Re: [PATCH v16 Kernel 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages

2020-03-26 Thread Kirti Wankhede 




On 3/26/2020 4:19 PM, Cornelia Huck wrote:

On Wed, 25 Mar 2020 01:02:34 +0530
Kirti Wankhede  wrote:


vfio_pfn.ref_count is always updated by holding iommu->lock, using atomic


s/by/while/



Ok.


variable is overkill.

Signed-off-by: Kirti Wankhede 
Reviewed-by: Neo Jia 
Reviewed-by: Eric Auger 
---
  drivers/vfio/vfio_iommu_type1.c | 9 +
  1 file changed, 5 insertions(+), 4 deletions(-)



Reviewed-by: Cornelia Huck 



Thanks,
Kirti

Re: [PATCH v16 Kernel 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages

2020-03-26 Thread Cornelia Huck 
On Wed, 25 Mar 2020 01:02:34 +0530
Kirti Wankhede  wrote:

> vfio_pfn.ref_count is always updated by holding iommu->lock, using atomic

s/by/while/

> variable is overkill.
> 
> Signed-off-by: Kirti Wankhede 
> Reviewed-by: Neo Jia 
> Reviewed-by: Eric Auger 
> ---
>  drivers/vfio/vfio_iommu_type1.c | 9 +
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 

Reviewed-by: Cornelia Huck

[PATCH v16 Kernel 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages

2020-03-24 Thread Kirti Wankhede 
vfio_pfn.ref_count is always updated by holding iommu->lock, using atomic
variable is overkill.

Signed-off-by: Kirti Wankhede 
Reviewed-by: Neo Jia 
Reviewed-by: Eric Auger 
---
 drivers/vfio/vfio_iommu_type1.c | 9 +
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 9fdfae1cb17a..70aeab921d0f 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_tref_count;
+   unsigned intref_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(>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(>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(>ref_count)) {
+   vpfn->ref_count--;
+   if (!vpfn->ref_count) {
ret = put_pfn(vpfn->pfn, dma->prot);
vfio_remove_from_pfn_list(dma, vpfn);
}
-- 
2.7.0