[PATCH 1/2] drm/mm: Add an iterator to optimally walk over holes for an allocation

[PATCH 1/2] drm/mm: Add an iterator to optimally walk over holes for an allocation

[Vivek Kasireddy]

This iterator relies on drm_mm_first_hole() and drm_mm_next_hole()
functions to identify suitable holes for an allocation of a given
size by efficently traversing the rbtree associated with the given
allocator.

It replaces the for loop in drm_mm_insert_node_in_range() and can
also be used by drm drivers to quickly identify holes of a certain
size within a given range.

Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
---
 drivers/gpu/drm/drm_mm.c | 28 ++++++++++++----------------
 include/drm/drm_mm.h     | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index 8257f9d4f619..416c849c10e5 100644
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -352,10 +352,10 @@ static struct drm_mm_node *find_hole_addr(struct drm_mm *mm, u64 addr, u64 size)
 	return node;
 }
 
-static struct drm_mm_node *
-first_hole(struct drm_mm *mm,
-	   u64 start, u64 end, u64 size,
-	   enum drm_mm_insert_mode mode)
+struct drm_mm_node *
+drm_mm_first_hole(struct drm_mm *mm,
+		  u64 start, u64 end, u64 size,
+		  enum drm_mm_insert_mode mode)
 {
 	switch (mode) {
 	default:
@@ -374,6 +374,7 @@ first_hole(struct drm_mm *mm,
 						hole_stack);
 	}
 }
+EXPORT_SYMBOL(drm_mm_first_hole);
 
 /**
  * DECLARE_NEXT_HOLE_ADDR - macro to declare next hole functions
@@ -410,11 +411,11 @@ static struct drm_mm_node *name(struct drm_mm_node *entry, u64 size)	\
 DECLARE_NEXT_HOLE_ADDR(next_hole_high_addr, rb_left, rb_right)
 DECLARE_NEXT_HOLE_ADDR(next_hole_low_addr, rb_right, rb_left)
 
-static struct drm_mm_node *
-next_hole(struct drm_mm *mm,
-	  struct drm_mm_node *node,
-	  u64 size,
-	  enum drm_mm_insert_mode mode)
+struct drm_mm_node *
+drm_mm_next_hole(struct drm_mm *mm,
+		 struct drm_mm_node *node,
+		 u64 size,
+		 enum drm_mm_insert_mode mode)
 {
 	switch (mode) {
 	default:
@@ -432,6 +433,7 @@ next_hole(struct drm_mm *mm,
 		return &node->hole_stack == &mm->hole_stack ? NULL : node;
 	}
 }
+EXPORT_SYMBOL(drm_mm_next_hole);
 
 /**
  * drm_mm_reserve_node - insert an pre-initialized node
@@ -520,7 +522,6 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
 {
 	struct drm_mm_node *hole;
 	u64 remainder_mask;
-	bool once;
 
 	DRM_MM_BUG_ON(range_start > range_end);
 
@@ -533,13 +534,8 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
 	if (alignment <= 1)
 		alignment = 0;
 
-	once = mode & DRM_MM_INSERT_ONCE;
-	mode &= ~DRM_MM_INSERT_ONCE;
-
 	remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0;
-	for (hole = first_hole(mm, range_start, range_end, size, mode);
-	     hole;
-	     hole = once ? NULL : next_hole(mm, hole, size, mode)) {
+	drm_mm_for_each_best_hole(hole, mm, range_start, range_end, size, mode) {
 		u64 hole_start = __drm_mm_hole_node_start(hole);
 		u64 hole_end = hole_start + hole->hole_size;
 		u64 adj_start, adj_end;
diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
index ac33ba1b18bc..5055447697fa 100644
--- a/include/drm/drm_mm.h
+++ b/include/drm/drm_mm.h
@@ -322,6 +322,17 @@ static inline u64 __drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
 	return list_next_entry(hole_node, node_list)->start;
 }
 
+struct drm_mm_node *
+drm_mm_first_hole(struct drm_mm *mm,
+		  u64 start, u64 end, u64 size,
+		  enum drm_mm_insert_mode mode);
+
+struct drm_mm_node *
+drm_mm_next_hole(struct drm_mm *mm,
+		 struct drm_mm_node *node,
+		 u64 size,
+		 enum drm_mm_insert_mode mode);
+
 /**
  * drm_mm_hole_node_end - computes the end of the hole following @node
  * @hole_node: drm_mm_node which implicitly tracks the following hole
@@ -400,6 +411,27 @@ static inline u64 drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
 	     1 : 0; \
 	     pos = list_next_entry(pos, hole_stack))
 
+/**
+ * drm_mm_for_each_best_hole - iterator to optimally walk over all holes >= @size
+ * @pos: &drm_mm_node used internally to track progress
+ * @mm: &drm_mm allocator to walk
+ * @range_start: start of the allowed range for the allocation
+ * @range_end: end of the allowed range for the allocation
+ * @size: size of the allocation
+ * @mode: fine-tune the allocation search
+ *
+ * This iterator walks over all holes suitable for the allocation of given
+ * @size in a very efficient manner. It is implemented by calling
+ * drm_mm_first_hole() and drm_mm_next_hole() which identify the
+ * appropriate holes within the given range by efficently traversing the
+ * rbtree associated with @mm.
+ */
+#define drm_mm_for_each_best_hole(pos, mm, range_start, range_end, size, mode) \
+	for (pos = drm_mm_first_hole(mm, range_start, range_end, size, mode); \
+	     pos; \
+	     pos = mode & DRM_MM_INSERT_ONCE ? \
+	     NULL : drm_mm_next_hole(mm, hole, size, mode))
+
 /*
  * Basic range manager support (drm_mm.c)
  */
-- 
2.34.1

Re: [PATCH 1/2] drm/mm: Add an iterator to optimally walk over holes for an allocation

[Tvrtko Ursulin]

