diff mbox series

[3/5] dma-buf: return only unsignaled fences in dma_fence_unwrap_for_each v3

Message ID 20220506141009.18047-3-christian.koenig@amd.com
State New
Headers show
Series [1/5] dma-buf: cleanup dma_fence_unwrap selftest v2 | expand

Commit Message

Christian König May 6, 2022, 2:10 p.m. UTC
dma_fence_chain containers cleanup signaled fences automatically, so
filter those out from arrays as well.

v2: fix missing walk over the array
v3: massively simplify the patch and actually update the description.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 include/linux/dma-fence-unwrap.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Comments

Karolina Drobnik July 11, 2022, 9:44 a.m. UTC | #1
Hi Christian,

I'm sorry for digging this one out so late.

On 06.05.2022 16:10, Christian König wrote:
> dma_fence_chain containers cleanup signaled fences automatically, so
> filter those out from arrays as well.
> 
> v2: fix missing walk over the array
> v3: massively simplify the patch and actually update the description.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>   include/linux/dma-fence-unwrap.h | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
> index e7c219da4ed7..a4d342fef8e0 100644
> --- a/include/linux/dma-fence-unwrap.h
> +++ b/include/linux/dma-fence-unwrap.h
> @@ -43,9 +43,13 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
>    * Unwrap dma_fence_chain and dma_fence_array containers and deep dive into all
>    * potential fences in them. If @head is just a normal fence only that one is
>    * returned.
> + *
> + * Note that signalled fences are opportunistically filtered out, which
> + * means the iteration is potentially over no fence at all.
>    */
>   #define dma_fence_unwrap_for_each(fence, cursor, head)			\
>   	for (fence = dma_fence_unwrap_first(head, cursor); fence;	\
> -	     fence = dma_fence_unwrap_next(cursor))
> +	     fence = dma_fence_unwrap_next(cursor))			\
> +		if (!dma_fence_is_signaled(fence))
>   
>   #endif

It looks like this particular patch affects merging Sync Fences, which 
is reflected by failing IGT test (igt@sw_sync)[1]. The failing subtests are:
   - sync_merge - merging different fences on the same timeline, neither
		 single nor merged fences are signaled

   - sync_merge_same - merging the fence with itself on the same
		 timeline, the fence didn't signal at all

   - sync_multi_timeline_wait - merging different fences on different
		 timelines; the subtest checks if counting fences of
		 various states works. Currently, it can only see 2
		 active fences, 0 signaling (should be 2 active,
		 1 signaling)

Reverting this commit on the top of drm-tip fixes the issue, but I'm not 
sure if it wouldn't impact other places in the code. Please let me know 
if I can be of any help.

All the best,
Karolina

---------------------
[1] - reproducible locally, but can be also seen in the CI:
https://intel-gfx-ci.01.org/tree/drm-tip/index.html?testfilter=igt@sw_sync
Christian König July 11, 2022, 9:57 a.m. UTC | #2
Hi Karolina,

Am 11.07.22 um 11:44 schrieb Karolina Drobnik:
> Hi Christian,
>
> I'm sorry for digging this one out so late.
>
> On 06.05.2022 16:10, Christian König wrote:
>> dma_fence_chain containers cleanup signaled fences automatically, so
>> filter those out from arrays as well.
>>
>> v2: fix missing walk over the array
>> v3: massively simplify the patch and actually update the description.
>>
>> Signed-off-by: Christian König <christian.koenig@amd.com>
>> ---
>>   include/linux/dma-fence-unwrap.h | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/dma-fence-unwrap.h 
>> b/include/linux/dma-fence-unwrap.h
>> index e7c219da4ed7..a4d342fef8e0 100644
>> --- a/include/linux/dma-fence-unwrap.h
>> +++ b/include/linux/dma-fence-unwrap.h
>> @@ -43,9 +43,13 @@ struct dma_fence *dma_fence_unwrap_next(struct 
>> dma_fence_unwrap *cursor);
>>    * Unwrap dma_fence_chain and dma_fence_array containers and deep 
>> dive into all
>>    * potential fences in them. If @head is just a normal fence only 
>> that one is
>>    * returned.
>> + *
>> + * Note that signalled fences are opportunistically filtered out, which
>> + * means the iteration is potentially over no fence at all.
>>    */
>>   #define dma_fence_unwrap_for_each(fence, cursor, head)            \
>>       for (fence = dma_fence_unwrap_first(head, cursor); fence;    \
>> -         fence = dma_fence_unwrap_next(cursor))
>> +         fence = dma_fence_unwrap_next(cursor))            \
>> +        if (!dma_fence_is_signaled(fence))
>>     #endif
>
> It looks like this particular patch affects merging Sync Fences, which 
> is reflected by failing IGT test (igt@sw_sync)[1]. The failing 
> subtests are:
>   - sync_merge - merging different fences on the same timeline, neither
>          single nor merged fences are signaled
>
>   - sync_merge_same - merging the fence with itself on the same
>          timeline, the fence didn't signal at all
>
>   - sync_multi_timeline_wait - merging different fences on different
>          timelines; the subtest checks if counting fences of
>          various states works. Currently, it can only see 2
>          active fences, 0 signaling (should be 2 active,
>          1 signaling)
>
> Reverting this commit on the top of drm-tip fixes the issue, but I'm 
> not sure if it wouldn't impact other places in the code. Please let me 
> know if I can be of any help.


