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    SubjectRe: [PATCH -mm 1/2] irq_work, Use llist in irq_work
    On Thu, 2011-09-01 at 16:44 +0800, Huang Ying wrote:

    > Because llist is in library, it may be used in highly contended case and
    > light/un-contended loads. So maybe code as above is best choice for llist.

    Well the thing is, if you're heavily contended you should probably be
    doing something else..

    > > Also, just noticed, why do you have different list_head/list_node
    > > structures? They're the same, a single pointer.
    > There is only one structure before (llist_head). Linus give me some
    > comments about that, suggests to use 2 structures. I think his comments
    > are reasonable. Copied here:


    > Even with this_cpu_* ops, it seems that the race condition I described
    > is still possible.
    > - use this_cpu_cmpxchg to queue irq_work into irq_work_list of CPU A
    > - preempted and resumed execution on CPU B
    > - arch_irq_work_raise on CPU B
    > Do you think so?

    No you're right, got my brain inside-out today or so..

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