On 02/02/2022 01:13, Vivek Kasireddy wrote:
> This iterator relies on drm_mm_first_hole() and drm_mm_next_hole()
> functions to identify suitable holes for an allocation of a given
> size by efficently traversing the rbtree associated with the given
> allocator.
> 
> It replaces the for loop in drm_mm_insert_node_in_range() and can
> also be used by drm drivers to quickly identify holes of a certain
> size within a given range.
> 
> Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
> ---
>   drivers/gpu/drm/drm_mm.c | 28 ++++++++++++----------------
>   include/drm/drm_mm.h     | 32 ++++++++++++++++++++++++++++++++
>   2 files changed, 44 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> index 8257f9d4f619..416c849c10e5 100644
> --- a/drivers/gpu/drm/drm_mm.c
> +++ b/drivers/gpu/drm/drm_mm.c
> @@ -352,10 +352,10 @@ static struct drm_mm_node *find_hole_addr(struct drm_mm *mm, u64 addr, u64 size)
>   	return node;
>   }
>   
> -static struct drm_mm_node *
> -first_hole(struct drm_mm *mm,
> -	   u64 start, u64 end, u64 size,
> -	   enum drm_mm_insert_mode mode)
> +struct drm_mm_node *
> +drm_mm_first_hole(struct drm_mm *mm,
> +		  u64 start, u64 end, u64 size,
> +		  enum drm_mm_insert_mode mode)
>   {
>   	switch (mode) {
>   	default:
> @@ -374,6 +374,7 @@ first_hole(struct drm_mm *mm,
>   						hole_stack);
>   	}
>   }
> +EXPORT_SYMBOL(drm_mm_first_hole);
>   
>   /**
>    * DECLARE_NEXT_HOLE_ADDR - macro to declare next hole functions
> @@ -410,11 +411,11 @@ static struct drm_mm_node *name(struct drm_mm_node *entry, u64 size)	\
>   DECLARE_NEXT_HOLE_ADDR(next_hole_high_addr, rb_left, rb_right)
>   DECLARE_NEXT_HOLE_ADDR(next_hole_low_addr, rb_right, rb_left)
>   
> -static struct drm_mm_node *
> -next_hole(struct drm_mm *mm,
> -	  struct drm_mm_node *node,
> -	  u64 size,
> -	  enum drm_mm_insert_mode mode)
> +struct drm_mm_node *
> +drm_mm_next_hole(struct drm_mm *mm,
> +		 struct drm_mm_node *node,
> +		 u64 size,
> +		 enum drm_mm_insert_mode mode)
>   {
>   	switch (mode) {
>   	default:
> @@ -432,6 +433,7 @@ next_hole(struct drm_mm *mm,
>   		return &node->hole_stack == &mm->hole_stack ? NULL : node;
>   	}
>   }
> +EXPORT_SYMBOL(drm_mm_next_hole);

May need to add kerneldoc since first/next_hole are now exported, or 
perhaps double underscore them if DRM core allows that approach to kind 
of signify "it is exported by shouldn't really be used"? Question for 
dri-devel I guess.

>   
>   /**
>    * drm_mm_reserve_node - insert an pre-initialized node
> @@ -520,7 +522,6 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
>   {
>   	struct drm_mm_node *hole;
>   	u64 remainder_mask;
> -	bool once;
>   
>   	DRM_MM_BUG_ON(range_start > range_end);
>   
> @@ -533,13 +534,8 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
>   	if (alignment <= 1)
>   		alignment = 0;
>   
> -	once = mode & DRM_MM_INSERT_ONCE;
> -	mode &= ~DRM_MM_INSERT_ONCE;
> -
>   	remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0;
> -	for (hole = first_hole(mm, range_start, range_end, size, mode);
> -	     hole;
> -	     hole = once ? NULL : next_hole(mm, hole, size, mode)) {
> +	drm_mm_for_each_best_hole(hole, mm, range_start, range_end, size, mode) {
>   		u64 hole_start = __drm_mm_hole_node_start(hole);
>   		u64 hole_end = hole_start + hole->hole_size;
>   		u64 adj_start, adj_end;
> diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
> index ac33ba1b18bc..5055447697fa 100644
> --- a/include/drm/drm_mm.h
> +++ b/include/drm/drm_mm.h
> @@ -322,6 +322,17 @@ static inline u64 __drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
>   	return list_next_entry(hole_node, node_list)->start;
>   }
>   
> +struct drm_mm_node *
> +drm_mm_first_hole(struct drm_mm *mm,
> +		  u64 start, u64 end, u64 size,
> +		  enum drm_mm_insert_mode mode);
> +
> +struct drm_mm_node *
> +drm_mm_next_hole(struct drm_mm *mm,
> +		 struct drm_mm_node *node,
> +		 u64 size,
> +		 enum drm_mm_insert_mode mode);
> +
>   /**
>    * drm_mm_hole_node_end - computes the end of the hole following @node
>    * @hole_node: drm_mm_node which implicitly tracks the following hole
> @@ -400,6 +411,27 @@ static inline u64 drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
>   	     1 : 0; \
>   	     pos = list_next_entry(pos, hole_stack))
>   
> +/**
> + * drm_mm_for_each_best_hole - iterator to optimally walk over all holes >= @size
> + * @pos: &drm_mm_node used internally to track progress
> + * @mm: &drm_mm allocator to walk
> + * @range_start: start of the allowed range for the allocation
> + * @range_end: end of the allowed range for the allocation
> + * @size: size of the allocation
> + * @mode: fine-tune the allocation search
> + *
> + * This iterator walks over all holes suitable for the allocation of given
> + * @size in a very efficient manner. It is implemented by calling
> + * drm_mm_first_hole() and drm_mm_next_hole() which identify the
> + * appropriate holes within the given range by efficently traversing the
> + * rbtree associated with @mm.
> + */
> +#define drm_mm_for_each_best_hole(pos, mm, range_start, range_end, size, mode) \

Probably should not have "best" in the name since the mode is passed in 
by the caller.

> +	for (pos = drm_mm_first_hole(mm, range_start, range_end, size, mode); \
> +	     pos; \
> +	     pos = mode & DRM_MM_INSERT_ONCE ? \
> +	     NULL : drm_mm_next_hole(mm, hole, size, mode))

I think you would need to modify the first/next_hole to mask out 
DRM_MM_INSERT_ONCE, otherwise it probably does not work as it stands.