Thanks for letting me know. Not sure what's going on here, but I can 
take a look today if time permits.

Do you have a description how to easy reproduce this? E.g. how to run 
just those specific igts?

Thanks,
Christian.

>
> All the best,
> Karolina
>
> ---------------------
> [1] - reproducible locally, but can be also seen in the CI:
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fintel-gfx-ci.01.org%2Ftree%2Fdrm-tip%2Findex.html%3Ftestfilter%3Digt%40sw_sync&amp;data=05%7C01%7Cchristian.koenig%40amd.com%7C2af59c808f664f0cf04908da6321e708%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637931294507736831%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=NTI04OpP7kMsCu%2BDWsJ0%2FRIVJGJbxy36tJBImD2MQDU%3D&amp;reserved=0 
>
Karolina Drobnik July 11, 2022, 12:17 p.m. UTC | #3
Hi Christian,

On 11.07.2022 11:57, Christian König wrote:
> Hi Karolina,
> 
> Am 11.07.22 um 11:44 schrieb Karolina Drobnik:
>> Hi Christian,
>>
>> I'm sorry for digging this one out so late.
>>
>> On 06.05.2022 16:10, Christian König wrote:
>>> dma_fence_chain containers cleanup signaled fences automatically, so
>>> filter those out from arrays as well.
>>>
>>> v2: fix missing walk over the array
>>> v3: massively simplify the patch and actually update the description.
>>>
>>> Signed-off-by: Christian König <christian.koenig@amd.com>
>>> ---
>>>   include/linux/dma-fence-unwrap.h | 6 +++++-
>>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/include/linux/dma-fence-unwrap.h 
>>> b/include/linux/dma-fence-unwrap.h
>>> index e7c219da4ed7..a4d342fef8e0 100644
>>> --- a/include/linux/dma-fence-unwrap.h
>>> +++ b/include/linux/dma-fence-unwrap.h
>>> @@ -43,9 +43,13 @@ struct dma_fence *dma_fence_unwrap_next(struct 
>>> dma_fence_unwrap *cursor);
>>>    * Unwrap dma_fence_chain and dma_fence_array containers and deep 
>>> dive into all
>>>    * potential fences in them. If @head is just a normal fence only 
>>> that one is
>>>    * returned.
>>> + *
>>> + * Note that signalled fences are opportunistically filtered out, which
>>> + * means the iteration is potentially over no fence at all.
>>>    */
>>>   #define dma_fence_unwrap_for_each(fence, cursor, head)            \
>>>       for (fence = dma_fence_unwrap_first(head, cursor); fence;    \
>>> -         fence = dma_fence_unwrap_next(cursor))
>>> +         fence = dma_fence_unwrap_next(cursor))            \
>>> +        if (!dma_fence_is_signaled(fence))
>>>     #endif
>>
>> It looks like this particular patch affects merging Sync Fences, which 
>> is reflected by failing IGT test (igt@sw_sync)[1]. The failing 
>> subtests are:
>>   - sync_merge - merging different fences on the same timeline, neither
>>          single nor merged fences are signaled
>>
>>   - sync_merge_same - merging the fence with itself on the same
>>          timeline, the fence didn't signal at all
>>
>>   - sync_multi_timeline_wait - merging different fences on different
>>          timelines; the subtest checks if counting fences of
>>          various states works. Currently, it can only see 2
>>          active fences, 0 signaling (should be 2 active,
>>          1 signaling)
>>
>> Reverting this commit on the top of drm-tip fixes the issue, but I'm 
>> not sure if it wouldn't impact other places in the code. Please let me 
>> know if I can be of any help.
> 
> 
> Thanks for letting me know. Not sure what's going on here, but I can 
> take a look today if time permits.

