Messages in this thread | | | Date | Tue, 22 Mar 2022 12:50:45 +0800 | Subject | Re: [PATCH RFC 09/11] iommu: Add iommu_get_domain_for_dev_pasid() | From | Lu Baolu <> |
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On 2022/3/21 20:40, Jason Gunthorpe wrote: > On Sun, Mar 20, 2022 at 02:40:28PM +0800, Lu Baolu wrote: >> @@ -3098,7 +3101,16 @@ int iommu_attach_device_pasid(struct iommu_domain *domain, >> if (iommu_group_device_count(group) != 1) >> goto out_unlock; >> >> + xa_lock(&group->pasid_array); >> + curr = __xa_cmpxchg(&group->pasid_array, pasid, NULL, >> + domain, GFP_KERNEL); >> + xa_unlock(&group->pasid_array); >> + if (curr) > > curr can be an xa_err that should be propogated.
Yes, should check xa_err().
> >> + goto out_unlock; >> + >> ret = domain->ops->attach_dev_pasid(domain, dev, pasid); >> + if (ret) >> + xa_erase(&group->pasid_array, pasid); >> >> out_unlock: >> mutex_unlock(&group->mutex); >> @@ -3118,6 +3130,25 @@ void iommu_detach_device_pasid(struct iommu_domain *domain, >> >> mutex_lock(&group->mutex); >> domain->ops->detach_dev_pasid(domain, dev, pasid); >> + xa_erase(&group->pasid_array, pasid); >> + mutex_unlock(&group->mutex); >> + iommu_group_put(group); >> +} >> + >> +struct iommu_domain * >> +iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid) >> +{ >> + struct iommu_domain *domain; >> + struct iommu_group *group; >> + >> + group = iommu_group_get(dev); >> + if (!group) >> + return NULL; >> + >> + mutex_lock(&group->mutex); >> + domain = xa_load(&group->pasid_array, pasid); >> mutex_unlock(&group->mutex); >> iommu_group_put(group); > > This whole API seems sketchy - what is the lifecycle of the returned > iommu_domain and what prevents it from being concurrently freed after > unlocking?
Agreed. The domain could be used in page fault handling thread, hence need a mechanism to guarantee the concurrence.
Best regards, baolu
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