[PATCH 1/6] drm: pre allocate node for create_block

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi

On Wed, Jul 3, 2013 at 11:45 PM, Ben Widawsky <ben at bwidawsk.net> wrote:
> For an upcoming patch where we introduce the i915 VMA, it's ideal to
> have the drm_mm_node as part of the VMA struct (ie. it's pre-allocated).
> Part of the conversion to VMAs is to kill off obj->gtt_space. Doing this
> will break a bunch of code, but amongst them are 2 callers of
> drm_mm_create_block(), both related to stolen memory.
>
> It also allows us to embed the drm_mm_node into the object currently
> which provides a nice transition over to the new code.
>
> v2: Reordered to do before ripping out obj->gtt_offset.
> Some minor cleanups made available because of reordering.
>
> CC: <dri-devel at lists.freedesktop.org>
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> ---
>  drivers/gpu/drm/drm_mm.c               | 16 +++++----------
>  drivers/gpu/drm/i915/i915_gem_gtt.c    | 18 +++++++++++++----
>  drivers/gpu/drm/i915/i915_gem_stolen.c | 36 +++++++++++++++++++++++-----------
>  include/drm/drm_mm.h                   |  9 +++++----
>  4 files changed, 49 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> index 07cf99c..9e8dfbc 100644
> --- a/drivers/gpu/drm/drm_mm.c
> +++ b/drivers/gpu/drm/drm_mm.c
> @@ -147,12 +147,10 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
>         }
>  }
>
> -struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
> -                                       unsigned long start,
> -                                       unsigned long size,
> -                                       bool atomic)
> +int drm_mm_create_block(struct drm_mm *mm, struct drm_mm_node *node,
> +                       unsigned long start, unsigned long size)
>  {
> -       struct drm_mm_node *hole, *node;
> +       struct drm_mm_node *hole;
>         unsigned long end = start + size;
>         unsigned long hole_start;
>         unsigned long hole_end;
> @@ -161,10 +159,6 @@ struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
>                 if (hole_start > start || hole_end < end)
>                         continue;
>
> -               node = drm_mm_kmalloc(mm, atomic);
> -               if (unlikely(node == NULL))
> -                       return NULL;
> -
>                 node->start = start;
>                 node->size = size;
>                 node->mm = mm;
> @@ -184,11 +178,11 @@ struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
>                         node->hole_follows = 1;
>                 }
>
> -               return node;
> +               return 0;
>         }
>
>         WARN(1, "no hole found for block 0x%lx + 0x%lx\n", start, size);
> -       return NULL;
> +       return -ENOSPC;
>  }
>  EXPORT_SYMBOL(drm_mm_create_block);
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 66929ea..5c6fc0e 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -629,14 +629,24 @@ void i915_gem_setup_global_gtt(struct drm_device *dev,
>
>         /* Mark any preallocated objects as occupied */
>         list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list) {
> +               int ret;
>                 DRM_DEBUG_KMS("reserving preallocated space: %x + %zx\n",
>                               obj->gtt_offset, obj->base.size);
>
>                 BUG_ON(obj->gtt_space != I915_GTT_RESERVED);
> -               obj->gtt_space = drm_mm_create_block(&dev_priv->mm.gtt_space,
> -                                                    obj->gtt_offset,
> -                                                    obj->base.size,
> -                                                    false);
> +               obj->gtt_space = kzalloc(sizeof(*obj->gtt_space), GFP_KERNEL);
> +               if (!obj->gtt_space) {
> +                       DRM_ERROR("Failed to preserve all objects\n");
> +                       break;
> +               }
> +               ret = drm_mm_create_block(&dev_priv->mm.gtt_space,
> +                                         obj->gtt_space,
> +                                         obj->gtt_offset,
> +                                         obj->base.size);
> +               if (ret) {
> +                       DRM_DEBUG_KMS("Reservation failed\n");
> +                       kfree(obj->gtt_space);

Are you sure you don't need:
  obj->gtt_space = NULL;
here?
I am no expert in i915 gem handling, but looking at i915_gem.c I think
you might run into bugs if not.

Also, why did you add the "break;" above, but not here? I am confused.

