Re: [PATCH v2 2/8] dma-buf/dma-fence: Add dma_fence_check_and_signal()

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

On 12/1/25 16:53, Philipp Stanner wrote:
> On Mon, 2025-12-01 at 16:20 +0100, Christian König wrote:
>> On 12/1/25 14:55, Philipp Stanner wrote:
>>> On Mon, 2025-12-01 at 14:23 +0100, Christian König wrote:
>>>> On 12/1/25 11:50, Philipp Stanner wrote:
>>>>> The overwhelming majority of users of dma_fence signaling functions
>>>>> don't care about whether the fence had already been signaled by someone
>>>>>
>>>
> 
> […]
> 
>>>>
>>>>> +{
>>>>> +	unsigned long flags;
>>>>> +	bool ret;
>>>>> +
>>>>> +	spin_lock_irqsave(fence->lock, flags);
>>>>> +	ret = dma_fence_check_and_signal_locked(fence);
>>>>> +	spin_unlock_irqrestore(fence->lock, flags);
>>>>
>>>> Could this use guard(fence->lock, flags) ?
>>>
>>> guard? You mean a lockdep guard? Do you have a pointer to someplace in
>>> dma_fence who does what you mean / want?
>>
>> E.g. like guard(spinlock_irqsave)(&fence->lock);
> 
> 
> Hmm, but why?
> It's obvious to all readers that I do spin_unlock_irqrestore() here.
> It's very simple code, lock, 1 line, unlock. What would the guard
> improve?

Well you can save using the local variables.

So this:

	unsigned long flags;
	bool ret;

	spin_lock_irqsave(fence->lock, flags);
	ret = dma_fence_check_and_signal_locked(fence);
	spin_unlock_irqrestore(fence->lock, flags);

	return ret;

Becomes just:

	guard(spinlock_irqsave)(&fence->lock);
	return dma_fence_check_and_signal_locked(fence);

Regards,
Christian.

> 
> 
> P.