[v2] dma-buf: To check enable signaling before signaled

[PATCH v2 2/4] dma-buf: enable signaling for the stub fence on debug

Posted by Arvind Yadav 3 years, 7 months ago

Here's on debug enabling software signaling for the stub fence
which is always signaled. This fence should enable software
signaling otherwise the AMD GPU scheduler will cause a GPU reset
due to a GPU scheduler cleanup activity timeout.

Signed-off-by: Arvind Yadav <Arvind.Yadav@amd.com>
---

Changes in v1 :
1- Addressing Christian's comment to remove unnecessary callback.
2- Replacing CONFIG_DEBUG_WW_MUTEX_SLOWPATH instead of CONFIG_DEBUG_FS.
3- The version of this patch is also changed and previously
it was [PATCH 3/4]

---
 drivers/dma-buf/dma-fence.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 066400ed8841..2378b12538c4 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -27,6 +27,10 @@ EXPORT_TRACEPOINT_SYMBOL(dma_fence_signaled);
 static DEFINE_SPINLOCK(dma_fence_stub_lock);
 static struct dma_fence dma_fence_stub;
 
+#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
+static bool __dma_fence_enable_signaling(struct dma_fence *fence);
+#endif
+
 /*
  * fence context counter: each execution context should have its own
  * fence context, this allows checking if fences belong to the same
@@ -136,6 +140,9 @@ struct dma_fence *dma_fence_get_stub(void)
 			       &dma_fence_stub_ops,
 			       &dma_fence_stub_lock,
 			       0, 0);
+#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
+		__dma_fence_enable_signaling(&dma_fence_stub);
+#endif
 		dma_fence_signal_locked(&dma_fence_stub);
 	}
 	spin_unlock(&dma_fence_stub_lock);
-- 
2.25.1

Re: [PATCH v2 2/4] dma-buf: enable signaling for the stub fence on debug

Posted by Christian König 3 years, 7 months ago


Am 05.09.22 um 18:35 schrieb Arvind Yadav:
> Here's on debug enabling software signaling for the stub fence
> which is always signaled. This fence should enable software
> signaling otherwise the AMD GPU scheduler will cause a GPU reset
> due to a GPU scheduler cleanup activity timeout.
>
> Signed-off-by: Arvind Yadav <Arvind.Yadav@amd.com>
> ---
>
> Changes in v1 :
> 1- Addressing Christian's comment to remove unnecessary callback.
> 2- Replacing CONFIG_DEBUG_WW_MUTEX_SLOWPATH instead of CONFIG_DEBUG_FS.
> 3- The version of this patch is also changed and previously
> it was [PATCH 3/4]
>
> ---
>   drivers/dma-buf/dma-fence.c | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
> index 066400ed8841..2378b12538c4 100644
> --- a/drivers/dma-buf/dma-fence.c
> +++ b/drivers/dma-buf/dma-fence.c
> @@ -27,6 +27,10 @@ EXPORT_TRACEPOINT_SYMBOL(dma_fence_signaled);
>   static DEFINE_SPINLOCK(dma_fence_stub_lock);
>   static struct dma_fence dma_fence_stub;
>   
> +#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
> +static bool __dma_fence_enable_signaling(struct dma_fence *fence);
> +#endif
> +

I would rename the function to something like 
dma_fence_enable_signaling_locked().

And please don't add any #ifdef if it isn't absolutely necessary. This 
makes the code pretty fragile.

>   /*
>    * fence context counter: each execution context should have its own
>    * fence context, this allows checking if fences belong to the same
> @@ -136,6 +140,9 @@ struct dma_fence *dma_fence_get_stub(void)
>   			       &dma_fence_stub_ops,
>   			       &dma_fence_stub_lock,
>   			       0, 0);
> +#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
> +		__dma_fence_enable_signaling(&dma_fence_stub);
> +#endif

Alternatively in this particular case you could just set the bit 
manually here since this is part of the dma_fence code anyway.

Christian.

>   		dma_fence_signal_locked(&dma_fence_stub);
>   	}
>   	spin_unlock(&dma_fence_stub_lock);

Re: [PATCH v2 2/4] dma-buf: enable signaling for the stub fence on debug

Posted by Yadav, Arvind 3 years, 6 months ago

On 9/6/2022 12:39 PM, Christian König wrote:
>
>
> Am 05.09.22 um 18:35 schrieb Arvind Yadav:
>> Here's on debug enabling software signaling for the stub fence
>> which is always signaled. This fence should enable software
>> signaling otherwise the AMD GPU scheduler will cause a GPU reset
>> due to a GPU scheduler cleanup activity timeout.
>>
>> Signed-off-by: Arvind Yadav <Arvind.Yadav@amd.com>
>> ---
>>
>> Changes in v1 :
>> 1- Addressing Christian's comment to remove unnecessary callback.
>> 2- Replacing CONFIG_DEBUG_WW_MUTEX_SLOWPATH instead of CONFIG_DEBUG_FS.
>> 3- The version of this patch is also changed and previously
>> it was [PATCH 3/4]
>>
>> ---
>>   drivers/dma-buf/dma-fence.c | 7 +++++++
>>   1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
>> index 066400ed8841..2378b12538c4 100644
>> --- a/drivers/dma-buf/dma-fence.c
>> +++ b/drivers/dma-buf/dma-fence.c
>> @@ -27,6 +27,10 @@ EXPORT_TRACEPOINT_SYMBOL(dma_fence_signaled);
>>   static DEFINE_SPINLOCK(dma_fence_stub_lock);
>>   static struct dma_fence dma_fence_stub;
>>   +#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
>> +static bool __dma_fence_enable_signaling(struct dma_fence *fence);
>> +#endif
>> +
>
> I would rename the function to something like 
> dma_fence_enable_signaling_locked().
>
> And please don't add any #ifdef if it isn't absolutely necessary. This 
> makes the code pretty fragile.
>
>>   /*
>>    * fence context counter: each execution context should have its own
>>    * fence context, this allows checking if fences belong to the same
>> @@ -136,6 +140,9 @@ struct dma_fence *dma_fence_get_stub(void)
>>                      &dma_fence_stub_ops,
>>                      &dma_fence_stub_lock,
>>                      0, 0);
>> +#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
>> +        __dma_fence_enable_signaling(&dma_fence_stub);
>> +#endif
>
> Alternatively in this particular case you could just set the bit 
> manually here since this is part of the dma_fence code anyway.
>
> Christian.
>
As per per review comment. I will set the bit manually.

~arvind

>> dma_fence_signal_locked(&dma_fence_stub);
>>       }
>>       spin_unlock(&dma_fence_stub_lock);
>