> +               }
>                 obj->has_global_gtt_mapping = 1;
>         }
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
> index 8e02344..f9db84a 100644
> --- a/drivers/gpu/drm/i915/i915_gem_stolen.c
> +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
> @@ -330,6 +330,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
>         struct drm_i915_private *dev_priv = dev->dev_private;
>         struct drm_i915_gem_object *obj;
>         struct drm_mm_node *stolen;
> +       int ret;
>
>         if (dev_priv->mm.stolen_base == 0)
>                 return NULL;
> @@ -344,11 +345,15 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
>         if (WARN_ON(size == 0))
>                 return NULL;
>
> -       stolen = drm_mm_create_block(&dev_priv->mm.stolen,
> -                                    stolen_offset, size,
> -                                    false);
> -       if (stolen == NULL) {
> +       stolen = kzalloc(sizeof(*stolen), GFP_KERNEL);
> +       if (!stolen)
> +               return NULL;
> +
> +       ret = drm_mm_create_block(&dev_priv->mm.stolen, stolen, stolen_offset,
> +                                 size);
> +       if (ret) {
>                 DRM_DEBUG_KMS("failed to allocate stolen space\n");
> +               kfree(stolen);
>                 return NULL;
>         }
>
> @@ -369,13 +374,18 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
>          * later.
>          */
>         if (drm_mm_initialized(&dev_priv->mm.gtt_space)) {
> -               obj->gtt_space = drm_mm_create_block(&dev_priv->mm.gtt_space,
> -                                                    gtt_offset, size,
> -                                                    false);
> -               if (obj->gtt_space == NULL) {
> +               obj->gtt_space = kzalloc(sizeof(*obj->gtt_space), GFP_KERNEL);
> +               if (!obj->gtt_space) {
> +                       DRM_DEBUG_KMS("-ENOMEM stolen GTT space\n");
> +                       goto unref_out;
> +               }
> +
> +               ret = drm_mm_create_block(&dev_priv->mm.gtt_space,
> +                                         obj->gtt_space,
> +                                         gtt_offset, size);
> +               if (ret) {
>                         DRM_DEBUG_KMS("failed to allocate stolen GTT space\n");
> -                       drm_gem_object_unreference(&obj->base);
> -                       return NULL;
> +                       goto unref_out;

Again:
  kfree(obj->gtt_space);
  obj->gtt_space = NULL;
Otherwise, if gem-cleanup calls drm_mm_put_block() on an already
removed node, you end up with NULL-derefs in drm_mm.c

>                 }
>         } else
>                 obj->gtt_space = I915_GTT_RESERVED;
> @@ -385,8 +395,12 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
>
>         list_add_tail(&obj->global_list, &dev_priv->mm.bound_list);
>         list_add_tail(&obj->mm_list, &dev_priv->mm.inactive_list);
> -
>         return obj;
> +
> +unref_out:
> +       drm_gem_object_unreference(&obj->base);
> +       drm_mm_put_block(stolen);

"stolen" is already cleared by drm_gem_object_unreference(). So that's
a double-free here.

The drm_mm_create_block() change looks good.
Cheers
David

> +       return NULL;
>  }
>
>  void
> diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
> index 88591ef..d8b56b7 100644
> --- a/include/drm/drm_mm.h
> +++ b/include/drm/drm_mm.h
> @@ -138,10 +138,10 @@ static inline unsigned long drm_mm_hole_node_end(struct drm_mm_node *hole_node)
>  /*
>   * Basic range manager support (drm_mm.c)
>   */
> -extern struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
> -                                              unsigned long start,
> -                                              unsigned long size,
> -                                              bool atomic);
> +extern int drm_mm_create_block(struct drm_mm *mm,
> +                              struct drm_mm_node *node,
> +                              unsigned long start,
> +                              unsigned long size);
>  extern struct drm_mm_node *drm_mm_get_block_generic(struct drm_mm_node *node,
>                                                     unsigned long size,
>                                                     unsigned alignment,
> @@ -155,6 +155,7 @@ extern struct drm_mm_node *drm_mm_get_block_range_generic(
>                                                 unsigned long start,
>                                                 unsigned long end,
>                                                 int atomic);
> +
>  static inline struct drm_mm_node *drm_mm_get_block(struct drm_mm_node *parent,
>                                                    unsigned long size,
>                                                    unsigned alignment)
> --
> 1.8.3.2
>
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel


[Index of Archives]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]
  Powered by Linux