Re: [PATCH 2/8] dma-buf: detach fence ops on signal v2

["Christian König" <christian.koenig@amd.com>]

On 2/13/26 15:22, Boris Brezillon wrote:
>> ---
>>  drivers/dma-buf/dma-fence.c | 16 ++++++++++++----
>>  include/linux/dma-fence.h   |  4 ++--
>>  2 files changed, 14 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
>> index de9bf18be3d4..ba02321bef0b 100644
>> --- a/drivers/dma-buf/dma-fence.c
>> +++ b/drivers/dma-buf/dma-fence.c
>> @@ -371,6 +371,14 @@ void dma_fence_signal_timestamp_locked(struct dma_fence *fence,
>>  				      &fence->flags)))
>>  		return;
>>  
>> +	/*
>> +	 * When neither a release nor a wait operation is specified set the ops
>> +	 * pointer to NULL to allow the fence structure to become independent
>> +	 * from who originally issued it.
> 
> I think this deserves some comment in the dma_fence_ops doc, so that
> people know what to expect when they implement this interface.
There was already a warning added like ~5years ago that implementations shouldn't use the wait callback.

Completely independent of this patch set here we already had tons of trouble with it because it can't take into account when userpsace waits for multiple fences from different implementations.

It potentially was never a good idea to have in the first place, we basically only had it because radeon (and IIRC nouveau at that point) depended on it.

Regards,
Christian.