Re: [PATCH 1/4] dma-buf: Check status of enable-signaling bit on debug

Yadav, Arvind
2022-09-05T13:44:11Z

On 9/5/2022 4:51 PM, Christian König wrote:
> Am 05.09.22 um 12:56 schrieb Arvind Yadav:
>> The core DMA-buf framework needs to enable signaling
>> before the fence is signaled. The core DMA-buf framework
>> can forget to enable signaling before the fence is signaled.
>> To avoid this scenario on the debug kernel, check the
>> DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT status bit before checking
>> the signaling bit status to confirm that enable_signaling
>> is enabled.
>
> You might want to put this patch at the end of the series to avoid
> breaking the kernel in between.
>
sure, I will add this patch at end.
>>
>> Signed-off-by: Arvind Yadav <Arvind.Yadav@amd.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..60c0e935c0b5 100644
>> --- a/include/linux/dma-fence.h
>> +++ b/include/linux/dma-fence.h
>> @@ -428,6 +428,11 @@ dma_fence_is_signaled_locked(struct dma_fence
>> *fence)
>>   static inline bool
>>   dma_fence_is_signaled(struct dma_fence *fence)
>>   {
>> +#ifdef CONFIG_DEBUG_FS
>
> CONFIG_DEBUG_FS is certainly wrong, probably better to check for
> CONFIG_DEBUG_WW_MUTEX_SLOWPATH here.
>
> Apart from that looks good to me,
> Christian.
>
I will use CONFIG_DEBUG_WW_MUTEX_SLOWPATH instead of CONFIG_DEBUG_FS

~arvind

>> +    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;
>