linux-kernel - Re: [PATCH v2] gpu: drm: udl: Adding new typedef vm_fault

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Message-ID: <CAFqt6zZeQLMkdha4DD2uMp=LOX879BrR6pf4_fwXzc3nr=G-Rw@mail.gmail.com>
Date:   Thu, 10 May 2018 19:18:46 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     airlied@...hat.com,
        Christian König <christian.koenig@....com>,
        Cihangir Aktürk <cakturk@...il.com>,
        Sean Paul <seanpaul@...omium.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Michal Hocko <mhocko@...nel.org>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH v2] gpu: drm: udl: Adding new typedef vm_fault_t

On Wed, Apr 25, 2018 at 10:29 AM, Souptick Joarder <jrdr.linux@...il.com> wrote:
> Use new return type vm_fault_t for fault and huge_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.
>
> Commit 1c8f422059ae ("mm: change return type to vm_fault_t")
>
> Previously vm_insert_page() returns err which driver
> mapped into VM_FAULT_* type. The new function vmf_
> insert_page() will replace this inefficiency by
> returning VM_FAULT_* type.
>
> Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
> Reviewed-by: Matthew Wilcox <mawilcox@...rosoft.com>
> ---
> v2: Updated the change log
>
>  drivers/gpu/drm/udl/udl_drv.h |  3 ++-
>  drivers/gpu/drm/udl/udl_gem.c | 15 ++-------------
>  2 files changed, 4 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/udl/udl_drv.h b/drivers/gpu/drm/udl/udl_drv.h
> index 2a75ab8..11151c4 100644
> --- a/drivers/gpu/drm/udl/udl_drv.h
> +++ b/drivers/gpu/drm/udl/udl_drv.h
> @@ -16,6 +16,7 @@
>
>  #include <linux/usb.h>
>  #include <drm/drm_gem.h>
> +#include <linux/mm_types.h>
>
>  #define DRIVER_NAME            "udl"
>  #define DRIVER_DESC            "DisplayLink"
> @@ -134,7 +135,7 @@ struct drm_gem_object *udl_gem_prime_import(struct drm_device *dev,
>  int udl_gem_vmap(struct udl_gem_object *obj);
>  void udl_gem_vunmap(struct udl_gem_object *obj);
>  int udl_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma);
> -int udl_gem_fault(struct vm_fault *vmf);
> +vm_fault_t udl_gem_fault(struct vm_fault *vmf);
>
>  int udl_handle_damage(struct udl_framebuffer *fb, int x, int y,
>                       int width, int height);
> diff --git a/drivers/gpu/drm/udl/udl_gem.c b/drivers/gpu/drm/udl/udl_gem.c
> index dee6bd9..cf5fe35 100644
> --- a/drivers/gpu/drm/udl/udl_gem.c
> +++ b/drivers/gpu/drm/udl/udl_gem.c
> @@ -100,13 +100,12 @@ int udl_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
>         return ret;
>  }
>
> -int udl_gem_fault(struct vm_fault *vmf)
> +vm_fault_t udl_gem_fault(struct vm_fault *vmf)
>  {
>         struct vm_area_struct *vma = vmf->vma;
>         struct udl_gem_object *obj = to_udl_bo(vma->vm_private_data);
>         struct page *page;
>         unsigned int page_offset;
> -       int ret = 0;
>
>         page_offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT;
>
> @@ -114,17 +113,7 @@ int udl_gem_fault(struct vm_fault *vmf)
>                 return VM_FAULT_SIGBUS;
>
>         page = obj->pages[page_offset];
> -       ret = vm_insert_page(vma, vmf->address, page);
> -       switch (ret) {
> -       case -EAGAIN:
> -       case 0:
> -       case -ERESTARTSYS:
> -               return VM_FAULT_NOPAGE;
> -       case -ENOMEM:
> -               return VM_FAULT_OOM;
> -       default:
> -               return VM_FAULT_SIGBUS;
> -       }
> +       return vmf_insert_page(vma, vmf->address, page);
>  }
>
>  int udl_gem_get_pages(struct udl_gem_object *obj)
> --
> 1.9.1
>

Any comment on this patch ?