diff mbox

[11/24] drm: Introduce an iterator over holes in the drm_mm range manager

Message ID 1346340679-7699-12-git-send-email-chris@chris-wilson.co.uk (mailing list archive)
State Superseded
Headers show

Commit Message

Chris Wilson Aug. 30, 2012, 3:31 p.m. UTC
This will be used i915 in forthcoming patches in order to measure the
largest contiguous chunk of memory available for enabling chipset
features.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Airlie <airlied@redhat.com>
---
 drivers/gpu/drm/drm_mm.c |   55 +++++++++++++++-------------------------------
 include/drm/drm_mm.h     |   26 ++++++++++++++++++++++
 2 files changed, 44 insertions(+), 37 deletions(-)

Comments

Daniel Vetter Oct. 25, 2012, 7:22 p.m. UTC | #1
On Thu, Aug 30, 2012 at 04:31:06PM +0100, Chris Wilson wrote:
> This will be used i915 in forthcoming patches in order to measure the
> largest contiguous chunk of memory available for enabling chipset
> features.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Dave Airlie <airlied@redhat.com>

While discussing the iterator in private a bit with Ben I've noticed that
you've ignore my bikeshed! tsk ... ;-)

http://lists.freedesktop.org/archives/intel-gfx/2012-September/020436.html

-Daniel

> ---
>  drivers/gpu/drm/drm_mm.c |   55 +++++++++++++++-------------------------------
>  include/drm/drm_mm.h     |   26 ++++++++++++++++++++++
>  2 files changed, 44 insertions(+), 37 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> index 5db8c20..c3d11ec 100644
> --- a/drivers/gpu/drm/drm_mm.c
> +++ b/drivers/gpu/drm/drm_mm.c
> @@ -102,20 +102,6 @@ int drm_mm_pre_get(struct drm_mm *mm)
>  }
>  EXPORT_SYMBOL(drm_mm_pre_get);
>  
> -static inline unsigned long drm_mm_hole_node_start(struct drm_mm_node *hole_node)
> -{
> -	return hole_node->start + hole_node->size;
> -}
> -
> -static inline unsigned long drm_mm_hole_node_end(struct drm_mm_node *hole_node)
> -{
> -	struct drm_mm_node *next_node =
> -		list_entry(hole_node->node_list.next, struct drm_mm_node,
> -			   node_list);
> -
> -	return next_node->start;
> -}
> -
>  static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
>  				 struct drm_mm_node *node,
>  				 unsigned long size, unsigned alignment,
> @@ -127,7 +113,7 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
>  	unsigned long adj_start = hole_start;
>  	unsigned long adj_end = hole_end;
>  
> -	BUG_ON(!hole_node->hole_follows || node->allocated);
> +	BUG_ON(node->allocated);
>  
>  	if (mm->color_adjust)
>  		mm->color_adjust(hole_node, color, &adj_start, &adj_end);
> @@ -168,15 +154,10 @@ struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
>  {
>  	struct drm_mm_node *hole, *node;
>  	unsigned long end = start + size;
> +	unsigned long hole_start;
> +	unsigned long hole_end;
>  
> -	list_for_each_entry(hole, &mm->hole_stack, hole_stack) {
> -		unsigned long hole_start;
> -		unsigned long hole_end;
> -
> -		BUG_ON(!hole->hole_follows);
> -		hole_start = drm_mm_hole_node_start(hole);
> -		hole_end = drm_mm_hole_node_end(hole);
> -
> +	drm_mm_for_each_hole(hole, mm, hole_start, hole_end) {
>  		if (hole_start > start || hole_end < end)
>  			continue;
>  
> @@ -361,8 +342,10 @@ void drm_mm_remove_node(struct drm_mm_node *node)
>  				== drm_mm_hole_node_end(node));
>  		list_del(&node->hole_stack);
>  	} else
> -		BUG_ON(drm_mm_hole_node_start(node)
> -				!= drm_mm_hole_node_end(node));
> +		BUG_ON(node->start + node->size !=
> +		       list_entry(node->node_list.next,
> +				  struct drm_mm_node, node_list)->start);
> +
>  
>  	if (!prev_node->hole_follows) {
>  		prev_node->hole_follows = 1;
> @@ -420,6 +403,8 @@ struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
