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

[Rob Clark <robdclark-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Sun, Jun 17, 2018 at 11:40 PM, Souptick Joarder <jrdr.linux@gmail.com> wrote:
> On Thu, May 31, 2018 at 11:29 PM, Jordan Crouse <jcrouse@codeaurora.org> wrote:
>> On Mon, May 28, 2018 at 12:38:41PM +0530, Souptick Joarder wrote:
>>> On Mon, May 21, 2018 at 10:59 PM, Souptick Joarder <jrdr.linux@gmail.com> 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_mixed() returns err which driver
>>> > mapped into VM_FAULT_* type. The new function
>>> > vmf_insert_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@gmail.com>
>>> > Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
>>> > ---
>>> >  drivers/gpu/drm/msm/msm_drv.h |  3 ++-
>>> >  drivers/gpu/drm/msm/msm_gem.c | 33 ++++++++++-----------------------
>>> >  2 files changed, 12 insertions(+), 24 deletions(-)
>>> >
>>> > diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
>>> > index 0a653dd..44b4ca7 100644
>>> > --- a/drivers/gpu/drm/msm/msm_drv.h
>>> > +++ b/drivers/gpu/drm/msm/msm_drv.h
>>> > @@ -33,6 +33,7 @@
>>> >  #include <linux/of_graph.h>
>>> >  #include <linux/of_device.h>
>>> >  #include <asm/sizes.h>
>>> > +#include <linux/mm_types.h>
>>> >
>>> >  #include <drm/drmP.h>
>>> >  #include <drm/drm_atomic.h>
>>> > @@ -188,7 +189,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
>>> >  int msm_gem_mmap_obj(struct drm_gem_object *obj,
>>> >                         struct vm_area_struct *vma);
>>> >  int msm_gem_mmap(struct file *filp, struct vm_area_struct *vma);
>>> > -int msm_gem_fault(struct vm_fault *vmf);
>>> > +vm_fault_t msm_gem_fault(struct vm_fault *vmf);
>>> >  uint64_t msm_gem_mmap_offset(struct drm_gem_object *obj);
>>> >  int msm_gem_get_iova(struct drm_gem_object *obj,
>>> >                 struct msm_gem_address_space *aspace, uint64_t *iova);
>>> > diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
>>> > index 07376de..27a5ab5 100644
>>> > --- a/drivers/gpu/drm/msm/msm_gem.c
>>> > +++ b/drivers/gpu/drm/msm/msm_gem.c
>>> > @@ -217,7 +217,7 @@ int msm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
>>> >         return msm_gem_mmap_obj(vma->vm_private_data, vma);
>>> >  }
>>> >
>>> > -int msm_gem_fault(struct vm_fault *vmf)
>>> > +vm_fault_t msm_gem_fault(struct vm_fault *vmf)
>>> >  {
>>> >         struct vm_area_struct *vma = vmf->vma;
>>> >         struct drm_gem_object *obj = vma->vm_private_data;
>>> > @@ -225,15 +225,18 @@ int msm_gem_fault(struct vm_fault *vmf)
>>> >         struct page **pages;
>>> >         unsigned long pfn;
>>> >         pgoff_t pgoff;
>>> > -       int ret;
>>> > +       int err;
>>> > +       vm_fault_t ret;
>>> >
>>> >         /*
>>> >          * vm_ops.open/drm_gem_mmap_obj and close get and put
>>> >          * a reference on obj. So, we dont need to hold one here.
>>> >          */
>>> > -       ret = mutex_lock_interruptible(&msm_obj->lock);
>>> > -       if (ret)
>>> > +       err = mutex_lock_interruptible(&msm_obj->lock);
>>> > +       if (err) {
>>> > +               ret = VM_FAULT_NOPAGE;
>>> >                 goto out;
>>> > +       }
>>> >
>>> >         if (WARN_ON(msm_obj->madv != MSM_MADV_WILLNEED)) {
>>> >                 mutex_unlock(&msm_obj->lock);
>>> > @@ -243,7 +246,7 @@ int msm_gem_fault(struct vm_fault *vmf)
>>> >         /* make sure we have pages attached now */
>>> >         pages = get_pages(obj);
>>> >         if (IS_ERR(pages)) {
>>> > -               ret = PTR_ERR(pages);
>>> > +               ret = vmf_error(PTR_ERR(pages));
>>> >                 goto out_unlock;
>>> >         }
>>> >
>>> > @@ -255,27 +258,11 @@ int msm_gem_fault(struct vm_fault *vmf)
>>> >         VERB("Inserting %p pfn %lx, pa %lx", (void *)vmf->address,
>>> >                         pfn, pfn << PAGE_SHIFT);
>>> >
>>> > -       ret = vm_insert_mixed(vma, vmf->address, __pfn_to_pfn_t(pfn, PFN_DEV));
>>> > -
>>> > +       ret = vmf_insert_mixed(vma, vmf->address, __pfn_to_pfn_t(pfn, PFN_DEV));
>>> >  out_unlock:
>>> >         mutex_unlock(&msm_obj->lock);
>>> >  out:
>>> > -       switch (ret) {
>>> > -       case -EAGAIN:
>>> > -       case 0:
>>> > -       case -ERESTARTSYS:
>>> > -       case -EINTR:
>>> > -       case -EBUSY:
>>> > -               /*
>>> > -                * EBUSY is ok: this just means that another thread
>>> > -                * already did the job.
>>> > -                */
>>> > -               return VM_FAULT_NOPAGE;
>>> > -       case -ENOMEM:
>>> > -               return VM_FAULT_OOM;
>>> > -       default:
>>> > -               return VM_FAULT_SIGBUS;
>>> > -       }
>>> > +       return ret;
>>> >  }
>>> >
>>> >  /** get mmap offset */
>>> > --
>>> > 1.9.1
>>> >
>>>
>>> Any comment for this patch ?
>>
>> Sorry for the delay, I wanted to get a chance to test it. It seems to pass the
>> usual regression tests. LGTM.
>>
>
> Jordan, This patch is not merged in 4.18-rc-1.

this was on my list to pull into msm-next for 4.19 as soon as I have a
chance to do my next round of pulling patches from patchwork, so it
should show up in linux-next shortly..

BR,
-R
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