Regards,

Tvrtko

> +
>   /*
>    * Basic range manager support (drm_mm.c)
>    */

RE: [PATCH 1/2] drm/mm: Add an iterator to optimally walk over holes for an allocation

[Kasireddy, Vivek]

Hi Tvrtko,

> -----Original Message-----
> From: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Sent: Wednesday, February 02, 2022 5:04 AM
> To: Kasireddy, Vivek <vivek.kasireddy@intel.com>; dri-devel@lists.freedesktop.org
> Subject: Re: [PATCH 1/2] drm/mm: Add an iterator to optimally walk over holes for an
> allocation
> 
> 
> On 02/02/2022 01:13, Vivek Kasireddy wrote:
> > This iterator relies on drm_mm_first_hole() and drm_mm_next_hole()
> > functions to identify suitable holes for an allocation of a given
> > size by efficently traversing the rbtree associated with the given
> > allocator.
> >
> > It replaces the for loop in drm_mm_insert_node_in_range() and can
> > also be used by drm drivers to quickly identify holes of a certain
> > size within a given range.
> >
> > Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> > Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
> > ---
> >   drivers/gpu/drm/drm_mm.c | 28 ++++++++++++----------------
> >   include/drm/drm_mm.h     | 32 ++++++++++++++++++++++++++++++++
> >   2 files changed, 44 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> > index 8257f9d4f619..416c849c10e5 100644
> > --- a/drivers/gpu/drm/drm_mm.c
> > +++ b/drivers/gpu/drm/drm_mm.c
> > @@ -352,10 +352,10 @@ static struct drm_mm_node *find_hole_addr(struct drm_mm
> *mm, u64 addr, u64 size)
> >   	return node;
> >   }
> >
> > -static struct drm_mm_node *
> > -first_hole(struct drm_mm *mm,
> > -	   u64 start, u64 end, u64 size,
> > -	   enum drm_mm_insert_mode mode)
> > +struct drm_mm_node *
> > +drm_mm_first_hole(struct drm_mm *mm,
> > +		  u64 start, u64 end, u64 size,
> > +		  enum drm_mm_insert_mode mode)
> >   {
> >   	switch (mode) {
> >   	default:
> > @@ -374,6 +374,7 @@ first_hole(struct drm_mm *mm,
> >   						hole_stack);
> >   	}
> >   }
> > +EXPORT_SYMBOL(drm_mm_first_hole);
> >
> >   /**
> >    * DECLARE_NEXT_HOLE_ADDR - macro to declare next hole functions
> > @@ -410,11 +411,11 @@ static struct drm_mm_node *name(struct drm_mm_node
> *entry, u64 size)	\
> >   DECLARE_NEXT_HOLE_ADDR(next_hole_high_addr, rb_left, rb_right)
> >   DECLARE_NEXT_HOLE_ADDR(next_hole_low_addr, rb_right, rb_left)
> >
> > -static struct drm_mm_node *
> > -next_hole(struct drm_mm *mm,
> > -	  struct drm_mm_node *node,
> > -	  u64 size,
> > -	  enum drm_mm_insert_mode mode)
> > +struct drm_mm_node *
> > +drm_mm_next_hole(struct drm_mm *mm,
> > +		 struct drm_mm_node *node,
> > +		 u64 size,
> > +		 enum drm_mm_insert_mode mode)
> >   {
> >   	switch (mode) {
> >   	default:
> > @@ -432,6 +433,7 @@ next_hole(struct drm_mm *mm,
> >   		return &node->hole_stack == &mm->hole_stack ? NULL : node;
> >   	}
> >   }
> > +EXPORT_SYMBOL(drm_mm_next_hole);
> 
> May need to add kerneldoc since first/next_hole are now exported, or
> perhaps double underscore them if DRM core allows that approach to kind
> of signify "it is exported by shouldn't really be used"? Question for
> dri-devel I guess.
[Kasireddy, Vivek] Ok, will wait until Daniel or others on dri-devel weigh in.
However, it looks like double underscore is the way to go given how the
exported symbol __drm_mm_interval_first() is used.

> 
> >
> >   /**
> >    * drm_mm_reserve_node - insert an pre-initialized node
> > @@ -520,7 +522,6 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
> >   {
> >   	struct drm_mm_node *hole;
> >   	u64 remainder_mask;
> > -	bool once;
> >
> >   	DRM_MM_BUG_ON(range_start > range_end);
> >
> > @@ -533,13 +534,8 @@ int drm_mm_insert_node_in_range(struct drm_mm * const
> mm,
> >   	if (alignment <= 1)
> >   		alignment = 0;
> >
> > -	once = mode & DRM_MM_INSERT_ONCE;
> > -	mode &= ~DRM_MM_INSERT_ONCE;
> > -
> >   	remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0;
> > -	for (hole = first_hole(mm, range_start, range_end, size, mode);
> > -	     hole;
> > -	     hole = once ? NULL : next_hole(mm, hole, size, mode)) {
> > +	drm_mm_for_each_best_hole(hole, mm, range_start, range_end, size, mode) {
> >   		u64 hole_start = __drm_mm_hole_node_start(hole);
> >   		u64 hole_end = hole_start + hole->hole_size;
> >   		u64 adj_start, adj_end;
> > diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
> > index ac33ba1b18bc..5055447697fa 100644
> > --- a/include/drm/drm_mm.h
> > +++ b/include/drm/drm_mm.h
> > @@ -322,6 +322,17 @@ static inline u64 __drm_mm_hole_node_end(const struct
> drm_mm_node *hole_node)
> >   	return list_next_entry(hole_node, node_list)->start;
> >   }
> >
> > +struct drm_mm_node *
> > +drm_mm_first_hole(struct drm_mm *mm,
> > +		  u64 start, u64 end, u64 size,
> > +		  enum drm_mm_insert_mode mode);
> > +
> > +struct drm_mm_node *
> > +drm_mm_next_hole(struct drm_mm *mm,
> > +		 struct drm_mm_node *node,
> > +		 u64 size,
> > +		 enum drm_mm_insert_mode mode);
> > +
> >   /**
> >    * drm_mm_hole_node_end - computes the end of the hole following @node
> >    * @hole_node: drm_mm_node which implicitly tracks the following hole
> > @@ -400,6 +411,27 @@ static inline u64 drm_mm_hole_node_end(const struct
> drm_mm_node *hole_node)
> >   	     1 : 0; \
> >   	     pos = list_next_entry(pos, hole_stack))
> >
> > +/**
> > + * drm_mm_for_each_best_hole - iterator to optimally walk over all holes >= @size
> > + * @pos: &drm_mm_node used internally to track progress
> > + * @mm: &drm_mm allocator to walk
> > + * @range_start: start of the allowed range for the allocation
> > + * @range_end: end of the allowed range for the allocation
> > + * @size: size of the allocation
> > + * @mode: fine-tune the allocation search
> > + *
> > + * This iterator walks over all holes suitable for the allocation of given
> > + * @size in a very efficient manner. It is implemented by calling
> > + * drm_mm_first_hole() and drm_mm_next_hole() which identify the
> > + * appropriate holes within the given range by efficently traversing the
> > + * rbtree associated with @mm.
> > + */
> > +#define drm_mm_for_each_best_hole(pos, mm, range_start, range_end, size, mode) \
> 
> Probably should not have "best" in the name since the mode is passed in
> by the caller.
[Kasireddy, Vivek] How about drm_mm_for_each_suitable_hole(...)?