>  {
>  	struct drm_mm_node *entry;
>  	struct drm_mm_node *best;
> +	unsigned long adj_start;
> +	unsigned long adj_end;
>  	unsigned long best_size;
>  
>  	BUG_ON(mm->scanned_blocks);
> @@ -427,17 +412,13 @@ struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
>  	best = NULL;
>  	best_size = ~0UL;
>  
> -	list_for_each_entry(entry, &mm->hole_stack, hole_stack) {
> -		unsigned long adj_start = drm_mm_hole_node_start(entry);
> -		unsigned long adj_end = drm_mm_hole_node_end(entry);
> -
> +	drm_mm_for_each_hole(entry, mm, adj_start, adj_end) {
>  		if (mm->color_adjust) {
>  			mm->color_adjust(entry, color, &adj_start, &adj_end);
>  			if (adj_end <= adj_start)
>  				continue;
>  		}
>  
> -		BUG_ON(!entry->hole_follows);
>  		if (!check_free_hole(adj_start, adj_end, size, alignment))
>  			continue;
>  
> @@ -464,6 +445,8 @@ struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
>  {
>  	struct drm_mm_node *entry;
>  	struct drm_mm_node *best;
> +	unsigned long adj_start;
> +	unsigned long adj_end;
>  	unsigned long best_size;
>  
>  	BUG_ON(mm->scanned_blocks);
> @@ -471,13 +454,11 @@ struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
>  	best = NULL;
>  	best_size = ~0UL;
>  
> -	list_for_each_entry(entry, &mm->hole_stack, hole_stack) {
> -		unsigned long adj_start = drm_mm_hole_node_start(entry) < start ?
> -			start : drm_mm_hole_node_start(entry);
> -		unsigned long adj_end = drm_mm_hole_node_end(entry) > end ?
> -			end : drm_mm_hole_node_end(entry);
> -
> -		BUG_ON(!entry->hole_follows);
> +	drm_mm_for_each_hole(entry, mm, adj_start, adj_end) {
> +		if (adj_start < start)
> +			adj_start = start;
> +		if (adj_end > end)
> +			adj_end = end;
>  
>  		if (mm->color_adjust) {
>  			mm->color_adjust(entry, color, &adj_start, &adj_end);
> diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
> index 4020f96..d710a10 100644
> --- a/include/drm/drm_mm.h
> +++ b/include/drm/drm_mm.h
> @@ -89,6 +89,19 @@ static inline bool drm_mm_initialized(struct drm_mm *mm)
>  {
>  	return mm->hole_stack.next;
>  }
> +
> +static inline unsigned long drm_mm_hole_node_start(struct drm_mm_node *hole_node)
> +{
> +	BUG_ON(!hole_node->hole_follows);
> +	return hole_node->start + hole_node->size;
> +}
> +
> +static inline unsigned long drm_mm_hole_node_end(struct drm_mm_node *hole_node)
> +{
> +	return list_entry(hole_node->node_list.next,
> +			  struct drm_mm_node, node_list)->start;
> +}
> +
>  #define drm_mm_for_each_node(entry, mm) list_for_each_entry(entry, \
>  						&(mm)->head_node.node_list, \
>  						node_list)
> @@ -99,6 +112,19 @@ static inline bool drm_mm_initialized(struct drm_mm *mm)
>  	     entry != NULL; entry = next, \
>  		next = entry ? list_entry(entry->node_list.next, \
>  			struct drm_mm_node, node_list) : NULL) \
> +
> +/* Note that we need to unroll list_for_each_entry in order to inline
> + * setting hole_start and hole_end on each iteration and keep the
> + * macro sane.
> + */
> +#define drm_mm_for_each_hole(entry, mm, hole_start, hole_end) \
> +	for (entry = list_entry((mm)->hole_stack.next, typeof(struct drm_mm_node), hole_stack); \
> +	     &entry->hole_stack != &(mm)->hole_stack ? \
> +	     hole_start = drm_mm_hole_node_start(entry), \
> +	     hole_end = drm_mm_hole_node_end(entry) : \
> +	     0; \
> +	     entry = list_entry(entry->hole_stack.next, typeof(struct drm_mm_node), hole_stack))
> +
>  /*
>   * Basic range manager support (drm_mm.c)
>   */
> -- 
> 1.7.10.4
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
Ben Widawsky Oct. 25, 2012, 8:54 p.m. UTC | #2
On Thu, 25 Oct 2012 21:22:25 +0200
Daniel Vetter <daniel@ffwll.ch> wrote:

