Messages in this thread | | | Date | Mon, 21 Mar 2022 09:50:21 -0300 | From | Jason Gunthorpe <> | Subject | Re: [PATCH RFC 10/11] iommu: Make IOPF handling framework generic |
| |
On Sun, Mar 20, 2022 at 02:40:29PM +0800, Lu Baolu wrote:
> +static enum iommu_page_response_code > +iommu_sva_handle_iopf(struct iommu_fault *fault, void *data) > +{ > + vm_fault_t ret; > + struct mm_struct *mm; > + struct vm_area_struct *vma; > + unsigned int access_flags = 0; > + struct iommu_domain *domain = data;
Why is the iommu_domain not passed in as a fully typed object? I would think data should some opaque value used by non-sva cases.
What is the lifetime model here anyhow?
> + unsigned int fault_flags = FAULT_FLAG_REMOTE; > + struct iommu_fault_page_request *prm = &fault->prm; > + enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID; > + > + if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID)) > + return status; > + > + mm = domain->sva_cookie; > + if (IS_ERR_OR_NULL(mm))
Do not use this function
Do not store err pointers in structs.
> +out_put_mm: > + mmap_read_unlock(mm); > + mmput(mm);
mm structs are weird, they have two refcounts.
The 'sva_cookie' should hold a mmgrab/mmdrop() refcount to keep the pointer alive but to touch the mmap lock you have to upgrade it to a refcount that prevents destruction using mmget_not_zero() just for this short period.
Jason
| |