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    SubjectRe: [PATCH 10/10 V2] workqueue: use generic attach/detach routine for rescuers
    On Mon, May 12, 2014 at 02:56:22PM +0800, Lai Jiangshan wrote:
    > There are several problems with the code that rescuers bind itself to the pool'
    > cpumask
    > 1) It uses a way different from the normal workers to bind to the cpumask
    > So we can't maintain the normal/rescuer workers under the same framework.
    > 2) The the code of cpu-binding for rescuer is complicated
    > 3) If one or more cpuhotplugs happen while the rescuer processes the
    > scheduled works, the rescuer may not be correctly bound to the cpumask of
    > the pool. This is allowed behavior, but is not good. It will be better
    > if the cpumask of the rescuer is always kept coordination with the pool
    > across any cpuhotplugs.
    >
    > Using generic attach/detach routine will solve the above problems,
    > and result much more simple code.
    >
    > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
    > static struct worker *alloc_worker(void)
    > {
    > struct worker *worker;
    > @@ -2343,8 +2279,9 @@ repeat:
    >
    > spin_unlock_irq(&wq_mayday_lock);
    >
    > - /* migrate to the target cpu if possible */
    > - worker_maybe_bind_and_lock(pool);
    > + worker_attach_to_pool(rescuer, pool);
    > +
    > + spin_lock_irq(&pool->lock);
    > rescuer->pool = pool;
    >
    > /*
    > @@ -2357,6 +2294,11 @@ repeat:
    > move_linked_works(work, scheduled, &n);
    >
    > process_scheduled_works(rescuer);
    > + spin_unlock_irq(&pool->lock);
    > +
    > + worker_detach_from_pool(rescuer, pool);
    > +
    > + spin_lock_irq(&pool->lock);

    Ah, right, this is how it's used. Yeah, it makes sense. In a long
    patchset, it usually helps to mention your intentions when structuring
    functions tho. When you're separating out detach_from_pool, just
    mention that the function will later be used to make rescuers use the
    same attach/detach framework as normal workers.

    How has this been tested?

    Thanks.

    --
    tejun


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