> 
> > +	for (pos = drm_mm_first_hole(mm, range_start, range_end, size, mode); \
> > +	     pos; \
> > +	     pos = mode & DRM_MM_INSERT_ONCE ? \
> > +	     NULL : drm_mm_next_hole(mm, hole, size, mode))
> 
> I think you would need to modify the first/next_hole to mask out
> DRM_MM_INSERT_ONCE, otherwise it probably does not work as it stands.
[Kasireddy, Vivek] Either that or I do the mask out in the macro itself:
#define drm_mm_for_each_best_hole(pos, mm, range_start, range_end, size, mode) \
        for (pos = drm_mm_first_hole(mm, range_start, range_end, size, \
                                     mode & ~DRM_MM_INSERT_ONCE); \
             pos; \
             pos = mode & DRM_MM_INSERT_ONCE ? \
             NULL : drm_mm_next_hole(mm, hole, size, \
                                     mode & ~DRM_MM_INSERT_ONCE))
and also take care of the locations where mode is checked in the loop.
Or, I could just retain the once bool and pass it to the macro. Not sure if this is ok
but there don't seem to be cleaner/elegant options.

Thanks,
Vivek


> 
> Regards,
> 
> Tvrtko
> 
> > +
> >   /*
> >    * Basic range manager support (drm_mm.c)
> >    */

[PATCH 1/2] drm/mm: Add an iterator to optimally walk over holes for an allocation (v2)

[Vivek Kasireddy]

This iterator relies on drm_mm_first_hole() and drm_mm_next_hole()
functions to identify suitable holes for an allocation of a given
size by efficiently traversing the rbtree associated with the given
allocator.

It replaces the for loop in drm_mm_insert_node_in_range() and can
also be used by drm drivers to quickly identify holes of a certain
size within a given range.

v2: (Tvrtko)
- Prepend a double underscore for the newly exported first/next_hole
- s/each_best_hole/each_suitable_hole/g
- Mask out DRM_MM_INSERT_ONCE from the mode before calling
  first/next_hole and elsewhere.

Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
---
 drivers/gpu/drm/drm_mm.c | 38 ++++++++++++++++++--------------------
 include/drm/drm_mm.h     | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index 8257f9d4f619..b6da1dffcfcb 100644
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -352,10 +352,10 @@ static struct drm_mm_node *find_hole_addr(struct drm_mm *mm, u64 addr, u64 size)
 	return node;
 }
 
-static struct drm_mm_node *
-first_hole(struct drm_mm *mm,
-	   u64 start, u64 end, u64 size,
-	   enum drm_mm_insert_mode mode)
+struct drm_mm_node *
+__drm_mm_first_hole(struct drm_mm *mm,
+		    u64 start, u64 end, u64 size,
+		    enum drm_mm_insert_mode mode)
 {
 	switch (mode) {
 	default:
@@ -374,6 +374,7 @@ first_hole(struct drm_mm *mm,
 						hole_stack);
 	}
 }
+EXPORT_SYMBOL(__drm_mm_first_hole);
 
 /**
  * DECLARE_NEXT_HOLE_ADDR - macro to declare next hole functions
@@ -410,11 +411,11 @@ static struct drm_mm_node *name(struct drm_mm_node *entry, u64 size)	\
 DECLARE_NEXT_HOLE_ADDR(next_hole_high_addr, rb_left, rb_right)
 DECLARE_NEXT_HOLE_ADDR(next_hole_low_addr, rb_right, rb_left)
 
-static struct drm_mm_node *
-next_hole(struct drm_mm *mm,
-	  struct drm_mm_node *node,
-	  u64 size,
-	  enum drm_mm_insert_mode mode)
+struct drm_mm_node *
+__drm_mm_next_hole(struct drm_mm *mm,
+		   struct drm_mm_node *node,
+		   u64 size,
+		   enum drm_mm_insert_mode mode)
 {
 	switch (mode) {
 	default:
@@ -432,6 +433,7 @@ next_hole(struct drm_mm *mm,
 		return &node->hole_stack == &mm->hole_stack ? NULL : node;
 	}
 }
+EXPORT_SYMBOL(__drm_mm_next_hole);
 
 /**
  * drm_mm_reserve_node - insert an pre-initialized node
@@ -520,7 +522,6 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
 {
 	struct drm_mm_node *hole;
 	u64 remainder_mask;
-	bool once;
 
 	DRM_MM_BUG_ON(range_start > range_end);
 
@@ -533,22 +534,19 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
 	if (alignment <= 1)
 		alignment = 0;
 
-	once = mode & DRM_MM_INSERT_ONCE;
-	mode &= ~DRM_MM_INSERT_ONCE;
-
 	remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0;
-	for (hole = first_hole(mm, range_start, range_end, size, mode);
-	     hole;
-	     hole = once ? NULL : next_hole(mm, hole, size, mode)) {
+	drm_mm_for_each_suitable_hole(hole, mm, range_start, range_end,
+				      size, mode) {
 		u64 hole_start = __drm_mm_hole_node_start(hole);
 		u64 hole_end = hole_start + hole->hole_size;
 		u64 adj_start, adj_end;
 		u64 col_start, col_end;
+		enum drm_mm_insert_mode placement = mode & ~DRM_MM_INSERT_ONCE;
 
-		if (mode == DRM_MM_INSERT_LOW && hole_start >= range_end)
+		if (placement == DRM_MM_INSERT_LOW && hole_start >= range_end)
 			break;
 
-		if (mode == DRM_MM_INSERT_HIGH && hole_end <= range_start)
+		if (placement == DRM_MM_INSERT_HIGH && hole_end <= range_start)
 			break;
 
 		col_start = hole_start;
@@ -562,7 +560,7 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
 		if (adj_end <= adj_start || adj_end - adj_start < size)
 			continue;
 
