Re: [ANNOUNCE] Kernel Janitor's TODO list

Roman Zippel
2001-01-29T20:03:31Z

Hi,

On Mon, 29 Jan 2001, Andi Kleen wrote:

> You can miss wakeups. The standard pattern is:
>
> get locks
>
> add_wait_queue(&waitqueue, &wait);
> for (;;) {
> if (condition you're waiting for is true)
> break;
> unlock any non sleeping locks you need for condition
> __set_task_state(current, TASK_UNINTERRUPTIBLE);
> schedule();
> __set_task_state(current, TASK_RUNNING);
> reaquire locks
> }
> remove_wait_queue(&waitqueue, &wait);

You still miss wakeups. :)
Always set the task state first, then check the condition. See the
wait_event*() macros you mentioned for the right order.

bye, Roman