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
>
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