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From: "Christian König" <christian.koenig@amd.com>
To: "Rob Clark" <robdclark@gmail.com>,
	dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
	"Christian König" <ckoenig.leichtzumerken@gmail.com>,
	"Michel Dänzer" <michel@daenzer.net>,
	"Pekka Paalanen" <ppaalanen@gmail.com>,
	"Rob Clark" <robdclark@chromium.org>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	"Gustavo Padovan" <gustavo@padovan.org>,
	"open list:SYNC FILE FRAMEWORK" <linux-media@vger.kernel.org>,
	"open list" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 6/9] dma-buf/fence-array: Add fence deadline support
Date: Thu, 9 Sep 2021 08:55:38 +0200	[thread overview]
Message-ID: <dae7e0ce-5159-b935-2387-b6a6a961be5a@amd.com> (raw)
In-Reply-To: <YTj6S1yVvBPAZ9RJ@phenom.ffwll.local>

Am 08.09.21 um 20:00 schrieb Daniel Vetter:
> On Fri, Sep 03, 2021 at 11:47:57AM -0700, Rob Clark wrote:
>> From: Rob Clark <robdclark@chromium.org>
>>
>> Signed-off-by: Rob Clark <robdclark@chromium.org>
>> ---
>>   drivers/dma-buf/dma-fence-array.c | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c
>> index d3fbd950be94..8d194b09ee3d 100644
>> --- a/drivers/dma-buf/dma-fence-array.c
>> +++ b/drivers/dma-buf/dma-fence-array.c
>> @@ -119,12 +119,23 @@ static void dma_fence_array_release(struct dma_fence *fence)
>>   	dma_fence_free(fence);
>>   }
>>   
>> +static void dma_fence_array_set_deadline(struct dma_fence *fence,
>> +					 ktime_t deadline)
>> +{
>> +	struct dma_fence_array *array = to_dma_fence_array(fence);
>> +	unsigned i;
>> +
>> +	for (i = 0; i < array->num_fences; ++i)
>> +		dma_fence_set_deadline(array->fences[i], deadline);
> Hm I wonder whether this can go wrong, and whether we need Christian's
> massive fence iterator that I've seen flying around. If you nest these
> things too much it could all go wrong I think. I looked at other users
> which inspect dma_fence_array and none of them have a risk for unbounded
> recursion.

That should work fine or at least doesn't add anything new which could 
go boom.

The dma_fence_array() can't contain other dma_fence_array or 
dma_fence_chain objects or it could end up in a recursion and corrupt 
the kernel stack.

That's a well known limitation for other code paths as well.

So Reviewed-by: Christian König <christian.koenig@amd.com> for this one.

Regards,
Christian.

>
> Maybe check with Christian.
> -Daniel
>
>
>> +}
>> +
>>   const struct dma_fence_ops dma_fence_array_ops = {
>>   	.get_driver_name = dma_fence_array_get_driver_name,
>>   	.get_timeline_name = dma_fence_array_get_timeline_name,
>>   	.enable_signaling = dma_fence_array_enable_signaling,
>>   	.signaled = dma_fence_array_signaled,
>>   	.release = dma_fence_array_release,
>> +	.set_deadline = dma_fence_array_set_deadline,
>>   };
>>   EXPORT_SYMBOL(dma_fence_array_ops);
>>   
>> -- 
>> 2.31.1
>>


  reply	other threads:[~2021-09-09  6:55 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-03 18:47 [PATCH v3 0/9] dma-fence: Deadline awareness Rob Clark
2021-09-03 18:47 ` [PATCH v3 1/9] dma-fence: Add deadline awareness Rob Clark
2021-09-08 17:55   ` Daniel Vetter
2021-09-03 18:47 ` [PATCH v3 2/9] drm/vblank: Add helper to get next vblank time Rob Clark
2021-09-03 18:47 ` [PATCH v3 3/9] drm/atomic-helper: Set fence deadline for vblank Rob Clark
2021-09-03 18:47 ` [PATCH v3 4/9] drm/scheduler: Add fence deadline support Rob Clark
2021-09-08 17:45   ` Daniel Vetter
2021-09-09  6:22     ` Christian König
2021-09-14 13:38       ` Daniel Vetter
2021-09-21 15:57     ` Rob Clark
2021-09-21 16:35       ` Rob Clark
2021-09-21 16:45         ` Christian König
2021-09-21 20:09   ` Andrey Grodzovsky
2021-09-21 20:47     ` Rob Clark
2021-09-22  2:18       ` Andrey Grodzovsky
2021-09-22  3:32         ` Rob Clark
2021-09-22 14:31           ` Andrey Grodzovsky
2021-09-22 15:01             ` Rob Clark
2021-09-03 18:47 ` [PATCH v3 5/9] drm/msm: Add deadline based boost support Rob Clark
2021-09-08 17:48   ` Daniel Vetter
2021-09-08 17:57     ` Rob Clark
2021-09-03 18:47 ` [PATCH v3 6/9] dma-buf/fence-array: Add fence deadline support Rob Clark
2021-09-08 18:00   ` Daniel Vetter
2021-09-09  6:55     ` Christian König [this message]
2021-09-03 18:47 ` [PATCH v3 7/9] dma-buf/fence-chain: " Rob Clark
2021-09-08 17:54   ` Daniel Vetter
2021-09-08 18:19     ` Rob Clark
2021-09-08 18:45       ` Daniel Vetter
2021-09-09  6:31         ` Christian König
2021-09-03 18:47 ` [PATCH v3 8/9] dma-buf/sync_file: Add SET_DEADLINE ioctl Rob Clark
2021-09-08 17:50   ` Daniel Vetter
2021-09-08 18:23     ` Rob Clark
2021-09-08 18:49       ` Daniel Vetter
2021-09-08 19:40         ` Rob Clark
2021-09-08 21:10           ` Daniel Vetter
2021-09-21 18:08             ` Rob Clark
2021-09-27  8:42   ` Pekka Paalanen
2021-09-27  8:53     ` Christian König
2021-09-27 14:36     ` Rob Clark
2021-09-28  7:57       ` Pekka Paalanen
2021-09-03 18:48 ` [PATCH v3 9/9] dma-buf/sw_sync: Add fence deadline support Rob Clark
2021-09-09 16:16 ` [PATCH v3 0/9] dma-fence: Deadline awareness Simon Ser
2021-09-09 16:35   ` Rob Clark
2021-09-09 16:42     ` Simon Ser
2021-09-09 17:08       ` Rob Clark

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