On 22/05/18 18:22, Ezequiel Garcia wrote:
>>> @@ -1615,7 +1762,12 @@ static void __vb2_dqbuf(struct vb2_buffer *vb)
>>> return;
>>>
>>> vb->state = VB2_BUF_STATE_DEQUEUED;
>>> -
>>> + if (vb->in_fence) {
>>> + if (dma_fence_remove_callback(vb->in_fence, &vb->fence_cb))
>>> + __vb2_buffer_put(vb);
>>> + dma_fence_put(vb->in_fence);
>>> + vb->in_fence = NULL;
>>> + }
>>> /* unmap DMABUF buffer */
>>> if (q->memory == VB2_MEMORY_DMABUF)
>>> for (i = 0; i < vb->num_planes; ++i) {
>>> @@ -1653,7 +1805,7 @@ int vb2_core_dqbuf(struct vb2_queue *q, unsigned int *pindex, void *pb,
>>> if (pindex)
>>> *pindex = vb->index;
>>>
>>> - /* Fill buffer information for the userspace */
>>> + /* Fill buffer information for userspace */
>>> if (pb)
>>> call_void_bufop(q, fill_user_buffer, vb, pb);
>>>
>>> @@ -1700,8 +1852,8 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
>>> if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
>>> for (i = 0; i < q->num_buffers; ++i)
>>> if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE) {
>>> - pr_warn("driver bug: stop_streaming operation is leaving buf %p in active state\n",
>>> - q->bufs[i]);
>>> + pr_warn("driver bug: stop_streaming operation is leaving buf[%d] 0x%p in active
>>> state\n",
>>> + q->bufs[i]->index, q->bufs[i]);
>>> vb2_buffer_done(q->bufs[i], VB2_BUF_STATE_ERROR);
>>> }
>>
>> Shouldn't any pending fences be canceled here?
>>
>
> No, we don't have to flush -- that's the reason of the refcount :)
> The qbuf_work won't do anything if all the buffers are returned
> by the driver (with error or done state), and if !streaming.
>
> Also, note that's why qbuf_work checks for the queued state, and not
> for the error state.
>
>> I feel uncomfortable with the refcounting of buffers, I'd rather that when we
>> cancel the queue all fences for buffers are removed/canceled/whatever.
>>
>> Is there any reason for refcounting if we cancel all pending fences here?
>>
>> Note that besides canceling fences you also need to cancel/flush __qbuf_work.
>>
>>
>
> Like I said above, I'm trying to avoid cancel/flushing the workqueue.
> Currently, I believe it works fine without any flushing, provided we refcount
> the buffers.
>
> The problem with cancelling the workqueue, is that you need to unlock the queue
> lock, to avoid a deadlock. It seemed to me that having a refcount is more natural.
>
> Thoughts?
>
I'll take another look tomorrow morning. Do you have a public git tree containing
this series that I can browse?
Regards,
Hans