-		if (mode == DRM_MM_INSERT_HIGH)
+		if (placement == DRM_MM_INSERT_HIGH)
 			adj_start = adj_end - size;
 
 		if (alignment) {
@@ -574,7 +572,7 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
 				div64_u64_rem(adj_start, alignment, &rem);
 			if (rem) {
 				adj_start -= rem;
-				if (mode != DRM_MM_INSERT_HIGH)
+				if (placement != DRM_MM_INSERT_HIGH)
 					adj_start += alignment;
 
 				if (adj_start < max(col_start, range_start) ||
diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
index ac33ba1b18bc..777f659f9692 100644
--- a/include/drm/drm_mm.h
+++ b/include/drm/drm_mm.h
@@ -400,6 +400,42 @@ static inline u64 drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
 	     1 : 0; \
 	     pos = list_next_entry(pos, hole_stack))
 
+struct drm_mm_node *
+__drm_mm_first_hole(struct drm_mm *mm,
+		    u64 start, u64 end, u64 size,
+		    enum drm_mm_insert_mode mode);
+
+struct drm_mm_node *
+__drm_mm_next_hole(struct drm_mm *mm,
+		   struct drm_mm_node *node,
+		   u64 size,
+		   enum drm_mm_insert_mode mode);
+
+/**
+ * drm_mm_for_each_suitable_hole - iterator to optimally walk over all
+ * holes that can fit an allocation of the given @size.
+ * @pos: &drm_mm_node used internally to track progress
+ * @mm: &drm_mm allocator to walk
+ * @range_start: start of the allowed range for the allocation
+ * @range_end: end of the allowed range for the allocation
+ * @size: size of the allocation
+ * @mode: fine-tune the allocation search
+ *
+ * This iterator walks over all holes suitable for the allocation of given
+ * @size in a very efficient manner. It is implemented by calling
+ * drm_mm_first_hole() and drm_mm_next_hole() which identify the
+ * appropriate holes within the given range by efficiently traversing the
+ * rbtree associated with @mm.
+ */
+#define drm_mm_for_each_suitable_hole(pos, mm, range_start, range_end, \
+				      size, mode) \
+	for (pos = __drm_mm_first_hole(mm, range_start, range_end, size, \
+				       mode & ~DRM_MM_INSERT_ONCE); \
+	     pos; \
+	     pos = mode & DRM_MM_INSERT_ONCE ? \
+	     NULL : __drm_mm_next_hole(mm, hole, size, \
+				       mode & ~DRM_MM_INSERT_ONCE))
+
 /*
  * Basic range manager support (drm_mm.c)
  */
-- 
2.34.1

[Intel-gfx] [PATCH 1/2] drm/mm: Add an iterator to optimally walk over holes for an allocation (v2)

[Vivek Kasireddy]

This iterator relies on drm_mm_first_hole() and drm_mm_next_hole()
functions to identify suitable holes for an allocation of a given
size by efficiently traversing the rbtree associated with the given
allocator.

It replaces the for loop in drm_mm_insert_node_in_range() and can
also be used by drm drivers to quickly identify holes of a certain
size within a given range.

v2: (Tvrtko)
- Prepend a double underscore for the newly exported first/next_hole
- s/each_best_hole/each_suitable_hole/g
- Mask out DRM_MM_INSERT_ONCE from the mode before calling
  first/next_hole and elsewhere.

Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
---
 drivers/gpu/drm/drm_mm.c | 38 ++++++++++++++++++--------------------
 include/drm/drm_mm.h     | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index 8257f9d4f619..b6da1dffcfcb 100644
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -352,10 +352,10 @@ static struct drm_mm_node *find_hole_addr(struct drm_mm *mm, u64 addr, u64 size)
 	return node;
 }
 
-static struct drm_mm_node *
-first_hole(struct drm_mm *mm,
-	   u64 start, u64 end, u64 size,
-	   enum drm_mm_insert_mode mode)
+struct drm_mm_node *
+__drm_mm_first_hole(struct drm_mm *mm,
+		    u64 start, u64 end, u64 size,
+		    enum drm_mm_insert_mode mode)
 {
 	switch (mode) {
 	default:
@@ -374,6 +374,7 @@ first_hole(struct drm_mm *mm,
 						hole_stack);
 	}
 }
+EXPORT_SYMBOL(__drm_mm_first_hole);
 
 /**
  * DECLARE_NEXT_HOLE_ADDR - macro to declare next hole functions
@@ -410,11 +411,11 @@ static struct drm_mm_node *name(struct drm_mm_node *entry, u64 size)	\
 DECLARE_NEXT_HOLE_ADDR(next_hole_high_addr, rb_left, rb_right)
 DECLARE_NEXT_HOLE_ADDR(next_hole_low_addr, rb_right, rb_left)
 
-static struct drm_mm_node *
-next_hole(struct drm_mm *mm,
-	  struct drm_mm_node *node,
-	  u64 size,
-	  enum drm_mm_insert_mode mode)
+struct drm_mm_node *
+__drm_mm_next_hole(struct drm_mm *mm,
+		   struct drm_mm_node *node,
+		   u64 size,
+		   enum drm_mm_insert_mode mode)
 {
 	switch (mode) {
 	default:
@@ -432,6 +433,7 @@ next_hole(struct drm_mm *mm,
 		return &node->hole_stack == &mm->hole_stack ? NULL : node;
 	}
 }
+EXPORT_SYMBOL(__drm_mm_next_hole);
 
 /**
  * drm_mm_reserve_node - insert an pre-initialized node
@@ -520,7 +522,6 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
 {
 	struct drm_mm_node *hole;
 	u64 remainder_mask;
-	bool once;
 
 	DRM_MM_BUG_ON(range_start > range_end);
 
@@ -533,22 +534,19 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
 	if (alignment <= 1)
 		alignment = 0;
 
-	once = mode & DRM_MM_INSERT_ONCE;
-	mode &= ~DRM_MM_INSERT_ONCE;
-
 	remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0;
-	for (hole = first_hole(mm, range_start, range_end, size, mode);
-	     hole;
-	     hole = once ? NULL : next_hole(mm, hole, size, mode)) {
+	drm_mm_for_each_suitable_hole(hole, mm, range_start, range_end,
+				      size, mode) {
 		u64 hole_start = __drm_mm_hole_node_start(hole);
 		u64 hole_end = hole_start + hole->hole_size;
 		u64 adj_start, adj_end;
 		u64 col_start, col_end;
+		enum drm_mm_insert_mode placement = mode & ~DRM_MM_INSERT_ONCE;
 
-		if (mode == DRM_MM_INSERT_LOW && hole_start >= range_end)
+		if (placement == DRM_MM_INSERT_LOW && hole_start >= range_end)
 			break;
 
