Re: [PATCH v3] gpu: drm: gma500: Change return type to vm_fault_t

[Souptick Joarder]

On Sun, May 27, 2018 at 6:15 AM, Souptick Joarder <jrdr.linux@xxxxxxxxx> wrote:
> Use new return type vm_fault_t for fault handler. For
> now, this is just documenting that the function returns
> a VM_FAULT value rather than an errno. Once all instances
> are converted, vm_fault_t will become a distinct type.
>
> Ref-> commit 1c8f422059ae ("mm: change return type to vm_fault_t")
>
> Previously vm_insert_{pfn,mixed} returns err which driver
> mapped into VM_FAULT_* type. The new function
> vmf_insert_{pfn,mixed} will replace this inefficiency by
> returning VM_FAULT_* type.
>
> vmf_error() is the newly introduce inline function
> in 4.17-rc6.
>
> Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx>
> Reviewed-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
> ---
> v2: updated the change log
>
> v3: Fixed kbuild error
>
>  drivers/gpu/drm/gma500/framebuffer.c | 14 +++++---------
>  drivers/gpu/drm/gma500/gem.c         | 27 ++++++++++-----------------
>  drivers/gpu/drm/gma500/psb_drv.h     |  3 ++-
>  3 files changed, 17 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/gpu/drm/gma500/framebuffer.c b/drivers/gpu/drm/gma500/framebuffer.c
> index cb0a2ae..632aadb 100644
> --- a/drivers/gpu/drm/gma500/framebuffer.c
> +++ b/drivers/gpu/drm/gma500/framebuffer.c
> @@ -111,7 +111,7 @@ static int psbfb_pan(struct fb_var_screeninfo *var, struct fb_info *info)
>          return 0;
>  }
>
> -static int psbfb_vm_fault(struct vm_fault *vmf)
> +static vm_fault_t psbfb_vm_fault(struct vm_fault *vmf)
>  {
>         struct vm_area_struct *vma = vmf->vma;
>         struct psb_framebuffer *psbfb = vma->vm_private_data;
> @@ -120,7 +120,7 @@ static int psbfb_vm_fault(struct vm_fault *vmf)
>         int page_num;
>         int i;
>         unsigned long address;
> -       int ret;
> +       vm_fault_t ret = VM_FAULT_SIGBUS;
>         unsigned long pfn;
>         unsigned long phys_addr = (unsigned long)dev_priv->stolen_base +
>                                   psbfb->gtt->offset;
> @@ -133,18 +133,14 @@ static int psbfb_vm_fault(struct vm_fault *vmf)
>         for (i = 0; i < page_num; i++) {
>                 pfn = (phys_addr >> PAGE_SHIFT);
>
> -               ret = vm_insert_mixed(vma, address,
> +               ret = vmf_insert_mixed(vma, address,
>                                 __pfn_to_pfn_t(pfn, PFN_DEV));
> -               if (unlikely((ret == -EBUSY) || (ret != 0 && i > 0)))
> +               if (unlikely(ret & VM_FAULT_ERROR))
>                         break;
> -               else if (unlikely(ret != 0)) {
> -                       ret = (ret == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS;
> -                       return ret;
> -               }
>                 address += PAGE_SIZE;
>                 phys_addr += PAGE_SIZE;
>         }
> -       return VM_FAULT_NOPAGE;
> +       return ret;
>  }
>
>  static void psbfb_vm_open(struct vm_area_struct *vma)
> diff --git a/drivers/gpu/drm/gma500/gem.c b/drivers/gpu/drm/gma500/gem.c
> index 1312397..e7be5c9 100644
> --- a/drivers/gpu/drm/gma500/gem.c
> +++ b/drivers/gpu/drm/gma500/gem.c
> @@ -134,12 +134,13 @@ int psb_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
>   *     vma->vm_private_data points to the GEM object that is backing this
>   *     mapping.
>   */
> -int psb_gem_fault(struct vm_fault *vmf)
> +vm_fault_t psb_gem_fault(struct vm_fault *vmf)
>  {
>         struct vm_area_struct *vma = vmf->vma;
>         struct drm_gem_object *obj;
>         struct gtt_range *r;
> -       int ret;
> +       int err;
> +       vm_fault_t ret;
>         unsigned long pfn;
>         pgoff_t page_offset;
>         struct drm_device *dev;
> @@ -158,9 +159,10 @@ int psb_gem_fault(struct vm_fault *vmf)
>         /* For now the mmap pins the object and it stays pinned. As things
>            stand that will do us no harm */
>         if (r->mmapping == 0) {
> -               ret = psb_gtt_pin(r);
> -               if (ret < 0) {
> -                       dev_err(dev->dev, "gma500: pin failed: %d\n", ret);
> +               err = psb_gtt_pin(r);
> +               if (err < 0) {
> +                       dev_err(dev->dev, "gma500: pin failed: %d\n", err);
> +                       ret = vmf_error(err);
>                         goto fail;
>                 }
>                 r->mmapping = 1;
> @@ -175,18 +177,9 @@ int psb_gem_fault(struct vm_fault *vmf)
>                 pfn = (dev_priv->stolen_base + r->offset) >> PAGE_SHIFT;
>         else
>                 pfn = page_to_pfn(r->pages[page_offset]);
> -       ret = vm_insert_pfn(vma, vmf->address, pfn);
> -
> +       ret = vmf_insert_pfn(vma, vmf->address, pfn);
>  fail:
>         mutex_unlock(&dev_priv->mmap_mutex);
> -       switch (ret) {
> -       case 0:
> -       case -ERESTARTSYS:
> -       case -EINTR:
> -               return VM_FAULT_NOPAGE;
> -       case -ENOMEM:
> -               return VM_FAULT_OOM;
> -       default:
> -               return VM_FAULT_SIGBUS;
> -       }
> +
> +       return ret;
>  }
> diff --git a/drivers/gpu/drm/gma500/psb_drv.h b/drivers/gpu/drm/gma500/psb_drv.h
> index e8300f5..93d2f40 100644
> --- a/drivers/gpu/drm/gma500/psb_drv.h
> +++ b/drivers/gpu/drm/gma500/psb_drv.h
> @@ -21,6 +21,7 @@
>  #define _PSB_DRV_H_
>
>  #include <linux/kref.h>
> +#include <linux/mm_types.h>
>
>  #include <drm/drmP.h>
>  #include <drm/drm_global.h>
> @@ -749,7 +750,7 @@ extern int psb_gem_get_aperture(struct drm_device *dev, void *data,
>                         struct drm_file *file);
>  extern int psb_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
>                         struct drm_mode_create_dumb *args);
> -extern int psb_gem_fault(struct vm_fault *vmf);
> +extern vm_fault_t psb_gem_fault(struct vm_fault *vmf);
>
>  /* psb_device.c */
>  extern const struct psb_ops psb_chip_ops;
> --
> 1.9.1
>

If no comment, we would like to get this patch
in 4.18.