Re: [PATCH 07/12] iommu/vt-d: Acquiring lock in pasid manipulation helpers

[Baolu Lu]

On 2022/6/1 17:18, Tian, Kevin wrote:
> > From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > Sent: Friday, May 27, 2022 2:30 PM
> >
> > The iommu->lock is used to protect the per-IOMMU pasid directory table
> > and pasid table. Move the spinlock acquisition/release into the helpers
> > to make the code self-contained.
> >
> > Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
>
> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>, with one nit
>
> > -	/* Caller must ensure PASID entry is not in use. */
> > -	if (pasid_pte_is_present(pte))
> > -		return -EBUSY;
> > +	spin_lock(&iommu->lock);
> > +	pte = get_non_present_pasid_entry(dev, pasid);
> > +	if (!pte) {
> > +		spin_unlock(&iommu->lock);
> > +		return -ENODEV;
> > +	}
>
> I don't think above is a good abstraction and it changes the error
> code for an present entry from -EBUSY to -ENODEV.

Sure. I will roll it back to -EBUSY. I added this helper because the
same code appears at least three times in this file.

Best regards,
baolu