On Mon, Aug 29, 2016 at 04:43:04PM +0300, Joonas Lahtinen wrote:
> On su, 2016-08-28 at 21:46 +0100, Chris Wilson wrote:
> > +static void __i915_sw_fence_wake_up_all(struct i915_sw_fence *fence,
> > + struct list_head *continuation)
> > +{
> > + wait_queue_head_t *x = &fence->wait;
>
> Rather mystique variable naming to me.
>From trying to keep familarity with struct completion.
> > + * (and so added to the list to be woken).
> > + */
> > +
> > + smp_mb__before_spinlock();
> > + spin_lock_irqsave_nested(&x->lock, flags, 1 + !!continuation);
> > + if (continuation) {
> > + list_splice_tail_init(&x->task_list, continuation);
> > + } else {
> > + LIST_HEAD(extra);
> > +
> > + do {
> > + __wake_up_locked_key(x, TASK_NORMAL, &extra);
>
> It might be worth mentioning here that we've rigged our callback so
> that it will be called synchronously here so that the code can be
> understood with less waitqueue internal digging.
We're not the only set of callback on this list, we also allow for
regular wait_event entries.
> > + if (list_empty(&extra))
> > + break;
> > +
> > + list_splice_tail_init(&extra, &x->task_list);
> > + } while (1);
>
> Why exactly do you loop here, shouldn't single invocation of
> __wake_up_locked_key trigger all the callbacks and result in all the
> entries being listed?
We handle recursion of fence completion by extending the task_list in
the top-level fence, and handle the extra fence to be woken (which will
remove them from the task list again) by looping.
> > +void i915_sw_fence_init(struct i915_sw_fence *fence, i915_sw_fence_notify_t fn)
> > +{
> > + BUG_ON((unsigned long)fn & ~I915_SW_FENCE_MASK);
> > +
> > + init_waitqueue_head(&fence->wait);
> > + kref_init(&fence->kref);
> > + atomic_set(&fence->pending, 1);
>
> fence->pending = ATOMIC_INIT(1);
Tried. ATOMIC_INIT is only valid in declarations.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
