On Fri, 29 Jan 2016, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
> commit 033908aed5a596f6202c848c6bbc8a40fb1a8490
> Author: Dave Gordon <david.s.gordon@xxxxxxxxx>
> Date: Thu Dec 10 18:51:23 2015 +0000
>
> drm/i915: mark GEM object pages dirty when mapped & written by the CPU
>
> introduced a check into i915_gem_object_get_dirty_pages() that returned
> a NULL pointer when called with a bad object, one that was not backed by
> shmemfs. This WARN was too strict as we can work on all struct page
> backed objects, and resulted in a WARN + GPF for existing userspace. In
> order to differentiate the various types of objects, add a new flags field
> to the i915_gem_object_ops struct to describe their capabilities, with
> the first flag being whether the object has struct pages.
>
> v2: Drop silly const before an integer in the structure declaration.
>
> Testcase: igt/gem_userptr_blits/relocations
> Reported-and-tested-by: Kristian Høgsberg Kristensen <krh@xxxxxxxxxxxxx>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Dave Gordon <david.s.gordon@xxxxxxxxx>
> Cc: Kristian Høgsberg Kristensen <krh@xxxxxxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Reviewed-by: Dave Gordon <david.s.gordon@xxxxxxxxx>
> Reviewed-by: Kristian Høgsberg Kristensen <krh@xxxxxxxxxxxxx>
Cc: drm-intel-fixes@xxxxxxxxxxxxxxxxxxxxx
to pick for 4.5
> ---
> drivers/gpu/drm/i915/i915_drv.h | 4 ++++
> drivers/gpu/drm/i915/i915_gem.c | 3 ++-
> drivers/gpu/drm/i915/i915_gem_userptr.c | 3 ++-
> 3 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 905e90f25957..a2d2f08b7515 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2000,6 +2000,9 @@ enum hdmi_force_audio {
> #define I915_GTT_OFFSET_NONE ((u32)-1)
>
> struct drm_i915_gem_object_ops {
> + unsigned int flags;
> +#define I915_GEM_OBJECT_HAS_STRUCT_PAGE 0x1
> +
> /* Interface between the GEM object and its backing storage.
> * get_pages() is called once prior to the use of the associated set
> * of pages before to binding them into the GTT, and put_pages() is
> @@ -2015,6 +2018,7 @@ struct drm_i915_gem_object_ops {
> */
> int (*get_pages)(struct drm_i915_gem_object *);
> void (*put_pages)(struct drm_i915_gem_object *);
> +
> int (*dmabuf_export)(struct drm_i915_gem_object *);
> void (*release)(struct drm_i915_gem_object *);
> };
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index a928823507c5..e9b19bca1383 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -4465,6 +4465,7 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
> }
>
> static const struct drm_i915_gem_object_ops i915_gem_object_ops = {
> + .flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE,
> .get_pages = i915_gem_object_get_pages_gtt,
> .put_pages = i915_gem_object_put_pages_gtt,
> };
> @@ -5309,7 +5310,7 @@ i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj, int n)
> struct page *page;
>
> /* Only default objects have per-page dirty tracking */
> - if (WARN_ON(obj->ops != &i915_gem_object_ops))
> + if (WARN_ON((obj->ops->flags & I915_GEM_OBJECT_HAS_STRUCT_PAGE) == 0))
> return NULL;
>
> page = i915_gem_object_get_page(obj, n);
> diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
> index 74a4d1714879..7107f2fd38f5 100644
> --- a/drivers/gpu/drm/i915/i915_gem_userptr.c
> +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
> @@ -708,9 +708,10 @@ i915_gem_userptr_dmabuf_export(struct drm_i915_gem_object *obj)
> }
>
> static const struct drm_i915_gem_object_ops i915_gem_userptr_ops = {
> - .dmabuf_export = i915_gem_userptr_dmabuf_export,
> + .flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE,
> .get_pages = i915_gem_userptr_get_pages,
> .put_pages = i915_gem_userptr_put_pages,
> + .dmabuf_export = i915_gem_userptr_dmabuf_export,
> .release = i915_gem_userptr_release,
> };
--
Jani Nikula, Intel Open Source Technology Center
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