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SubjectRe: [PATCH 3/4] rwsem: implement write lock stealing
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On Sat, Feb 9, 2013 at 10:45 AM, Michel Lespinasse <walken@google.com> wrote:
> + if (waiter->type != RWSEM_WAITING_FOR_WRITE) {
> + list_del(&waiter->list);
> +
> + /* Set RWSEM_WAITING_BIAS before waking the last reader
> + * so we know there will be a remaining active locker.
> + */
> + if (!(--readers) && !list_empty(&sem->wait_list))
> + rwsem_atomic_add(RWSEM_WAITING_BIAS, sem);
> +
> + tsk = waiter->task;
> + smp_mb();

For what with mb?

> + waiter->task = NULL;
> + wake_up_process(tsk);
> + put_task_struct(tsk);
> + }
> + } while (readers);
> + sem->wait_readers = 0;


> + /* If there are no active locks, wake the front queued process(es). */

s/locks/lockers/

> + if (!(count & RWSEM_ACTIVE_MASK))
> + sem = __rwsem_do_wake(sem, RWSEM_WAKE_ANY);


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