Am 13.12.18 um 12:37 schrieb Chris Wilson:
> Quoting Chunming Zhou (2018-12-11 10:34:45)
>> From: Christian König <ckoenig.leichtzumerken@xxxxxxxxx>
>>
>> Implement finding the right timeline point in drm_syncobj_find_fence.
>>
>> v2: return -EINVAL when the point is not submitted yet.
>> v3: fix reference counting bug, add flags handling as well
>>
>> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
>> ---
>> drivers/gpu/drm/drm_syncobj.c | 43 ++++++++++++++++++++++++++++++++---
>> 1 file changed, 40 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
>> index 76ce13dafc4d..d964b348ecba 100644
>> --- a/drivers/gpu/drm/drm_syncobj.c
>> +++ b/drivers/gpu/drm/drm_syncobj.c
>> @@ -231,16 +231,53 @@ int drm_syncobj_find_fence(struct drm_file *file_private,
>> struct dma_fence **fence)
>> {
>> struct drm_syncobj *syncobj = drm_syncobj_find(file_private, handle);
>> - int ret = 0;
>> + struct syncobj_wait_entry wait;
>> + int ret;
>>
>> if (!syncobj)
>> return -ENOENT;
>>
>> *fence = drm_syncobj_fence_get(syncobj);
>> - if (!*fence) {
>> + drm_syncobj_put(syncobj);
>> +
>> + if (*fence) {
>> + ret = dma_fence_chain_find_seqno(fence, point);
>> + if (!ret)
>> + return 0;
>> + dma_fence_put(*fence);
>> + } else {
>> ret = -EINVAL;
>> }
>> - drm_syncobj_put(syncobj);
>> +
>> + if (!(flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT))
>> + return ret;
>> +
>> + memset(&wait, 0, sizeof(wait));
>> + wait.task = current;
>> + wait.point = point;
>> + drm_syncobj_fence_add_wait(syncobj, &wait);
>> +
>> + do {
>> + set_current_state(TASK_INTERRUPTIBLE);
>> + if (wait.fence) {
>> + ret = 0;
>> + break;
>> + }
>> +
>> + if (signal_pending(current)) {
>> + ret = -ERESTARTSYS;
>> + break;
>> + }
>> +
>> + schedule();
>> + } while (1);
> I've previously used a dma_fence_proxy so that we could do nonblocking
> waits on future submits. That would be preferrable (a requirement for
> our stupid BKL-driven code).
That is exactly what I would definitely NAK.
I would rather say we should come up with a wait_multiple_events() macro
and completely nuke the custom implementation of this in:
1. dma_fence_default_wait and dma_fence_wait_any_timeout
2. the radeon fence implementation
3. the nouveau fence implementation
4. the syncobj code
Cause all of them do exactly the same. The dma_fence implementation
unfortunately came up with a custom event handling mechanism instead of
extending the core Linux wait_event() system.
This in turn lead to a lot of this duplicated handling.
Christian.
> -Chris
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