> On Thu, Aug 30, 2012 at 04:31:06PM +0100, Chris Wilson wrote:
> > This will be used i915 in forthcoming patches in order to measure the
> > largest contiguous chunk of memory available for enabling chipset
> > features.
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Dave Airlie <airlied@redhat.com>
> 
> While discussing the iterator in private a bit with Ben I've noticed that
> you've ignore my bikeshed! tsk ... ;-)
> 
> http://lists.freedesktop.org/archives/intel-gfx/2012-September/020436.html
> 
> -Daniel

While the macro is undeniably horendous to read, I think Daniel's
suggestion makes it slightly better simply for reading.

> 
> > ---
> >  drivers/gpu/drm/drm_mm.c |   55 +++++++++++++++-------------------------------
> >  include/drm/drm_mm.h     |   26 ++++++++++++++++++++++
> >  2 files changed, 44 insertions(+), 37 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> > index 5db8c20..c3d11ec 100644
> > --- a/drivers/gpu/drm/drm_mm.c
> > +++ b/drivers/gpu/drm/drm_mm.c
> > @@ -102,20 +102,6 @@ int drm_mm_pre_get(struct drm_mm *mm)
> >  }
> >  EXPORT_SYMBOL(drm_mm_pre_get);
> >  
> > -static inline unsigned long drm_mm_hole_node_start(struct drm_mm_node *hole_node)
> > -{
> > -	return hole_node->start + hole_node->size;
> > -}
> > -
> > -static inline unsigned long drm_mm_hole_node_end(struct drm_mm_node *hole_node)
> > -{
> > -	struct drm_mm_node *next_node =
> > -		list_entry(hole_node->node_list.next, struct drm_mm_node,
> > -			   node_list);
> > -
> > -	return next_node->start;
> > -}
> > -
> >  static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
> >  				 struct drm_mm_node *node,
> >  				 unsigned long size, unsigned alignment,
> > @@ -127,7 +113,7 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
> >  	unsigned long adj_start = hole_start;
> >  	unsigned long adj_end = hole_end;
> >  
> > -	BUG_ON(!hole_node->hole_follows || node->allocated);
> > +	BUG_ON(node->allocated);
> >  
> >  	if (mm->color_adjust)
> >  		mm->color_adjust(hole_node, color, &adj_start, &adj_end);
> > @@ -168,15 +154,10 @@ struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
> >  {
> >  	struct drm_mm_node *hole, *node;
> >  	unsigned long end = start + size;
> > +	unsigned long hole_start;
> > +	unsigned long hole_end;
> >  
> > -	list_for_each_entry(hole, &mm->hole_stack, hole_stack) {
> > -		unsigned long hole_start;
> > -		unsigned long hole_end;
> > -
> > -		BUG_ON(!hole->hole_follows);
> > -		hole_start = drm_mm_hole_node_start(hole);
> > -		hole_end = drm_mm_hole_node_end(hole);
> > -
> > +	drm_mm_for_each_hole(hole, mm, hole_start, hole_end) {
> >  		if (hole_start > start || hole_end < end)
> >  			continue;
> >  
> > @@ -361,8 +342,10 @@ void drm_mm_remove_node(struct drm_mm_node *node)
> >  				== drm_mm_hole_node_end(node));
> >  		list_del(&node->hole_stack);
> >  	} else
> > -		BUG_ON(drm_mm_hole_node_start(node)
> > -				!= drm_mm_hole_node_end(node));
> > +		BUG_ON(node->start + node->size !=
> > +		       list_entry(node->node_list.next,
> > +				  struct drm_mm_node, node_list)->start);
> > +
> >  
> >  	if (!prev_node->hole_follows) {
> >  		prev_node->hole_follows = 1;
> > @@ -420,6 +403,8 @@ struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
> >  {
> >  	struct drm_mm_node *entry;
> >  	struct drm_mm_node *best;
> > +	unsigned long adj_start;
> > +	unsigned long adj_end;
> >  	unsigned long best_size;
> >  
> >  	BUG_ON(mm->scanned_blocks);
> > @@ -427,17 +412,13 @@ struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
> >  	best = NULL;
> >  	best_size = ~0UL;
> >  
> > -	list_for_each_entry(entry, &mm->hole_stack, hole_stack) {
> > -		unsigned long adj_start = drm_mm_hole_node_start(entry);
> > -		unsigned long adj_end = drm_mm_hole_node_end(entry);
> > -
> > +	drm_mm_for_each_hole(entry, mm, adj_start, adj_end) {
> >  		if (mm->color_adjust) {
> >  			mm->color_adjust(entry, color, &adj_start, &adj_end);
