drm/nouveau/core/mm: replace region list with next pointer

We never have any need for a double-linked list here, and as there's
generally a large number of these objects, replace it with a single-
linked list in order to save some memory.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/include/nvkm/core/mm.h

@@ -5,7 +5,7 @@
 struct nvkm_mm_node {
 	struct list_head nl_entry;
 	struct list_head fl_entry;
-	struct list_head rl_entry;
+	struct nvkm_mm_node *next;
 
 #define NVKM_MM_HEAP_ANY 0x00
 	u8  heap;
@@ -38,4 +38,10 @@ int  nvkm_mm_tail(struct nvkm_mm *, u8 heap, u8 type, u32 size_max,
 		  u32 size_min, u32 align, struct nvkm_mm_node **);
 void nvkm_mm_free(struct nvkm_mm *, struct nvkm_mm_node **);
 void nvkm_mm_dump(struct nvkm_mm *, const char *);
+
+static inline bool
+nvkm_mm_contiguous(struct nvkm_mm_node *node)
+{
+	return !node->next;
+}
 #endif

drivers/gpu/drm/nouveau/include/nvkm/subdev/fb.h

@@ -29,7 +29,7 @@ struct nvkm_mem {
 	u8  page_shift;
 
 	struct nvkm_mm_node *tag;
-	struct list_head regions;
+	struct nvkm_mm_node *mem;
 	dma_addr_t *pages;
 	u32 memtype;
 	u64 offset;

drivers/gpu/drm/nouveau/nouveau_bo.c

@@ -321,7 +321,7 @@ nouveau_bo_pin(struct nouveau_bo *nvbo, uint32_t memtype, bool contig)
 		if (nvbo->tile_flags & NOUVEAU_GEM_TILE_NONCONTIG) {
 			if (bo->mem.mem_type == TTM_PL_VRAM) {
 				struct nvkm_mem *mem = bo->mem.mm_node;
-				if (!list_is_singular(&mem->regions))
+				if (!nvkm_mm_contiguous(mem->mem))
 					evict = true;
 			}
 			nvbo->tile_flags &= ~NOUVEAU_GEM_TILE_NONCONTIG;

drivers/gpu/drm/nouveau/nvkm/core/mm.c

@@ -147,6 +147,7 @@ nvkm_mm_head(struct nvkm_mm *mm, u8 heap, u8 type, u32 size_max, u32 size_min,
 		if (!this)
 			return -ENOMEM;
 
+		this->next = NULL;
 		this->type = type;
 		list_del(&this->fl_entry);
 		*pnode = this;
@@ -225,6 +226,7 @@ nvkm_mm_tail(struct nvkm_mm *mm, u8 heap, u8 type, u32 size_max, u32 size_min,
 		if (!this)
 			return -ENOMEM;
 
+		this->next = NULL;
 		this->type = type;
 		list_del(&this->fl_entry);
 		*pnode = this;

drivers/gpu/drm/nouveau/nvkm/subdev/fb/ramgf100.c

@@ -445,7 +445,7 @@ gf100_ram_get(struct nvkm_ram *ram, u64 size, u32 align, u32 ncmin,
 {
 	struct nvkm_ltc *ltc = ram->fb->subdev.device->ltc;
 	struct nvkm_mm *mm = &ram->vram;
-	struct nvkm_mm_node *r;
+	struct nvkm_mm_node **node, *r;
 	struct nvkm_mem *mem;
 	int type = (memtype & 0x0ff);
 	int back = (memtype & 0x800);
@@ -462,7 +462,6 @@ gf100_ram_get(struct nvkm_ram *ram, u64 size, u32 align, u32 ncmin,
 	if (!mem)
 		return -ENOMEM;
 
-	INIT_LIST_HEAD(&mem->regions);
 	mem->size = size;
 
 	mutex_lock(&ram->fb->subdev.mutex);
@@ -478,6 +477,7 @@ gf100_ram_get(struct nvkm_ram *ram, u64 size, u32 align, u32 ncmin,
 	}
 	mem->memtype = type;
 
+	node = &mem->mem;
 	do {
 		if (back)
 			ret = nvkm_mm_tail(mm, 0, 1, size, ncmin, align, &r);
@@ -489,13 +489,13 @@ gf100_ram_get(struct nvkm_ram *ram, u64 size, u32 align, u32 ncmin,
 			return ret;
 		}
 
