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    SubjectRe: [PATCH 1/2] rcu: add rcu_access_pointer and rcu_dereference_protect
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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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