At Tue, 18 Sep 2007 13:54:23 +0200,
Rene Herman wrote:
>
> Hi.
>
> While looking through ALSA for schedule_timeout() calls, I ran into:
>
> int snd_mixart_send_msg(...)
> {
>
> [ ... ]
>
> set_current_state(TASK_UNINTERRUPTIBLE);
> add_wait_queue(&mgr->msg_sleep, &wait);
> spin_unlock_irq(&mgr->msg_lock);
> timeout = schedule_timeout(MSG_TIMEOUT_JIFFIES);
> remove_wait_queue(&mgr->msg_sleep, &wait);
>
> if (! timeout) {
> /* error - no ack */
> mutex_unlock(&mgr->msg_mutex);
> snd_printk(KERN_ERR "error: no reponse on msg %x\n",
> msg_frame);
> return -EIO;
> }
>
> [ ... ]
>
> }
>
> and the same in snd_mixart_send_msg_wait_notif().
>
> I believe there to be something wrong with this code. A schedule_timeout()
> in TASK_UNINTERRUPTIBLE is always going to return 0.
No, it returns the time left at the point it's woken up.
*_uninterruptible() ignores signals but not wake_up() itself
(otherwise it makes no sense). The description in the kernel comment
is misleading indeed.
Takashi
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