On Mon, Oct 26, 2020 at 09:05:52AM +0800, Li, Aubrey wrote:
[..]
> > +int sched_core_share_tasks(struct task_struct *t1, struct task_struct *t2)
> > +{
> > + struct sched_core_task_write_tag wr = {}; /* for stop machine. */
> > + bool sched_core_put_after_stopper = false;
> > + unsigned long cookie;
> > + int ret = -ENOMEM;
> > +
> > + mutex_lock(&sched_core_tasks_mutex);
> > +
> > + /*
> > + * NOTE: sched_core_get() is done by sched_core_alloc_task_cookie() or
> > + * sched_core_put_task_cookie(). However, sched_core_put() is done
> > + * by this function *after* the stopper removes the tasks from the
> > + * core queue, and not before. This is just to play it safe.
> > + */
> > + if (t2 == NULL) {
> > + if (t1->core_task_cookie) {
> > + sched_core_put_task_cookie(t1->core_task_cookie);
> > + sched_core_put_after_stopper = true;
> > + wr.tasks[0] = t1; /* Keep wr.cookies[0] reset for t1. */
> > + }
> > + } else if (t1 == t2) {
> > + /* Assign a unique per-task cookie solely for t1. */
> > +
> > + cookie = sched_core_alloc_task_cookie();
> > + if (!cookie)
> > + goto out_unlock;
> > +
> > + if (t1->core_task_cookie) {
> > + sched_core_put_task_cookie(t1->core_task_cookie);
> > + sched_core_put_after_stopper = true;
> > + }
> > + wr.tasks[0] = t1;
> > + wr.cookies[0] = cookie;
> > + } else
> > + /*
> > + * t1 joining t2
> > + * CASE 1:
> > + * before 0 0
> > + * after new cookie new cookie
> > + *
> > + * CASE 2:
> > + * before X (non-zero) 0
> > + * after 0 0
> > + *
> > + * CASE 3:
> > + * before 0 X (non-zero)
> > + * after X X
> > + *
> > + * CASE 4:
> > + * before Y (non-zero) X (non-zero)
> > + * after X X
> > + */
> > + if (!t1->core_task_cookie && !t2->core_task_cookie) {
> > + /* CASE 1. */
> > + cookie = sched_core_alloc_task_cookie();
> > + if (!cookie)
> > + goto out_unlock;
> > +
> > + /* Add another reference for the other task. */
> > + if (!sched_core_get_task_cookie(cookie)) {
> > + return -EINVAL;
>
> ret = -EINVAL; mutex is not released otherwise...
Good find and will fix.
Minor suggestion: Could you truncate your emails when replying?
thanks,
- Joel