> >  			if (adj_end <= adj_start)
> >  				continue;
> >  		}
> >  
> > -		BUG_ON(!entry->hole_follows);
> >  		if (!check_free_hole(adj_start, adj_end, size, alignment))
> >  			continue;
> >  
> > @@ -464,6 +445,8 @@ struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
> >  {
> >  	struct drm_mm_node *entry;
> >  	struct drm_mm_node *best;
> > +	unsigned long adj_start;
> > +	unsigned long adj_end;
> >  	unsigned long best_size;
> >  
> >  	BUG_ON(mm->scanned_blocks);
> > @@ -471,13 +454,11 @@ struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
> >  	best = NULL;
> >  	best_size = ~0UL;
> >  
> > -	list_for_each_entry(entry, &mm->hole_stack, hole_stack) {
> > -		unsigned long adj_start = drm_mm_hole_node_start(entry) < start ?
> > -			start : drm_mm_hole_node_start(entry);
> > -		unsigned long adj_end = drm_mm_hole_node_end(entry) > end ?
> > -			end : drm_mm_hole_node_end(entry);
> > -
> > -		BUG_ON(!entry->hole_follows);
> > +	drm_mm_for_each_hole(entry, mm, adj_start, adj_end) {
> > +		if (adj_start < start)
> > +			adj_start = start;
> > +		if (adj_end > end)
> > +			adj_end = end;
> >  
> >  		if (mm->color_adjust) {
> >  			mm->color_adjust(entry, color, &adj_start, &adj_end);
> > diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
> > index 4020f96..d710a10 100644
> > --- a/include/drm/drm_mm.h
> > +++ b/include/drm/drm_mm.h
> > @@ -89,6 +89,19 @@ static inline bool drm_mm_initialized(struct drm_mm *mm)
> >  {
> >  	return mm->hole_stack.next;
> >  }
> > +
> > +static inline unsigned long drm_mm_hole_node_start(struct drm_mm_node *hole_node)
> > +{
> > +	BUG_ON(!hole_node->hole_follows);
> > +	return hole_node->start + hole_node->size;
> > +}
> > +
> > +static inline unsigned long drm_mm_hole_node_end(struct drm_mm_node *hole_node)
> > +{
> > +	return list_entry(hole_node->node_list.next,
> > +			  struct drm_mm_node, node_list)->start;
> > +}
> > +
> >  #define drm_mm_for_each_node(entry, mm) list_for_each_entry(entry, \
> >  						&(mm)->head_node.node_list, \
> >  						node_list)
> > @@ -99,6 +112,19 @@ static inline bool drm_mm_initialized(struct drm_mm *mm)
> >  	     entry != NULL; entry = next, \
> >  		next = entry ? list_entry(entry->node_list.next, \
> >  			struct drm_mm_node, node_list) : NULL) \
> > +
> > +/* Note that we need to unroll list_for_each_entry in order to inline
> > + * setting hole_start and hole_end on each iteration and keep the
> > + * macro sane.
> > + */
> > +#define drm_mm_for_each_hole(entry, mm, hole_start, hole_end) \
> > +	for (entry = list_entry((mm)->hole_stack.next, typeof(struct drm_mm_node), hole_stack); \
> > +	     &entry->hole_stack != &(mm)->hole_stack ? \
> > +	     hole_start = drm_mm_hole_node_start(entry), \
> > +	     hole_end = drm_mm_hole_node_end(entry) : \
> > +	     0; \
> > +	     entry = list_entry(entry->hole_stack.next, typeof(struct drm_mm_node), hole_stack))
> > +
> >  /*
> >   * Basic range manager support (drm_mm.c)
> >   */
> > -- 
> > 1.7.10.4
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
Chris Wilson Oct. 26, 2012, 10:55 a.m. UTC | #3
On Thu, 25 Oct 2012 13:54:42 -0700, Ben Widawsky <ben@bwidawsk.net> wrote:
> On Thu, 25 Oct 2012 21:22:25 +0200
> Daniel Vetter <daniel@ffwll.ch> wrote:
> 
> > On Thu, Aug 30, 2012 at 04:31:06PM +0100, Chris Wilson wrote:
> > > This will be used i915 in forthcoming patches in order to measure the
> > > largest contiguous chunk of memory available for enabling chipset
> > > features.
> > > 
> > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > > Cc: Dave Airlie <airlied@redhat.com>
> > 
> > While discussing the iterator in private a bit with Ben I've noticed that
> > you've ignore my bikeshed! tsk ... ;-)
> > 
> > http://lists.freedesktop.org/archives/intel-gfx/2012-September/020436.html
> > 
> > -Daniel
> 
> While the macro is undeniably horendous to read, I think Daniel's
> suggestion makes it slightly better simply for reading.

