Re: [PATCH v1 2/6] iommu/vt-d: Use IDA interface to manage iommu sequence id

[Lu Baolu]

On 6/30/22 4:21 PM, Tian, Kevin wrote:
> > From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > Sent: Saturday, June 25, 2022 8:52 PM
> >
> > @@ -1062,11 +1040,14 @@ static int alloc_iommu(struct dmar_drhd_unit
> > *drhd)
> >   	if (!iommu)
> >   		return -ENOMEM;
> >
> > -	if (dmar_alloc_seq_id(iommu) < 0) {
> > +	iommu->seq_id = ida_alloc_range(&dmar_seq_ids, 0,
> > +					DMAR_UNITS_SUPPORTED,
>
> should be "DMAR_UNITS_SUPPORTED - 1"

Yes, according to "@max: Highest ID to allocate.". Updated.

> > GFP_KERNEL);
> > +	if (iommu->seq_id < 0) {
> >   		pr_err("Failed to allocate seq_id\n");
> >   		err = -ENOSPC;
> >   		goto error;
> >   	}
>
> ida_alloc_range() returns error code already. No need to change it.

Agreed. Updated as below:

diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
index bf43889b9d2a..6327b34f5aa7 100644
--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -1041,10 +1041,10 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
                return -ENOMEM;

        iommu->seq_id = ida_alloc_range(&dmar_seq_ids, 0,
-                                       DMAR_UNITS_SUPPORTED, GFP_KERNEL);
+                                       DMAR_UNITS_SUPPORTED - 1, 
GFP_KERNEL);
        if (iommu->seq_id < 0) {
                pr_err("Failed to allocate seq_id\n");
-               err = -ENOSPC;
+               err = iommu->seq_id;
                goto error;
        }
        sprintf(iommu->name, "dmar%d", iommu->seq_id);

Best regards,
baolu