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authorKirti Wankhede <kwankhede@nvidia.com>2020-05-28 23:30:48 +0300
committerAlex Williamson <alex.williamson@redhat.com>2020-05-29 00:53:21 +0300
commit6581708586c812460ea4798216d9dd2897ad105c (patch)
treebb47b15b72e57676769c1cd908a5129b73b271b6 /drivers/vfio
parenta8a24f3f6e38103b77cf399c38eb54e1219d00d6 (diff)
downloadlinux-6581708586c812460ea4798216d9dd2897ad105c.tar.xz
vfio iommu: Remove atomicity of ref_count of pinned pages
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>
Diffstat (limited to 'drivers/vfio')
-rw-r--r--drivers/vfio/vfio_iommu_type1.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 4a4cb7cd86b2..e0de3337fa2a 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -112,7 +112,7 @@ struct vfio_pfn {
struct rb_node node;
dma_addr_t iova; /* Device address */
unsigned long pfn; /* Host pfn */
- atomic_t ref_count;
+ unsigned int ref_count;
};
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->pfn = pfn;
- atomic_set(&vpfn->ref_count, 1);
+ vpfn->ref_count = 1;
vfio_link_pfn(dma, vpfn);
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);
if (vpfn)
- atomic_inc(&vpfn->ref_count);
+ vpfn->ref_count++;
return vpfn;
}
@@ -259,7 +259,8 @@ static int vfio_iova_put_vfio_pfn(struct vfio_dma *dma, struct vfio_pfn *vpfn)
{
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);
vfio_remove_from_pfn_list(dma, vpfn);
}