That wasn't an intentional snub, macro changes applied.
Thanks,
-Chris
diff mbox

Patch

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index 5db8c20..c3d11ec 100644
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -102,20 +102,6 @@  int drm_mm_pre_get(struct drm_mm *mm)
 }
 EXPORT_SYMBOL(drm_mm_pre_get);
 
-static inline unsigned long drm_mm_hole_node_start(struct drm_mm_node *hole_node)
-{
-	return hole_node->start + hole_node->size;
-}
-
-static inline unsigned long drm_mm_hole_node_end(struct drm_mm_node *hole_node)
-{
-	struct drm_mm_node *next_node =
-		list_entry(hole_node->node_list.next, struct drm_mm_node,
-			   node_list);
-
-	return next_node->start;
-}
-
 static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
 				 struct drm_mm_node *node,
 				 unsigned long size, unsigned alignment,
@@ -127,7 +113,7 @@  static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
 	unsigned long adj_start = hole_start;
 	unsigned long adj_end = hole_end;
 
-	BUG_ON(!hole_node->hole_follows || node->allocated);
+	BUG_ON(node->allocated);
 
 	if (mm->color_adjust)
 		mm->color_adjust(hole_node, color, &adj_start, &adj_end);
@@ -168,15 +154,10 @@  struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
 {
 	struct drm_mm_node *hole, *node;
 	unsigned long end = start + size;
+	unsigned long hole_start;
+	unsigned long hole_end;
 
-	list_for_each_entry(hole, &mm->hole_stack, hole_stack) {
-		unsigned long hole_start;
-		unsigned long hole_end;
-
-		BUG_ON(!hole->hole_follows);
-		hole_start = drm_mm_hole_node_start(hole);
-		hole_end = drm_mm_hole_node_end(hole);
-
+	drm_mm_for_each_hole(hole, mm, hole_start, hole_end) {
 		if (hole_start > start || hole_end < end)
 			continue;
 
@@ -361,8 +342,10 @@  void drm_mm_remove_node(struct drm_mm_node *node)
 				== drm_mm_hole_node_end(node));
 		list_del(&node->hole_stack);
 	} else
-		BUG_ON(drm_mm_hole_node_start(node)
-				!= drm_mm_hole_node_end(node));
+		BUG_ON(node->start + node->size !=
+		       list_entry(node->node_list.next,
+				  struct drm_mm_node, node_list)->start);
+
 
 	if (!prev_node->hole_follows) {
 		prev_node->hole_follows = 1;
@@ -420,6 +403,8 @@  struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
 {
 	struct drm_mm_node *entry;
 	struct drm_mm_node *best;
+	unsigned long adj_start;
+	unsigned long adj_end;
 	unsigned long best_size;
 
