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

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Date:   Wed, 23 May 2018 10:49:04 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Souptick Joarder <jrdr.linux@...il.com>
Cc:     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>,
        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 Mon, May 21, 2018 at 10:27:44AM +0530, Souptick Joarder wrote:
> On Thu, May 10, 2018 at 7:18 PM, Souptick Joarder <jrdr.linux@...il.com> wrote:
> > 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 ?
> 
> If no comment, we would like to get this patch in queue
> for 4.18.

4.18 is done already, queued up for 4.19 in drm-misc-next.

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch