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

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Message-ID: <a4790844-825f-839d-ed9a-104d4b589290@amd.com>
Date:   Fri, 30 Sep 2022 13:02:44 +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 9/30/2022 12:02 AM, Christian König wrote:
> Am 29.09.22 um 20:30 schrieb Yadav, Arvind:
>>
>> 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.
>
> Maybe CC the Intel list and let their CI systems take a look. That's 
> usually rather valuable.

There is one IGT subtest is failing which is related to syncobj. I will 
fix this and submit the patch.

  igt_subtest("host-signal-points")
                 test_host_signal_points(fd);

>
> Thanks,
> Christian.
>
>>
>> ~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;
>>>
>