumazet wrote: > >> Or just add SLAB_DESTROY_BY_RCU to slab creation in proto_register() >> for "struct proto udp_prot/udpv6_prot" so that kmem_cache_free() >> done in sk_prot_free() can defer freeing to RCU... > > Be careful!, SLAB_DESTROY_BY_RCU just means the slab page gets > RCU-freed, this means that slab object pointers stay pointing to valid > memory, but it does _NOT_ mean those slab objects themselves remain > valid. > > The slab allocator is free to re-use those objects at any time - > irrespective of the rcu-grace period. Therefore you will have to be able > to validate that the object you point to is indeed the object you > expect, otherwise strange and wonderful things will happen. > Thanks for this clarification. I guess we really need a rcu head then :)
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