The reproduction with IGTs should be quite easy. You'll need to 
clone/download the IGT code and follow instructions for Building[1] the 
project (make sure you have meson and ninja installed):

   https://gitlab.freedesktop.org/drm/igt-gpu-tools

Once you have it up and running, go to <igt path>/build/tests, and run 
the subtests:

   ./sw_sync --run sync_merge
   ./sw_sync --run sync_merge_same
   ./sw_sync --run sync_multi_timeline_wait

You can run all the subtests with ./sw_sync, but I think these are the 
most relevant to you.

Many thanks,
Karolina

------------------
[1] - https://gitlab.freedesktop.org/drm/igt-gpu-tools#building

> Do you have a description how to easy reproduce this? E.g. how to run 
> just those specific igts?
> 
> Thanks,
> Christian.
> 
>>
>> All the best,
>> Karolina
>>
Christian König July 11, 2022, 12:25 p.m. UTC | #4
Hi Karolina,

Am 11.07.22 um 14:17 schrieb Karolina Drobnik:
> Hi Christian,
>
> On 11.07.2022 11:57, Christian König wrote:
>> Hi Karolina,
>>
>> Am 11.07.22 um 11:44 schrieb Karolina Drobnik:
>>> Hi Christian,
>>>
>>> I'm sorry for digging this one out so late.
>>>
>>> On 06.05.2022 16:10, Christian König wrote:
>>>> dma_fence_chain containers cleanup signaled fences automatically, so
>>>> filter those out from arrays as well.
>>>>
>>>> v2: fix missing walk over the array
>>>> v3: massively simplify the patch and actually update the description.
>>>>
>>>> Signed-off-by: Christian König <christian.koenig@amd.com>
>>>> ---
>>>>   include/linux/dma-fence-unwrap.h | 6 +++++-
>>>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/include/linux/dma-fence-unwrap.h 
>>>> b/include/linux/dma-fence-unwrap.h
>>>> index e7c219da4ed7..a4d342fef8e0 100644
>>>> --- a/include/linux/dma-fence-unwrap.h
>>>> +++ b/include/linux/dma-fence-unwrap.h
>>>> @@ -43,9 +43,13 @@ struct dma_fence *dma_fence_unwrap_next(struct 
>>>> dma_fence_unwrap *cursor);
>>>>    * Unwrap dma_fence_chain and dma_fence_array containers and deep 
>>>> dive into all
>>>>    * potential fences in them. If @head is just a normal fence only 
>>>> that one is
>>>>    * returned.
>>>> + *
>>>> + * Note that signalled fences are opportunistically filtered out, 
>>>> which
>>>> + * means the iteration is potentially over no fence at all.
>>>>    */
>>>>   #define dma_fence_unwrap_for_each(fence, cursor, head)            \
>>>>       for (fence = dma_fence_unwrap_first(head, cursor); fence;    \
>>>> -         fence = dma_fence_unwrap_next(cursor))
>>>> +         fence = dma_fence_unwrap_next(cursor)) \
>>>> +        if (!dma_fence_is_signaled(fence))
>>>>     #endif
>>>
>>> It looks like this particular patch affects merging Sync Fences, 
>>> which is reflected by failing IGT test (igt@sw_sync)[1]. The failing 
>>> subtests are:
>>>   - sync_merge - merging different fences on the same timeline, neither
>>>          single nor merged fences are signaled
>>>
>>>   - sync_merge_same - merging the fence with itself on the same
>>>          timeline, the fence didn't signal at all
>>>
>>>   - sync_multi_timeline_wait - merging different fences on different
>>>          timelines; the subtest checks if counting fences of
>>>          various states works. Currently, it can only see 2
>>>          active fences, 0 signaling (should be 2 active,
>>>          1 signaling)
>>>
>>> Reverting this commit on the top of drm-tip fixes the issue, but I'm 
>>> not sure if it wouldn't impact other places in the code. Please let 
>>> me know if I can be of any help.
>>
>>
>> Thanks for letting me know. Not sure what's going on here, but I can 
>> take a look today if time permits.
>
> The reproduction with IGTs should be quite easy. You'll need to 
> clone/download the IGT code and follow instructions for Building[1] 
> the project (make sure you have meson and ninja installed):
>
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.freedesktop.org%2Fdrm%2Figt-gpu-tools&amp;data=05%7C01%7Cchristian.koenig%40amd.com%7C9a9587aefd2d4ac2d86208da63375cb6%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637931386683611766%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=4WsMutcFJ2HwBqld%2BTv9N1Tx6cbFMwJJZ6kjm5rbfoI%3D&amp;reserved=0
>
> Once you have it up and running, go to <igt path>/build/tests, and run 
> the subtests:
>
>   ./sw_sync --run sync_merge
>   ./sw_sync --run sync_merge_same
>   ./sw_sync --run sync_multi_timeline_wait
>
> You can run all the subtests with ./sw_sync, but I think these are the 
> most relevant to you.

