[PATCH 1/2] uacce: Remove mm_exit() op

[Zhangfei Gao]

On 2020/4/8 下午10:04, Jean-Philippe Brucker wrote:
> The mm_exit() op will be removed from the SVA API. When a process dies
> and its mm goes away, the IOMMU driver won't notify device drivers
> anymore. Drivers should expect to handle a lot more aborted DMA. On the
> upside, it does greatly simplify the queue management.
>
> The uacce_mm struct, that tracks all queues bound to an mm, was only
> used by the mm_exit() callback. Remove it.
>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe at linaro.org>
Thanks Jean for doing this.

Tested-by: Zhangfei Gao <zhangfei.gao at linaro.org>

Except one line.
> -static void uacce_mm_put(struct uacce_queue *q)
> +static void uacce_unbind_queue(struct uacce_queue *q)
>   {
> -	struct uacce_mm *uacce_mm = q->uacce_mm;
> -
> -	lockdep_assert_held(&q->uacce->mm_lock);
> -
> -	mutex_lock(&uacce_mm->lock);
> -	list_del(&q->list);
> -	mutex_unlock(&uacce_mm->lock);
> -
> -	if (list_empty(&uacce_mm->queues)) {
> -		if (uacce_mm->handle)
> -			iommu_sva_unbind_device(uacce_mm->handle);
> -		list_del(&uacce_mm->list);
> -		kfree(uacce_mm);
> -	}
> +	if (!q->handle)
> +		return;
> +	iommu_sva_unbind_device(q->handle);
+ q->handle = 0;

Otherwise iommu_sva_unbind_device maybe called twice.
Since uacce_unbind_queue can be called by uacce_remove and uacce_fops_release.

Thanks