On 17-Apr-2018 9:45 PM, "Matthew Wilcox" <willy@infradead.org> wrote:
>
> On Tue, Apr 17, 2018 at 09:14:32PM +0530, Souptick Joarder wrote:
> > Not exactly. The plan for these patches is to introduce new vm_fault_t
type
> > in vm_operations_struct fault handlers. It's now available in 4.17-rc1.
We will
> > push all the required drivers/filesystem changes through different
maintainers
> > to linus tree. Once everything is converted into vm_fault_t type then
Changing
> > it from a signed to an unsigned int causes GCC to warn about an
assignment
> > from an incompatible type -- int foo(void) is incompatible with
> > unsigned int foo(void).
> >
> > Please refer 1c8f422059ae ("mm: change return type to vm_fault_t") in
4.17-rc1.
>
> I think this patch would be clearer if you did
>
> -       int ret;
> +       int err;
> +       vm_fault_t ret;
>
> Then it would be clearer to the maintainer that you're splitting apart the
> VM_FAULT and errno codes.
>
> Sorry for not catching this during initial review.

Ok, I will make required changes and send v2. Sorry, even I missed this :)
>
> > On Tue, Apr 17, 2018 at 8:59 PM, Jani Nikula
> > <jani.nikula@linux.intel.com> wrote:
> > > On Tue, 17 Apr 2018, 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.
> > >>
> > >> Reference id -> 1c8f422059ae ("mm: change return type to
> > >> vm_fault_t")
> > >>
> > >> Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> > >> ---
> > >>  drivers/gpu/drm/i915/i915_drv.h |  3 ++-
> > >>  drivers/gpu/drm/i915/i915_gem.c | 15 ++++++++-------
> > >>  2 files changed, 10 insertions(+), 8 deletions(-)
> > >>
> > >> diff --git a/drivers/gpu/drm/i915/i915_drv.h
b/drivers/gpu/drm/i915/i915_drv.h
> > >> index a42deeb..95b0d50 100644
> > >> --- a/drivers/gpu/drm/i915/i915_drv.h
> > >> +++ b/drivers/gpu/drm/i915/i915_drv.h
> > >> @@ -51,6 +51,7 @@
> > >>  #include <drm/drm_gem.h>
> > >>  #include <drm/drm_auth.h>
> > >>  #include <drm/drm_cache.h>
> > >> +#include <linux/mm_types.h>
> > >>
> > >>  #include "i915_params.h"
> > >>  #include "i915_reg.h"
> > >> @@ -3363,7 +3364,7 @@ int i915_gem_wait_for_idle(struct
drm_i915_private *dev_priv,
> > >>                          unsigned int flags);
> > >>  int __must_check i915_gem_suspend(struct drm_i915_private
*dev_priv);
> > >>  void i915_gem_resume(struct drm_i915_private *dev_priv);
> > >> -int i915_gem_fault(struct vm_fault *vmf);
> > >> +vm_fault_t i915_gem_fault(struct vm_fault *vmf);
> > >>  int i915_gem_object_wait(struct drm_i915_gem_object *obj,
> > >>                        unsigned int flags,
> > >>                        long timeout,
> > >> diff --git a/drivers/gpu/drm/i915/i915_gem.c
b/drivers/gpu/drm/i915/i915_gem.c
> > >> index dd89abd..bdac690 100644
> > >> --- a/drivers/gpu/drm/i915/i915_gem.c
> > >> +++ b/drivers/gpu/drm/i915/i915_gem.c
> > >> @@ -1882,7 +1882,7 @@ int i915_gem_mmap_gtt_version(void)
> > >>   * The current feature set supported by i915_gem_fault() and thus
GTT mmaps
> > >>   * is exposed via I915_PARAM_MMAP_GTT_VERSION (see
i915_gem_mmap_gtt_version).
> > >>   */
> > >> -int i915_gem_fault(struct vm_fault *vmf)
> > >> +vm_fault_t i915_gem_fault(struct vm_fault *vmf)
> > >>  {
> > >>  #define MIN_CHUNK_PAGES ((1 << 20) >> PAGE_SHIFT) /* 1 MiB */
> > >>       struct vm_area_struct *area = vmf->vma;
> > >> @@ -1895,6 +1895,7 @@ int i915_gem_fault(struct vm_fault *vmf)
> > >>       pgoff_t page_offset;
> > >>       unsigned int flags;
> > >>       int ret;
> > >> +     vm_fault_t retval;
> > >
> > > What's the point of changing the name? An unnecessary change.
> > >
> > > BR,
> > > Jani.
> > >
> > >>
> > >>       /* We don't use vmf->pgoff since that has the fake offset */
> > >>       page_offset = (vmf->address - area->vm_start) >> PAGE_SHIFT;
> > >> @@ -2000,7 +2001,7 @@ int i915_gem_fault(struct vm_fault *vmf)
> > >>                * and so needs to be reported.
> > >>                */
> > >>               if (!i915_terminally_wedged(&dev_priv->gpu_error)) {
> > >> -                     ret = VM_FAULT_SIGBUS;
> > >> +                     retval = VM_FAULT_SIGBUS;
> > >>                       break;
> > >>               }
> > >>       case -EAGAIN:
> > >> @@ -2017,21 +2018,21 @@ int i915_gem_fault(struct vm_fault *vmf)
> > >>                * EBUSY is ok: this just means that another thread
> > >>                * already did the job.
> > >>                */
> > >> -             ret = VM_FAULT_NOPAGE;
> > >> +             retval = VM_FAULT_NOPAGE;
> > >>               break;
> > >>       case -ENOMEM:
> > >> -             ret = VM_FAULT_OOM;
> > >> +             retval = VM_FAULT_OOM;
> > >>               break;
> > >>       case -ENOSPC:
> > >>       case -EFAULT:
> > >> -             ret = VM_FAULT_SIGBUS;
> > >> +             retval = VM_FAULT_SIGBUS;
> > >>               break;
> > >>       default:
> > >>               WARN_ONCE(ret, "unhandled error in i915_gem_fault:
%i\n", ret);
> > >> -             ret = VM_FAULT_SIGBUS;
> > >> +             retval = VM_FAULT_SIGBUS;
> > >>               break;
> > >>       }
> > >> -     return ret;
> > >> +     return retval;
> > >>  }
> > >>
> > >>  static void __i915_gem_object_release_mmap(struct
drm_i915_gem_object *obj)
> > >> --
> > >> 1.9.1
> > >>
> > >
> > > --
> > > Jani Nikula, Intel Open Source Technology Center