Thanks, I've already managed to reproduce it.

Not sure what's going on here, but could be that the test case was never 
correct in the first place. Need to double check.

Thanks,
Christian.

>
> Many thanks,
> Karolina
>
> ------------------
> [1] - 
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.freedesktop.org%2Fdrm%2Figt-gpu-tools%23building&amp;data=05%7C01%7Cchristian.koenig%40amd.com%7C9a9587aefd2d4ac2d86208da63375cb6%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637931386683611766%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=FV0Ao6ra8EOyr4cOs4N7mCmpOEUUObTrgyOrd0tvEV8%3D&amp;reserved=0
>
>> Do you have a description how to easy reproduce this? E.g. how to run 
>> just those specific igts?
>>
>> Thanks,
>> Christian.
>>
>>>
>>> All the best,
>>> Karolina
>>>
Karolina Drobnik July 11, 2022, 12:41 p.m. UTC | #5
Hi Christian,

On 11.07.2022 14:25, Christian König wrote:
> Hi Karolina,
> 
> Am 11.07.22 um 14:17 schrieb Karolina Drobnik:
>> Hi Christian,
>>
>> On 11.07.2022 11:57, Christian König wrote:
>>> Hi Karolina,
>>>
>>> Am 11.07.22 um 11:44 schrieb Karolina Drobnik:
>>>> Hi Christian,
>>>>
>>>> I'm sorry for digging this one out so late.
>>>>
>>>> On 06.05.2022 16:10, Christian König wrote:
>>>>> dma_fence_chain containers cleanup signaled fences automatically, so
>>>>> filter those out from arrays as well.
>>>>>
>>>>> v2: fix missing walk over the array
>>>>> v3: massively simplify the patch and actually update the description.
>>>>>
>>>>> Signed-off-by: Christian König <christian.koenig@amd.com>
>>>>> ---
>>>>>   include/linux/dma-fence-unwrap.h | 6 +++++-
>>>>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/include/linux/dma-fence-unwrap.h 
>>>>> b/include/linux/dma-fence-unwrap.h
>>>>> index e7c219da4ed7..a4d342fef8e0 100644
>>>>> --- a/include/linux/dma-fence-unwrap.h
>>>>> +++ b/include/linux/dma-fence-unwrap.h
>>>>> @@ -43,9 +43,13 @@ struct dma_fence *dma_fence_unwrap_next(struct 
>>>>> dma_fence_unwrap *cursor);
>>>>>    * Unwrap dma_fence_chain and dma_fence_array containers and deep 
>>>>> dive into all
>>>>>    * potential fences in them. If @head is just a normal fence only 
>>>>> that one is
>>>>>    * returned.
>>>>> + *
>>>>> + * Note that signalled fences are opportunistically filtered out, 
>>>>> which
>>>>> + * means the iteration is potentially over no fence at all.
>>>>>    */
>>>>>   #define dma_fence_unwrap_for_each(fence, cursor, head)            \
>>>>>       for (fence = dma_fence_unwrap_first(head, cursor); fence;    \
>>>>> -         fence = dma_fence_unwrap_next(cursor))
>>>>> +         fence = dma_fence_unwrap_next(cursor)) \
>>>>> +        if (!dma_fence_is_signaled(fence))
>>>>>     #endif
>>>>
>>>> It looks like this particular patch affects merging Sync Fences, 
>>>> which is reflected by failing IGT test (igt@sw_sync)[1]. The failing 
>>>> subtests are:
>>>>   - sync_merge - merging different fences on the same timeline, neither
>>>>          single nor merged fences are signaled
>>>>
>>>>   - sync_merge_same - merging the fence with itself on the same
>>>>          timeline, the fence didn't signal at all
>>>>
>>>>   - sync_multi_timeline_wait - merging different fences on different
>>>>          timelines; the subtest checks if counting fences of
