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    SubjectRe: Multitude of dst obsolescense race conditions
    On Fri, Jun 06, 2014 at 11:57:10AM -0700, Eric Dumazet wrote:
    > On Fri, 2014-06-06 at 11:12 -0700, Paul E. McKenney wrote:
    >
    > > It is probably just be me getting lost in the code, but I am not seeing
    > > a synchronize_rcu(), call_rcu(), or synchronize_net() anywhere in
    > > dst_release() or the things that it calls. If there really isn't such
    > > a call, then I don't see how the above code is safe in the case where
    > > __sk_dst_set() is invoked on one CPU just after sk_dst_get() executes
    > > the rcu_dereference() on some other CPU.
    >
    > Well, this part is fine, dst_release() do not free dst that are
    > potentially stored in sk_dst_cache
    >
    > Only the refcount is decremented.
    >
    > The bug is elsewhere, we had another thread raising this issue on netdev
    > this morning.
    >
    > I am cooking a patch to clear the mess.

    Ah, thank you, sorry for the noise!

    Thanx, Paul



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