[Intel-gfx] [PATCH 3/7] drm/i915: Allow page pinning to be in the background

[Matthew Auld]

On Mon, 3 Jun 2019 at 18:49, Chris Wilson <chris at chris-wilson.co.uk> wrote:
>
> Assume that pages may be pinned in a background task and use a
> completion event to synchronise with callers that must access the pages
> immediately.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/gem/i915_gem_object.c    |  1 +
>  drivers/gpu/drm/i915/gem/i915_gem_object.h    |  7 +--
>  .../gpu/drm/i915/gem/i915_gem_object_types.h  |  3 ++
>  drivers/gpu/drm/i915/gem/i915_gem_pages.c     | 53 +++++++++++++++----
>  4 files changed, 52 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
> index 2702e060102e..2c5a02274170 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
> @@ -79,6 +79,7 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
>         obj->mm.madv = I915_MADV_WILLNEED;
>         INIT_RADIX_TREE(&obj->mm.get_page.radix, GFP_KERNEL | __GFP_NOWARN);
>         mutex_init(&obj->mm.get_page.lock);
> +       init_completion(&obj->mm.completion);
>  }
>
>  /**
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
> index 7cb1871d7128..194e4fb6a259 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
> @@ -240,7 +240,7 @@ int ____i915_gem_object_get_pages(struct drm_i915_gem_object *obj);
>  int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj);
>
>  static inline int __must_check
> -i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
> +i915_gem_object_pin_pages_async(struct drm_i915_gem_object *obj)
>  {
>         might_lock(&obj->mm.lock);
>
> @@ -250,6 +250,9 @@ i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
>         return __i915_gem_object_get_pages(obj);
>  }
>
> +int __must_check
> +i915_gem_object_pin_pages(struct drm_i915_gem_object *obj);
> +
>  static inline bool
>  i915_gem_object_has_pages(struct drm_i915_gem_object *obj)
>  {
> @@ -273,9 +276,7 @@ i915_gem_object_has_pinned_pages(struct drm_i915_gem_object *obj)
>  static inline void
>  __i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj)
>  {
> -       GEM_BUG_ON(!i915_gem_object_has_pages(obj));
>         GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
> -
>         atomic_dec(&obj->mm.pages_pin_count);
>  }
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> index 41d2e7c8e332..615a59b927d6 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> @@ -7,6 +7,7 @@
>  #ifndef __I915_GEM_OBJECT_TYPES_H__
>  #define __I915_GEM_OBJECT_TYPES_H__
>
> +#include <linux/completion.h>
>  #include <linux/reservation.h>
>
>  #include <drm/drm_gem.h>
> @@ -211,6 +212,8 @@ struct drm_i915_gem_object {
>                  */
>                 struct list_head link;
>
> +               struct completion completion;
> +
>                 /**
>                  * Advice: are the backing pages purgeable?
>                  */
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
> index 7868dd48d931..68262231f56f 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
> @@ -72,21 +72,18 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
>
>                 spin_unlock(&i915->mm.obj_lock);
>         }
> +
> +       complete_all(&obj->mm.completion);
>  }

Worth having  __i915_gem_object_set_pages_error(struct
drm_i915_gem_object, int err) at some point?

Reviewed-by: Matthew Auld <matthew.auld at intel.com>