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SubjectRe: [PATCH -mm 3/3][AIO] - AIO completion signal notification
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On Thu, 2006-11-09 at 16:59 +0100, Sébastien Dugué wrote:

> +
> +static long aio_setup_sigevent(struct kiocb *iocb,
> + struct sigevent __user *user_event)
> +{
> + int error = 0;
> + sigevent_t event;
> + struct task_struct *target;
> + unsigned long flags;
> +
> + if (!access_ok(VERIFY_READ, user_event, sizeof(struct sigevent)))
> + return -EFAULT;
> +
> + if (copy_from_user(&event, user_event, sizeof (event)))
> + return -EFAULT;
> +
> + /* Check for the SIGEV_NONE case */
> + if (event.sigev_notify == SIGEV_NONE)
> + return 0;
> +
> + /* Setup the request completion notification parameters */
> + iocb->ki_notify.notify = event.sigev_notify;
> + iocb->ki_notify.signo = event.sigev_signo;
> + iocb->ki_notify.value = event.sigev_value;
> +
> + /* Now get the notification target */
> + read_lock(&tasklist_lock);
> +
> + if ((target = good_sigevent(&event))) {
> +
> + spin_lock_irqsave(&target->sighand->siglock, flags);
> +
> + if (!(target->flags & PF_EXITING)) {
> + iocb->ki_notify.target = target;
> +
> + spin_unlock_irqrestore(&target->sighand->siglock, flags);
> +
> + /*
> + * Get a ref on the task. It is dropped in really_put_req()
> + * when we're done with the iocb, be it from the normal
> + * completion path, the cancellation path or an error path.
> + */
> + if (iocb->ki_notify.notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
> + get_task_struct(target);
> + } else {
> + spin_unlock_irqrestore(&target->sighand->siglock, flags);
> + error = -EINVAL;
> + }
> + } else
> + error = -EINVAL;
> +
> + read_unlock(&tasklist_lock);
> +
> + if (!error) {
> + /*
> + * Alloc a sigqueue for this request
> + *
> + * NOTE: we cannot free the sigqueue in the completion path as
> + * the signal may not have been delivered to the target task.
> + * Therefore it has to be freed in __sigqueue_free() when the
> + * signal is collected if si_code is SI_ASYNCIO.
> + */
> + if (unlikely(!(iocb->ki_sigq = sigqueue_alloc())))
> + error = -EAGAIN;

Don't you have to do put_task_struct() here ?

> + }
> +
> +
> + return error;
> +}
> +

Thanks,
Badari

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