-		if (mode == DRM_MM_INSERT_HIGH && hole_end <= range_start)
+		if (placement == DRM_MM_INSERT_HIGH && hole_end <= range_start)
 			break;
 
 		col_start = hole_start;
@@ -562,7 +560,7 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
 		if (adj_end <= adj_start || adj_end - adj_start < size)
 			continue;
 
-		if (mode == DRM_MM_INSERT_HIGH)
+		if (placement == DRM_MM_INSERT_HIGH)
 			adj_start = adj_end - size;
 
 		if (alignment) {
@@ -574,7 +572,7 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
 				div64_u64_rem(adj_start, alignment, &rem);
 			if (rem) {
 				adj_start -= rem;
-				if (mode != DRM_MM_INSERT_HIGH)
+				if (placement != DRM_MM_INSERT_HIGH)
 					adj_start += alignment;
 
 				if (adj_start < max(col_start, range_start) ||
diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
index ac33ba1b18bc..777f659f9692 100644
--- a/include/drm/drm_mm.h
+++ b/include/drm/drm_mm.h
@@ -400,6 +400,42 @@ static inline u64 drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
 	     1 : 0; \
 	     pos = list_next_entry(pos, hole_stack))
 
+struct drm_mm_node *
+__drm_mm_first_hole(struct drm_mm *mm,
+		    u64 start, u64 end, u64 size,
+		    enum drm_mm_insert_mode mode);
+
+struct drm_mm_node *
+__drm_mm_next_hole(struct drm_mm *mm,
+		   struct drm_mm_node *node,
+		   u64 size,
+		   enum drm_mm_insert_mode mode);
+
+/**
+ * drm_mm_for_each_suitable_hole - iterator to optimally walk over all
+ * holes that can fit an allocation of the given @size.
+ * @pos: &drm_mm_node used internally to track progress
+ * @mm: &drm_mm allocator to walk
+ * @range_start: start of the allowed range for the allocation
+ * @range_end: end of the allowed range for the allocation
+ * @size: size of the allocation
+ * @mode: fine-tune the allocation search
+ *
+ * This iterator walks over all holes suitable for the allocation of given
+ * @size in a very efficient manner. It is implemented by calling
+ * drm_mm_first_hole() and drm_mm_next_hole() which identify the
+ * appropriate holes within the given range by efficiently traversing the
+ * rbtree associated with @mm.
+ */
+#define drm_mm_for_each_suitable_hole(pos, mm, range_start, range_end, \
+				      size, mode) \
+	for (pos = __drm_mm_first_hole(mm, range_start, range_end, size, \
+				       mode & ~DRM_MM_INSERT_ONCE); \
+	     pos; \
+	     pos = mode & DRM_MM_INSERT_ONCE ? \
+	     NULL : __drm_mm_next_hole(mm, hole, size, \
+				       mode & ~DRM_MM_INSERT_ONCE))
+
 /*
  * Basic range manager support (drm_mm.c)
  */
-- 
2.34.1

Re: [PATCH 1/2] drm/mm: Add an iterator to optimally walk over holes for an allocation (v2)

[Tvrtko Ursulin]

On 04/02/2022 01:19, Vivek Kasireddy wrote:
> This iterator relies on drm_mm_first_hole() and drm_mm_next_hole()
> functions to identify suitable holes for an allocation of a given
> size by efficiently traversing the rbtree associated with the given
> allocator.
> 
> It replaces the for loop in drm_mm_insert_node_in_range() and can
> also be used by drm drivers to quickly identify holes of a certain
> size within a given range.
> 
> v2: (Tvrtko)
> - Prepend a double underscore for the newly exported first/next_hole
> - s/each_best_hole/each_suitable_hole/g
> - Mask out DRM_MM_INSERT_ONCE from the mode before calling
>    first/next_hole and elsewhere.
> 
> Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
> ---
>   drivers/gpu/drm/drm_mm.c | 38 ++++++++++++++++++--------------------
>   include/drm/drm_mm.h     | 36 ++++++++++++++++++++++++++++++++++++
>   2 files changed, 54 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> index 8257f9d4f619..b6da1dffcfcb 100644
> --- a/drivers/gpu/drm/drm_mm.c
> +++ b/drivers/gpu/drm/drm_mm.c
> @@ -352,10 +352,10 @@ static struct drm_mm_node *find_hole_addr(struct drm_mm *mm, u64 addr, u64 size)
>   	return node;
>   }
>   
> -static struct drm_mm_node *
> -first_hole(struct drm_mm *mm,
> -	   u64 start, u64 end, u64 size,
> -	   enum drm_mm_insert_mode mode)
> +struct drm_mm_node *
> +__drm_mm_first_hole(struct drm_mm *mm,
> +		    u64 start, u64 end, u64 size,
> +		    enum drm_mm_insert_mode mode)
>   {
>   	switch (mode) {
>   	default:
> @@ -374,6 +374,7 @@ first_hole(struct drm_mm *mm,
>   						hole_stack);
>   	}
>   }
> +EXPORT_SYMBOL(__drm_mm_first_hole);
>   
>   /**
>    * DECLARE_NEXT_HOLE_ADDR - macro to declare next hole functions
> @@ -410,11 +411,11 @@ static struct drm_mm_node *name(struct drm_mm_node *entry, u64 size)	\
>   DECLARE_NEXT_HOLE_ADDR(next_hole_high_addr, rb_left, rb_right)
>   DECLARE_NEXT_HOLE_ADDR(next_hole_low_addr, rb_right, rb_left)
>   
> -static struct drm_mm_node *
> -next_hole(struct drm_mm *mm,
> -	  struct drm_mm_node *node,
> -	  u64 size,
> -	  enum drm_mm_insert_mode mode)
> +struct drm_mm_node *
> +__drm_mm_next_hole(struct drm_mm *mm,
> +		   struct drm_mm_node *node,
> +		   u64 size,
> +		   enum drm_mm_insert_mode mode)
>   {
>   	switch (mode) {
>   	default:
> @@ -432,6 +433,7 @@ next_hole(struct drm_mm *mm,
>   		return &node->hole_stack == &mm->hole_stack ? NULL : node;
>   	}
>   }
> +EXPORT_SYMBOL(__drm_mm_next_hole);
>   
>   /**
>    * drm_mm_reserve_node - insert an pre-initialized node
> @@ -520,7 +522,6 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
>   {
>   	struct drm_mm_node *hole;
>   	u64 remainder_mask;
> -	bool once;
>   
>   	DRM_MM_BUG_ON(range_start > range_end);
>   
> @@ -533,22 +534,19 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
>   	if (alignment <= 1)
>   		alignment = 0;
>   
> -	once = mode & DRM_MM_INSERT_ONCE;
> -	mode &= ~DRM_MM_INSERT_ONCE;
> -
>   	remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0;
> -	for (hole = first_hole(mm, range_start, range_end, size, mode);
> -	     hole;
> -	     hole = once ? NULL : next_hole(mm, hole, size, mode)) {
> +	drm_mm_for_each_suitable_hole(hole, mm, range_start, range_end,
> +				      size, mode) {
>   		u64 hole_start = __drm_mm_hole_node_start(hole);
>   		u64 hole_end = hole_start + hole->hole_size;
>   		u64 adj_start, adj_end;
>   		u64 col_start, col_end;
> +		enum drm_mm_insert_mode placement = mode & ~DRM_MM_INSERT_ONCE;