 	BUG_ON(mm->scanned_blocks);
@@ -427,17 +412,13 @@  struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
 	best = NULL;
 	best_size = ~0UL;
 
-	list_for_each_entry(entry, &mm->hole_stack, hole_stack) {
-		unsigned long adj_start = drm_mm_hole_node_start(entry);
-		unsigned long adj_end = drm_mm_hole_node_end(entry);
-
+	drm_mm_for_each_hole(entry, mm, adj_start, adj_end) {
 		if (mm->color_adjust) {
 			mm->color_adjust(entry, color, &adj_start, &adj_end);
 			if (adj_end <= adj_start)
 				continue;
 		}
 
-		BUG_ON(!entry->hole_follows);
 		if (!check_free_hole(adj_start, adj_end, size, alignment))
 			continue;
 
@@ -464,6 +445,8 @@  struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
 {
 	struct drm_mm_node *entry;
 	struct drm_mm_node *best;
+	unsigned long adj_start;
+	unsigned long adj_end;
 	unsigned long best_size;
 
 	BUG_ON(mm->scanned_blocks);
@@ -471,13 +454,11 @@  struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
 	best = NULL;
 	best_size = ~0UL;
 
-	list_for_each_entry(entry, &mm->hole_stack, hole_stack) {
-		unsigned long adj_start = drm_mm_hole_node_start(entry) < start ?
-			start : drm_mm_hole_node_start(entry);
-		unsigned long adj_end = drm_mm_hole_node_end(entry) > end ?
-			end : drm_mm_hole_node_end(entry);
-
-		BUG_ON(!entry->hole_follows);
+	drm_mm_for_each_hole(entry, mm, adj_start, adj_end) {
+		if (adj_start < start)
+			adj_start = start;
+		if (adj_end > end)
+			adj_end = end;
 
 		if (mm->color_adjust) {
 			mm->color_adjust(entry, color, &adj_start, &adj_end);
diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
index 4020f96..d710a10 100644
--- a/include/drm/drm_mm.h
+++ b/include/drm/drm_mm.h
@@ -89,6 +89,19 @@  static inline bool drm_mm_initialized(struct drm_mm *mm)
 {
 	return mm->hole_stack.next;
 }
+
+static inline unsigned long drm_mm_hole_node_start(struct drm_mm_node *hole_node)
+{
+	BUG_ON(!hole_node->hole_follows);
+	return hole_node->start + hole_node->size;
+}
+
+static inline unsigned long drm_mm_hole_node_end(struct drm_mm_node *hole_node)
+{
+	return list_entry(hole_node->node_list.next,
+			  struct drm_mm_node, node_list)->start;
+}
+
 #define drm_mm_for_each_node(entry, mm) list_for_each_entry(entry, \
 						&(mm)->head_node.node_list, \
 						node_list)
@@ -99,6 +112,19 @@  static inline bool drm_mm_initialized(struct drm_mm *mm)
 	     entry != NULL; entry = next, \
 		next = entry ? list_entry(entry->node_list.next, \
 			struct drm_mm_node, node_list) : NULL) \
+
+/* Note that we need to unroll list_for_each_entry in order to inline
+ * setting hole_start and hole_end on each iteration and keep the
+ * macro sane.
+ */
+#define drm_mm_for_each_hole(entry, mm, hole_start, hole_end) \
+	for (entry = list_entry((mm)->hole_stack.next, typeof(struct drm_mm_node), hole_stack); \
+	     &entry->hole_stack != &(mm)->hole_stack ? \
+	     hole_start = drm_mm_hole_node_start(entry), \
+	     hole_end = drm_mm_hole_node_end(entry) : \
+	     0; \
+	     entry = list_entry(entry->hole_stack.next, typeof(struct drm_mm_node), hole_stack))
+
 /*
  * Basic range manager support (drm_mm.c)
  */