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

Daniel Vetter
2018-05-16T09:53:12Z

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
>

--
Daniel Vetter
Software Engineer, Intel Corporation