>>>>          various states works. Currently, it can only see 2
>>>>          active fences, 0 signaling (should be 2 active,
>>>>          1 signaling)
>>>>
>>>> Reverting this commit on the top of drm-tip fixes the issue, but I'm 
>>>> not sure if it wouldn't impact other places in the code. Please let 
>>>> me know if I can be of any help.
>>>
>>>
>>> Thanks for letting me know. Not sure what's going on here, but I can 
>>> take a look today if time permits.
>>
>> The reproduction with IGTs should be quite easy. You'll need to 
>> clone/download the IGT code and follow instructions for Building[1] 
>> the project (make sure you have meson and ninja installed):
>>
>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.freedesktop.org%2Fdrm%2Figt-gpu-tools&amp;data=05%7C01%7Cchristian.koenig%40amd.com%7C9a9587aefd2d4ac2d86208da63375cb6%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637931386683611766%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=4WsMutcFJ2HwBqld%2BTv9N1Tx6cbFMwJJZ6kjm5rbfoI%3D&amp;reserved=0 
>>
>>
>> Once you have it up and running, go to <igt path>/build/tests, and run 
>> the subtests:
>>
>>   ./sw_sync --run sync_merge
>>   ./sw_sync --run sync_merge_same
>>   ./sw_sync --run sync_multi_timeline_wait
>>
>> You can run all the subtests with ./sw_sync, but I think these are the 
>> most relevant to you.
> 
> Thanks, I've already managed to reproduce it.
> 
> Not sure what's going on here, but could be that the test case was never 
> correct in the first place. Need to double check.

That's also a possibility, but I couldn't verify it before writing to 
you, as it's not my area of expertise.

Thanks for taking a look at this.

All the best,
Karolina

> Thanks,
> Christian.
> 
>>
>> Many thanks,
>> Karolina
>>
>> ------------------
>> [1] - 
>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.freedesktop.org%2Fdrm%2Figt-gpu-tools%23building&amp;data=05%7C01%7Cchristian.koenig%40amd.com%7C9a9587aefd2d4ac2d86208da63375cb6%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637931386683611766%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=FV0Ao6ra8EOyr4cOs4N7mCmpOEUUObTrgyOrd0tvEV8%3D&amp;reserved=0 
>>
>>
>>> Do you have a description how to easy reproduce this? E.g. how to run 
>>> just those specific igts?
>>>
>>> Thanks,
>>> Christian.
>>>
>>>>
>>>> All the best,
>>>> Karolina
>>>>
>
diff mbox series

Patch

diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
index e7c219da4ed7..a4d342fef8e0 100644
--- a/include/linux/dma-fence-unwrap.h
+++ b/include/linux/dma-fence-unwrap.h
@@ -43,9 +43,13 @@  struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
  * Unwrap dma_fence_chain and dma_fence_array containers and deep dive into all
  * potential fences in them. If @head is just a normal fence only that one is
  * returned.
+ *
+ * Note that signalled fences are opportunistically filtered out, which
+ * means the iteration is potentially over no fence at all.
  */
 #define dma_fence_unwrap_for_each(fence, cursor, head)			\
 	for (fence = dma_fence_unwrap_first(head, cursor); fence;	\
-	     fence = dma_fence_unwrap_next(cursor))
+	     fence = dma_fence_unwrap_next(cursor))			\
+		if (!dma_fence_is_signaled(fence))
 
 #endif