Could move outside the loop, but not sure if it matters much.

Could also call the masked out variable mode and the passed in one 
caller_mode, or something, and that way have a smaller diff. (Four 
following hunks wouldn't be there.)

>   
> -		if (mode == DRM_MM_INSERT_LOW && hole_start >= range_end)
> +		if (placement == DRM_MM_INSERT_LOW && hole_start >= range_end)
>   			break;
>   
> -		if (mode == DRM_MM_INSERT_HIGH && hole_end <= range_start)
> +		if (placement == DRM_MM_INSERT_HIGH && hole_end <= range_start)
>   			break;
>   
>   		col_start = hole_start;
> @@ -562,7 +560,7 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
>   		if (adj_end <= adj_start || adj_end - adj_start < size)
>   			continue;
>   
> -		if (mode == DRM_MM_INSERT_HIGH)
> +		if (placement == DRM_MM_INSERT_HIGH)
>   			adj_start = adj_end - size;
>   
>   		if (alignment) {
> @@ -574,7 +572,7 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
>   				div64_u64_rem(adj_start, alignment, &rem);
>   			if (rem) {
>   				adj_start -= rem;
> -				if (mode != DRM_MM_INSERT_HIGH)
> +				if (placement != DRM_MM_INSERT_HIGH)
>   					adj_start += alignment;
>   
>   				if (adj_start < max(col_start, range_start) ||
> diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
> index ac33ba1b18bc..777f659f9692 100644
> --- a/include/drm/drm_mm.h
> +++ b/include/drm/drm_mm.h
> @@ -400,6 +400,42 @@ static inline u64 drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
>   	     1 : 0; \
>   	     pos = list_next_entry(pos, hole_stack))
>   
> +struct drm_mm_node *
> +__drm_mm_first_hole(struct drm_mm *mm,
> +		    u64 start, u64 end, u64 size,
> +		    enum drm_mm_insert_mode mode);
> +
> +struct drm_mm_node *
> +__drm_mm_next_hole(struct drm_mm *mm,
> +		   struct drm_mm_node *node,
> +		   u64 size,
> +		   enum drm_mm_insert_mode mode);
> +
> +/**
> + * drm_mm_for_each_suitable_hole - iterator to optimally walk over all
> + * holes that can fit an allocation of the given @size.
> + * @pos: &drm_mm_node used internally to track progress
> + * @mm: &drm_mm allocator to walk
> + * @range_start: start of the allowed range for the allocation
> + * @range_end: end of the allowed range for the allocation
> + * @size: size of the allocation
> + * @mode: fine-tune the allocation search
> + *
> + * This iterator walks over all holes suitable for the allocation of given
> + * @size in a very efficient manner. It is implemented by calling
> + * drm_mm_first_hole() and drm_mm_next_hole() which identify the
> + * appropriate holes within the given range by efficiently traversing the
> + * rbtree associated with @mm.
> + */
> +#define drm_mm_for_each_suitable_hole(pos, mm, range_start, range_end, \
> +				      size, mode) \
> +	for (pos = __drm_mm_first_hole(mm, range_start, range_end, size, \
> +				       mode & ~DRM_MM_INSERT_ONCE); \
> +	     pos; \
> +	     pos = mode & DRM_MM_INSERT_ONCE ? \
> +	     NULL : __drm_mm_next_hole(mm, hole, size, \
> +				       mode & ~DRM_MM_INSERT_ONCE))
> +
>   /*
>    * Basic range manager support (drm_mm.c)
>    */

Nitpicks/bikesheds or not, patch LGTM.

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Adding Christian and Das to Cc, by the virtue of being last people 
active in the hole area (!). :)

Regards,

Tvrtko

Re: [Intel-gfx] [PATCH 1/2] drm/mm: Add an iterator to optimally walk over holes for an allocation (v2)

[Tvrtko Ursulin]

