RE: [PATCH v2 06/12] iommu/vt-d: Acquiring lock in domain ID allocation helpers

[Tian, Kevin]

> From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Sent: Tuesday, June 14, 2022 10:52 AM
> 
> The iommu->lock is used to protect the per-IOMMU domain ID resource.
> Moving the lock into the ID alloc/free helpers makes the code more
> compact. At the same time, the device_domain_lock is irrelevant to
> the domain ID resource, remove its assertion as well.
> 
> On the other hand, the iommu->lock is never used in interrupt context,
> there's no need to use the irqsave variant of the spinlock calls.

I still prefer to separating reduction of lock ranges from changing irqsave.
Locking is tricky. From bisect p.o.v. it will be a lot easier if we just change
one logic in one patch.