Re: [PATCH 4/5] drm/mm: Convert drm_mm_node booleans to bitops

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 03/10/2019 22:00, Chris Wilson wrote:
> A straightforward conversion of assignment and checking of the boolean
> state flags (allocated, scanned) into non-atomic bitops. The caller
> remains responsible for all locking around the drm_mm and its nodes.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/drm_mm.c                       | 18 +++++++++---------
>   drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c |  2 +-
>   drivers/gpu/drm/i915/i915_gem.c                |  4 ++--
>   include/drm/drm_mm.h                           |  7 ++++---
>   4 files changed, 16 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> index 99312bdc6273..a9cab5e53731 100644
> --- a/drivers/gpu/drm/drm_mm.c
> +++ b/drivers/gpu/drm/drm_mm.c
> @@ -426,7 +426,7 @@ int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node)
>   
>   	list_add(&node->node_list, &hole->node_list);
>   	drm_mm_interval_tree_add_node(hole, node);
> -	node->allocated = true;
> +	__set_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags);
>   	node->hole_size = 0;
>   
>   	rm_hole(hole);
> @@ -545,7 +545,7 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
>   
>   		list_add(&node->node_list, &hole->node_list);
>   		drm_mm_interval_tree_add_node(hole, node);
> -		node->allocated = true;
> +		__set_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags);
>   
>   		rm_hole(hole);
>   		if (adj_start > hole_start)
> @@ -563,7 +563,7 @@ EXPORT_SYMBOL(drm_mm_insert_node_in_range);
>   
>   static inline bool drm_mm_node_scanned_block(const struct drm_mm_node *node)
>   {
> -	return node->scanned_block;
> +	return test_bit(DRM_MM_NODE_SCANNED_BIT, &node->flags);
>   }
>   
>   /**
> @@ -589,7 +589,7 @@ void drm_mm_remove_node(struct drm_mm_node *node)
>   
>   	drm_mm_interval_tree_remove(node, &mm->interval_tree);
>   	list_del(&node->node_list);
> -	node->allocated = false;
> +	__clear_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags);
>   
>   	if (drm_mm_hole_follows(prev_node))
>   		rm_hole(prev_node);
> @@ -627,8 +627,8 @@ void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new)
>   				&mm->holes_addr);
>   	}
>   
> -	old->allocated = false;
> -	new->allocated = true;
> +	__clear_bit(DRM_MM_NODE_ALLOCATED_BIT, &old->flags);
> +	__set_bit(DRM_MM_NODE_ALLOCATED_BIT, &new->flags);
>   }
>   EXPORT_SYMBOL(drm_mm_replace_node);
>   
> @@ -738,7 +738,7 @@ bool drm_mm_scan_add_block(struct drm_mm_scan *scan,
>   	DRM_MM_BUG_ON(node->mm != mm);
>   	DRM_MM_BUG_ON(!drm_mm_node_allocated(node));
>   	DRM_MM_BUG_ON(drm_mm_node_scanned_block(node));
> -	node->scanned_block = true;
> +	__set_bit(DRM_MM_NODE_SCANNED_BIT, &node->flags);
>   	mm->scan_active++;
>   
>   	/* Remove this block from the node_list so that we enlarge the hole
> @@ -824,7 +824,7 @@ bool drm_mm_scan_remove_block(struct drm_mm_scan *scan,
>   
>   	DRM_MM_BUG_ON(node->mm != scan->mm);
>   	DRM_MM_BUG_ON(!drm_mm_node_scanned_block(node));
> -	node->scanned_block = false;
> +	__clear_bit(DRM_MM_NODE_SCANNED_BIT, &node->flags);
>   
>   	DRM_MM_BUG_ON(!node->mm->scan_active);
>   	node->mm->scan_active--;
> @@ -922,7 +922,7 @@ void drm_mm_init(struct drm_mm *mm, u64 start, u64 size)
>   
>   	/* Clever trick to avoid a special case in the free hole tracking. */
>   	INIT_LIST_HEAD(&mm->head_node.node_list);
> -	mm->head_node.allocated = false;
> +	mm->head_node.flags = 0;
>   	mm->head_node.mm = mm;
>   	mm->head_node.start = start + size;
>   	mm->head_node.size = -size;
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> index 20d8a6297985..c049199a1df5 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> @@ -906,7 +906,7 @@ static void reloc_cache_init(struct reloc_cache *cache,
>   	cache->use_64bit_reloc = HAS_64BIT_RELOC(i915);
>   	cache->has_fence = cache->gen < 4;
>   	cache->needs_unfenced = INTEL_INFO(i915)->unfenced_needs_alignment;
> -	cache->node.allocated = false;
> +	cache->node.flags = 0;
>   	cache->ce = NULL;
>   	cache->rq = NULL;
>   	cache->rq_size = 0;
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index fa8e028ac0b5..7046067f70c1 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -351,7 +351,7 @@ i915_gem_gtt_pread(struct drm_i915_gem_object *obj,
>   					       PIN_NOEVICT);
>   	if (!IS_ERR(vma)) {
>   		node.start = i915_ggtt_offset(vma);
> -		node.allocated = false;
> +		node.flags = 0;
>   	} else {
>   		ret = insert_mappable_node(ggtt, &node, PAGE_SIZE);
>   		if (ret)
> @@ -561,7 +561,7 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
>   					       PIN_NOEVICT);
>   	if (!IS_ERR(vma)) {
>   		node.start = i915_ggtt_offset(vma);
> -		node.allocated = false;
> +		node.flags = 0;
>   	} else {
>   		ret = insert_mappable_node(ggtt, &node, PAGE_SIZE);
>   		if (ret)
> diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
> index 2c3bbb43c7d1..d7939c054259 100644
> --- a/include/drm/drm_mm.h
> +++ b/include/drm/drm_mm.h
> @@ -168,8 +168,9 @@ struct drm_mm_node {
>   	struct rb_node rb_hole_addr;
>   	u64 __subtree_last;
>   	u64 hole_size;
> -	bool allocated : 1;
> -	bool scanned_block : 1;
> +	unsigned long flags;
> +#define DRM_MM_NODE_ALLOCATED_BIT	0
> +#define DRM_MM_NODE_SCANNED_BIT		1
>   #ifdef CONFIG_DRM_DEBUG_MM
>   	depot_stack_handle_t stack;
>   #endif
> @@ -253,7 +254,7 @@ struct drm_mm_scan {
>    */
>   static inline bool drm_mm_node_allocated(const struct drm_mm_node *node)
>   {
> -	return node->allocated;
> +	return test_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags);
>   }
>   
>   /**
> 

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

Regards,

Tvrtko
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