linux-kernel - Re: [PATCH 3/3] dma-buf: Check status of enable-signaling bit on debug

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Date:   Fri, 30 Sep 2022 00:00:22 +0530
From:   "Yadav, Arvind" <arvyadav@....com>
To:     Christian König <christian.koenig@....com>,
        Arvind Yadav <Arvind.Yadav@....com>, andrey.grodzovsky@....com,
        shashank.sharma@....com, amaranath.somalapuram@....com,
        Arunpravin.PaneerSelvam@....com, sumit.semwal@...aro.org,
        gustavo@...ovan.org, airlied@...ux.ie, daniel@...ll.ch,
        linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linaro-mm-sig@...ts.linaro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] dma-buf: Check status of enable-signaling bit on
 debug


On 9/29/2022 11:48 PM, Christian König wrote:
> Am 27.09.22 um 19:24 schrieb Arvind Yadav:
>> Fence signaling must be enabled to make sure that
>> the dma_fence_is_signaled_locked() function ever returns true.
>> Since drivers and implementations sometimes mess this up,
>> this ensures correct behaviour when DMABUF_DEBUG_ENABLE_SIGNALING
>> is used during debugging.
>> This should make any implementation bugs resulting in not
>> signaled fences much more obvious.
>
> Are all IGT tests now passing with this? That would be a bit 
> unfortunate because it means we still have missed the bug in drm_syncobj.
>
IGT has these test cases related to syncobj (syncobj_basic, 
syncobj_timeline and syncobj_wait)and all are passing.

I will check syncobj and let you know.

~Arvind

> Christian.
>
>>
>> Signed-off-by: Arvind Yadav <Arvind.Yadav@....com>
>> ---
>>   include/linux/dma-fence.h | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
>> index 775cdc0b4f24..5156dc6be0a6 100644
>> --- a/include/linux/dma-fence.h
>> +++ b/include/linux/dma-fence.h
>> @@ -398,6 +398,11 @@ void dma_fence_enable_sw_signaling(struct 
>> dma_fence *fence);
>>   static inline bool
>>   dma_fence_is_signaled_locked(struct dma_fence *fence)
>>   {
>> +#ifdef CONFIG_DMABUF_DEBUG_ENABLE_SIGNALING
>> +    if (!test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags))
>> +        return false;
>> +#endif
>> +
>>       if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
>>           return true;
>