Messages in this thread | | | Subject | Re: [PATCH 1/2] rcu: add rcu_access_pointer and rcu_dereference_protect | From | Eric Dumazet <> | Date | Wed, 07 Apr 2010 18:29:17 +0200 |
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Le mercredi 07 avril 2010 à 17:19 +0100, David Howells a écrit :
> Why not: > > ASSERT(atomic_read(&sk->sk_wmem_alloc) == 0); > filter = rcu_dereference(sk->sk_filter); > > This is much clearer, and you're not combining an unrelated assertion with the > RCU dereference.
1) Because we want the check being done only when CONFIG_PROVE_RCU is set.
2) Because rcu_dereference() default condition is : 'Am I owning rcu_read_lock() or equivalent'. In this context, I am _not_ owning rcu lock, so we will trigger a warning.
So this is best done as is :)
I personally find this very clear and clean, this is why I acked Paul patch :)
If we were 100% sure testing sk_wmem_alloc is not necessary, we would have put :
filter = rcu_dereference_check(sk->sk_filter, 1);
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