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

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

On Thu, Apr 09, 2020 at 05:07:34PM +0800, Zhangfei Gao wrote:
> 
> 
> 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@linaro.org>
> Thanks Jean for doing this.
> 
> Tested-by: Zhangfei Gao <zhangfei.gao@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, I'll add it in v2

Jean
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