[10/14] vgem: separate errno from VM_FAULT_* values

Message ID 20180516054348.15950-11-hch@lst.de
State Not Applicable, archived
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Series
  • Untitled series #44596
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Commit Message

Christoph Hellwig May 16, 2018, 5:43 a.m.
And streamline the code in vgem_fault with early returns so that it is
a little bit more readable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/gpu/drm/vgem/vgem_drv.c | 51 +++++++++++++++------------------
 1 file changed, 23 insertions(+), 28 deletions(-)

Comments

Daniel Vetter May 16, 2018, 9:53 a.m. | #1
On Wed, May 16, 2018 at 07:43:44AM +0200, Christoph Hellwig wrote:
> And streamline the code in vgem_fault with early returns so that it is
> a little bit more readable.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/gpu/drm/vgem/vgem_drv.c | 51 +++++++++++++++------------------
>  1 file changed, 23 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> index 2524ff116f00..a261e0aab83a 100644
> --- a/drivers/gpu/drm/vgem/vgem_drv.c
> +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> @@ -61,12 +61,13 @@ static void vgem_gem_free_object(struct drm_gem_object *obj)
>  	kfree(vgem_obj);
>  }
>  
> -static int vgem_gem_fault(struct vm_fault *vmf)
> +static vm_fault_t vgem_gem_fault(struct vm_fault *vmf)
>  {
>  	struct vm_area_struct *vma = vmf->vma;
>  	struct drm_vgem_gem_object *obj = vma->vm_private_data;
>  	/* We don't use vmf->pgoff since that has the fake offset */
>  	unsigned long vaddr = vmf->address;
> +	struct page *page;
>  	int ret;
>  	loff_t num_pages;
>  	pgoff_t page_offset;
> @@ -85,35 +86,29 @@ static int vgem_gem_fault(struct vm_fault *vmf)
>  		ret = 0;
>  	}
>  	mutex_unlock(&obj->pages_lock);
> -	if (ret) {
> -		struct page *page;
> -
> -		page = shmem_read_mapping_page(
> -					file_inode(obj->base.filp)->i_mapping,
> -					page_offset);
> -		if (!IS_ERR(page)) {
> -			vmf->page = page;
> -			ret = 0;
> -		} else switch (PTR_ERR(page)) {
> -			case -ENOSPC:
> -			case -ENOMEM:
> -				ret = VM_FAULT_OOM;
> -				break;
> -			case -EBUSY:
> -				ret = VM_FAULT_RETRY;
> -				break;
> -			case -EFAULT:
> -			case -EINVAL:
> -				ret = VM_FAULT_SIGBUS;
> -				break;
> -			default:
> -				WARN_ON(PTR_ERR(page));
> -				ret = VM_FAULT_SIGBUS;
> -				break;
> -		}
> +	if (!ret)
> +		return 0;
> +
> +	page = shmem_read_mapping_page(file_inode(obj->base.filp)->i_mapping,
> +			page_offset);
> +	if (!IS_ERR(page)) {
> +		vmf->page = page;
> +		return 0;
> +	}
>  
> +	switch (PTR_ERR(page)) {
> +	case -ENOSPC:
> +	case -ENOMEM:
> +		return VM_FAULT_OOM;
> +	case -EBUSY:
> +		return VM_FAULT_RETRY;
> +	case -EFAULT:
> +	case -EINVAL:
> +		return VM_FAULT_SIGBUS;
> +	default:
> +		WARN_ON(PTR_ERR(page));
> +		return VM_FAULT_SIGBUS;
>  	}
> -	return ret;

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Want me to merge this through drm-misc or plan to pick it up yourself?
-Daniel

>  }
>  
>  static const struct vm_operations_struct vgem_gem_vm_ops = {
> -- 
> 2.17.0
>
Christoph Hellwig May 16, 2018, 1:01 p.m. | #2
On Wed, May 16, 2018 at 11:53:03AM +0200, Daniel Vetter wrote:
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> Want me to merge this through drm-misc or plan to pick it up yourself?

For now I just want a honest discussion if people really actually
want the vm_fault_t change with the whole picture in place.
Matthew Wilcox May 16, 2018, 1:13 p.m. | #3
On Wed, May 16, 2018 at 03:01:59PM +0200, Christoph Hellwig wrote:
> On Wed, May 16, 2018 at 11:53:03AM +0200, Daniel Vetter wrote:
> > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> > 
> > Want me to merge this through drm-misc or plan to pick it up yourself?
> 
> For now I just want a honest discussion if people really actually
> want the vm_fault_t change with the whole picture in place.

That discussion already happened on the -mm mailing list.  And again
at LSFMM.  Both times the answer was yes.

Patch

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 2524ff116f00..a261e0aab83a 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -61,12 +61,13 @@  static void vgem_gem_free_object(struct drm_gem_object *obj)
 	kfree(vgem_obj);
 }
 
-static int vgem_gem_fault(struct vm_fault *vmf)
+static vm_fault_t vgem_gem_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct drm_vgem_gem_object *obj = vma->vm_private_data;
 	/* We don't use vmf->pgoff since that has the fake offset */
 	unsigned long vaddr = vmf->address;
+	struct page *page;
 	int ret;
 	loff_t num_pages;
 	pgoff_t page_offset;
@@ -85,35 +86,29 @@  static int vgem_gem_fault(struct vm_fault *vmf)
 		ret = 0;
 	}
 	mutex_unlock(&obj->pages_lock);
-	if (ret) {
-		struct page *page;
-
-		page = shmem_read_mapping_page(
-					file_inode(obj->base.filp)->i_mapping,
-					page_offset);
-		if (!IS_ERR(page)) {
-			vmf->page = page;
-			ret = 0;
-		} else switch (PTR_ERR(page)) {
-			case -ENOSPC:
-			case -ENOMEM:
-				ret = VM_FAULT_OOM;
-				break;
-			case -EBUSY:
-				ret = VM_FAULT_RETRY;
-				break;
-			case -EFAULT:
-			case -EINVAL:
-				ret = VM_FAULT_SIGBUS;
-				break;
-			default:
-				WARN_ON(PTR_ERR(page));
-				ret = VM_FAULT_SIGBUS;
-				break;
-		}
+	if (!ret)
+		return 0;
+
+	page = shmem_read_mapping_page(file_inode(obj->base.filp)->i_mapping,
+			page_offset);
+	if (!IS_ERR(page)) {
+		vmf->page = page;
+		return 0;
+	}
 
+	switch (PTR_ERR(page)) {
+	case -ENOSPC:
+	case -ENOMEM:
+		return VM_FAULT_OOM;
+	case -EBUSY:
+		return VM_FAULT_RETRY;
+	case -EFAULT:
+	case -EINVAL:
+		return VM_FAULT_SIGBUS;
+	default:
+		WARN_ON(PTR_ERR(page));
+		return VM_FAULT_SIGBUS;
 	}
-	return ret;
 }
 
 static const struct vm_operations_struct vgem_gem_vm_ops = {