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vfio iommu: Remove atomicity of ref_count of pinned pages

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vfio_pfn.ref_count is always updated while holding iommu->lock, using
atomic variable is overkill.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Kirti Wankhede
2020-05-29 02:00:48 +05:30
committed by Alex Williamson
parent a8a24f3f6e
commit 6581708586
1 changed files with 5 additions and 4 deletions
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9
drivers/vfio/vfio_iommu_type1.c
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@@ -112,7 +112,7 @@ struct vfio_pfn {
struct rb_node node; struct rb_node node;
dma_addr_t iova; /* Device address */ dma_addr_t iova; /* Device address */
unsigned long pfn; /* Host pfn */ unsigned long pfn; /* Host pfn */
atomic_t ref_count; unsigned int ref_count;
}; };
struct vfio_regions { struct vfio_regions {
@@ -233,7 +233,7 @@ static int vfio_add_to_pfn_list(struct vfio_dma *dma, dma_addr_t iova,
vpfn->iova = iova; vpfn->iova = iova;
vpfn->pfn = pfn; vpfn->pfn = pfn;
atomic_set(&vpfn->ref_count, 1); vpfn->ref_count = 1;
vfio_link_pfn(dma, vpfn); vfio_link_pfn(dma, vpfn);
return 0; return 0;
} }
@@ -251,7 +251,7 @@ static struct vfio_pfn *vfio_iova_get_vfio_pfn(struct vfio_dma *dma,
struct vfio_pfn *vpfn = vfio_find_vpfn(dma, iova); struct vfio_pfn *vpfn = vfio_find_vpfn(dma, iova);
if (vpfn) if (vpfn)
atomic_inc(&vpfn->ref_count); vpfn->ref_count++;
return vpfn; return vpfn;
} }
@@ -259,7 +259,8 @@ static int vfio_iova_put_vfio_pfn(struct vfio_dma *dma, struct vfio_pfn *vpfn)
{ {
int ret = 0; int ret = 0;
if (atomic_dec_and_test(&vpfn->ref_count)) { vpfn->ref_count--;
if (!vpfn->ref_count) {
ret = put_pfn(vpfn->pfn, dma->prot); ret = put_pfn(vpfn->pfn, dma->prot);
vfio_remove_from_pfn_list(dma, vpfn); vfio_remove_from_pfn_list(dma, vpfn);
} }