On 04/02/2022 01:19, Vivek Kasireddy wrote:
> This iterator relies on drm_mm_first_hole() and drm_mm_next_hole()
> functions to identify suitable holes for an allocation of a given
> size by efficiently traversing the rbtree associated with the given
> allocator.
> 
> It replaces the for loop in drm_mm_insert_node_in_range() and can
> also be used by drm drivers to quickly identify holes of a certain
> size within a given range.
> 
> v2: (Tvrtko)
> - Prepend a double underscore for the newly exported first/next_hole
> - s/each_best_hole/each_suitable_hole/g
> - Mask out DRM_MM_INSERT_ONCE from the mode before calling
>    first/next_hole and elsewhere.
> 
> Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
> ---
>   drivers/gpu/drm/drm_mm.c | 38 ++++++++++++++++++--------------------
>   include/drm/drm_mm.h     | 36 ++++++++++++++++++++++++++++++++++++
>   2 files changed, 54 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> index 8257f9d4f619..b6da1dffcfcb 100644
> --- a/drivers/gpu/drm/drm_mm.c
> +++ b/drivers/gpu/drm/drm_mm.c
> @@ -352,10 +352,10 @@ static struct drm_mm_node *find_hole_addr(struct drm_mm *mm, u64 addr, u64 size)
>   	return node;
>   }
>   
> -static struct drm_mm_node *
> -first_hole(struct drm_mm *mm,
> -	   u64 start, u64 end, u64 size,
> -	   enum drm_mm_insert_mode mode)
> +struct drm_mm_node *
> +__drm_mm_first_hole(struct drm_mm *mm,
> +		    u64 start, u64 end, u64 size,
> +		    enum drm_mm_insert_mode mode)
>   {
>   	switch (mode) {
>   	default:
> @@ -374,6 +374,7 @@ first_hole(struct drm_mm *mm,
>   						hole_stack);
>   	}
>   }
> +EXPORT_SYMBOL(__drm_mm_first_hole);
>   
>   /**
>    * DECLARE_NEXT_HOLE_ADDR - macro to declare next hole functions
> @@ -410,11 +411,11 @@ static struct drm_mm_node *name(struct drm_mm_node *entry, u64 size)	\
>   DECLARE_NEXT_HOLE_ADDR(next_hole_high_addr, rb_left, rb_right)
>   DECLARE_NEXT_HOLE_ADDR(next_hole_low_addr, rb_right, rb_left)
>   
> -static struct drm_mm_node *
> -next_hole(struct drm_mm *mm,
> -	  struct drm_mm_node *node,
> -	  u64 size,
> -	  enum drm_mm_insert_mode mode)
> +struct drm_mm_node *
> +__drm_mm_next_hole(struct drm_mm *mm,
> +		   struct drm_mm_node *node,
> +		   u64 size,
> +		   enum drm_mm_insert_mode mode)
>   {
>   	switch (mode) {
>   	default:
> @@ -432,6 +433,7 @@ next_hole(struct drm_mm *mm,
>   		return &node->hole_stack == &mm->hole_stack ? NULL : node;
>   	}
>   }
> +EXPORT_SYMBOL(__drm_mm_next_hole);
>   
>   /**
>    * drm_mm_reserve_node - insert an pre-initialized node
> @@ -520,7 +522,6 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
>   {
>   	struct drm_mm_node *hole;
>   	u64 remainder_mask;
> -	bool once;
>   
>   	DRM_MM_BUG_ON(range_start > range_end);
>   
> @@ -533,22 +534,19 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
>   	if (alignment <= 1)
>   		alignment = 0;
>   
> -	once = mode & DRM_MM_INSERT_ONCE;
> -	mode &= ~DRM_MM_INSERT_ONCE;
> -
>   	remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0;
> -	for (hole = first_hole(mm, range_start, range_end, size, mode);
> -	     hole;
> -	     hole = once ? NULL : next_hole(mm, hole, size, mode)) {
> +	drm_mm_for_each_suitable_hole(hole, mm, range_start, range_end,
> +				      size, mode) {
>   		u64 hole_start = __drm_mm_hole_node_start(hole);
>   		u64 hole_end = hole_start + hole->hole_size;
>   		u64 adj_start, adj_end;
>   		u64 col_start, col_end;
> +		enum drm_mm_insert_mode placement = mode & ~DRM_MM_INSERT_ONCE;

Could move outside the loop, but not sure if it matters much.

Could also call the masked out variable mode and the passed in one 
caller_mode, or something, and that way have a smaller diff. (Four 
following hunks wouldn't be there.)

>   
> -		if (mode == DRM_MM_INSERT_LOW && hole_start >= range_end)
> +		if (placement == DRM_MM_INSERT_LOW && hole_start >= range_end)
>   			break;
>   
> -		if (mode == DRM_MM_INSERT_HIGH && hole_end <= range_start)
> +		if (placement == DRM_MM_INSERT_HIGH && hole_end <= range_start)
>   			break;
>   
>   		col_start = hole_start;
> @@ -562,7 +560,7 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
>   		if (adj_end <= adj_start || adj_end - adj_start < size)
>   			continue;
>   
> -		if (mode == DRM_MM_INSERT_HIGH)
> +		if (placement == DRM_MM_INSERT_HIGH)
>   			adj_start = adj_end - size;
>   
>   		if (alignment) {
> @@ -574,7 +572,7 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
>   				div64_u64_rem(adj_start, alignment, &rem);
>   			if (rem) {
>   				adj_start -= rem;
> -				if (mode != DRM_MM_INSERT_HIGH)
> +				if (placement != DRM_MM_INSERT_HIGH)
>   					adj_start += alignment;
>   
>   				if (adj_start < max(col_start, range_start) ||
> diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
> index ac33ba1b18bc..777f659f9692 100644
> --- a/include/drm/drm_mm.h
> +++ b/include/drm/drm_mm.h
> @@ -400,6 +400,42 @@ static inline u64 drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
>   	     1 : 0; \
>   	     pos = list_next_entry(pos, hole_stack))
>   
> +struct drm_mm_node *
> +__drm_mm_first_hole(struct drm_mm *mm,
> +		    u64 start, u64 end, u64 size,
> +		    enum drm_mm_insert_mode mode);
> +
> +struct drm_mm_node *
> +__drm_mm_next_hole(struct drm_mm *mm,
> +		   struct drm_mm_node *node,
> +		   u64 size,
> +		   enum drm_mm_insert_mode mode);
> +
> +/**
> + * drm_mm_for_each_suitable_hole - iterator to optimally walk over all
> + * holes that can fit an allocation of the given @size.
> + * @pos: &drm_mm_node used internally to track progress
> + * @mm: &drm_mm allocator to walk
> + * @range_start: start of the allowed range for the allocation
> + * @range_end: end of the allowed range for the allocation
> + * @size: size of the allocation
> + * @mode: fine-tune the allocation search
> + *
> + * This iterator walks over all holes suitable for the allocation of given
> + * @size in a very efficient manner. It is implemented by calling
> + * drm_mm_first_hole() and drm_mm_next_hole() which identify the
> + * appropriate holes within the given range by efficiently traversing the
> + * rbtree associated with @mm.
> + */
> +#define drm_mm_for_each_suitable_hole(pos, mm, range_start, range_end, \
> +				      size, mode) \
> +	for (pos = __drm_mm_first_hole(mm, range_start, range_end, size, \
> +				       mode & ~DRM_MM_INSERT_ONCE); \
> +	     pos; \
> +	     pos = mode & DRM_MM_INSERT_ONCE ? \
> +	     NULL : __drm_mm_next_hole(mm, hole, size, \
> +				       mode & ~DRM_MM_INSERT_ONCE))
> +
>   /*
>    * Basic range manager support (drm_mm.c)
>    */

Nitpicks/bikesheds or not, patch LGTM.

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Adding Christian and Das to Cc, by the virtue of being last people 
active in the hole area (!). :)

Regards,

Tvrtko