> +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);
> +
I don't think there's a need to have the siglock for checking PF_EXITING,
and I also don't see why you need it for the assignment to
iocb->ki_notify.target. What is it intended to protect?
> + /*
> + * 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;
We leak the task reference here.
All in all aio_setup_sigevent is a big mess and the style is very odd.
It's also overcommented on what's beeing done instead of why.
I've attached an draft on how it should look like below.
> + /* handle setting up the sigevent for POSIX AIO signals */
> + req->ki_notify.notify = SIGEV_NONE;
> +
> + if (iocb->aio_sigeventp) {
> + ret = aio_setup_sigevent(req,
> + (struct sigevent __user *)(unsigned long)
> + iocb->aio_sigeventp);
> + if (ret)
> + goto out_put_req;
> + }
> +
> ret = aio_setup_iocb(req);
>
> if (ret)
> @@ -1610,6 +1729,10 @@ int fastcall io_submit_one(struct kioctx
> return 0;
>
> out_put_req:
> + /* Undo the sigqueue alloc if someting went bad */
> + if (req->ki_sigq)
> + sigqueue_free(req->ki_sigq);
> +
Please put this after a separate label, so only callers after
aio_setup_sigevent try to check ki_sigq.
static long aio_setup_sigevent(struct kiocb *iocb,
struct sigevent __user *user_event)
{
sigevent_t event;
struct task_struct *target;
unsigned long flags;
if (copy_from_user(&event, user_event, sizeof (event)))
return -EFAULT;
if (event.sigev_notify == SIGEV_NONE)
return 0;
iocb->ki_notify.notify = event.sigev_notify;
iocb->ki_notify.signo = event.sigev_signo;
iocb->ki_notify.value = event.sigev_value;
read_lock(&tasklist_lock);
target = good_sigevent(&event);
if (unlikely(!target || (target->flags & PF_EXITING)))
goto out_unlock;
iocb->ki_notify.target = target;
if (iocb->ki_notify.notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) {
/*
* This reference will be dropped when we're done with
* the request.
*/
get_task_struct(target);
}
read_unlock(&tasklist_lock);
/*
* 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.
*/
iocb->ki_sigq = sigqueue_alloc();
if (unlikely(!iocb->ki_sigq)) {
put_task_struct(target);
return -EAGAIN;
}
return 0;
out_unlock:
read_unlock(&tasklist_lock);
return -EINVAL;
}
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