-		list_add_tail(&r->rl_entry, &mem->regions);
+		*node = r;
+		node = &r->next;
 		size -= r->length;
 	} while (size);
 	mutex_unlock(&ram->fb->subdev.mutex);
 
-	r = list_first_entry(&mem->regions, struct nvkm_mm_node, rl_entry);
-	mem->offset = (u64)r->offset << NVKM_RAM_MM_SHIFT;
+	mem->offset = (u64)mem->mem->offset << NVKM_RAM_MM_SHIFT;
 	*pmem = mem;
 	return 0;
 }

drivers/gpu/drm/nouveau/nvkm/subdev/fb/ramnv50.c

@@ -496,15 +496,12 @@ nv50_ram_tidy(struct nvkm_ram *base)
 void
 __nv50_ram_put(struct nvkm_ram *ram, struct nvkm_mem *mem)
 {
-	struct nvkm_mm_node *this;
-
-	while (!list_empty(&mem->regions)) {
-		this = list_first_entry(&mem->regions, typeof(*this), rl_entry);
-
-		list_del(&this->rl_entry);
-		nvkm_mm_free(&ram->vram, &this);
+	struct nvkm_mm_node *next = mem->mem;
+	struct nvkm_mm_node *node;
+	while ((node = next)) {
+		next = node->next;
+		nvkm_mm_free(&ram->vram, &node);
 	}
-
 	nvkm_mm_free(&ram->tags, &mem->tag);
 }
 
@@ -530,7 +527,7 @@ nv50_ram_get(struct nvkm_ram *ram, u64 size, u32 align, u32 ncmin,
 {
 	struct nvkm_mm *heap = &ram->vram;
 	struct nvkm_mm *tags = &ram->tags;
-	struct nvkm_mm_node *r;
+	struct nvkm_mm_node **node, *r;
 	struct nvkm_mem *mem;
 	int comp = (memtype & 0x300) >> 8;
 	int type = (memtype & 0x07f);
@@ -559,11 +556,11 @@ nv50_ram_get(struct nvkm_ram *ram, u64 size, u32 align, u32 ncmin,
 			comp = 0;
 	}
 
-	INIT_LIST_HEAD(&mem->regions);
 	mem->memtype = (comp << 7) | type;
 	mem->size = max;
 
 	type = nv50_fb_memtype[type];
+	node = &mem->mem;
 	do {
 		if (back)
 			ret = nvkm_mm_tail(heap, 0, type, max, min, align, &r);
@@ -575,13 +572,13 @@ nv50_ram_get(struct nvkm_ram *ram, u64 size, u32 align, u32 ncmin,
 			return ret;
 		}
 
-		list_add_tail(&r->rl_entry, &mem->regions);
+		*node = r;
+		node = &r->next;
 		max -= r->length;
 	} while (max);
 	mutex_unlock(&ram->fb->subdev.mutex);
 
-	r = list_first_entry(&mem->regions, struct nvkm_mm_node, rl_entry);
-	mem->offset = (u64)r->offset << NVKM_RAM_MM_SHIFT;
+	mem->offset = (u64)mem->mem->offset << NVKM_RAM_MM_SHIFT;
 	*pmem = mem;
 	return 0;
 }

drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c

@@ -305,11 +305,11 @@ gk20a_instobj_dtor_iommu(struct nvkm_memory *memory)
 	struct gk20a_instobj_iommu *node = gk20a_instobj_iommu(memory);
 	struct gk20a_instmem *imem = node->base.imem;
 	struct device *dev = imem->base.subdev.device->dev;
-	struct nvkm_mm_node *r;
+	struct nvkm_mm_node *r = node->base.mem.mem;
 	unsigned long flags;
 	int i;
 
-	if (unlikely(list_empty(&node->base.mem.regions)))
+	if (unlikely(!r))
 		goto out;
 
 	spin_lock_irqsave(&imem->lock, flags);
@@ -320,9 +320,6 @@ gk20a_instobj_dtor_iommu(struct nvkm_memory *memory)
 
 	spin_unlock_irqrestore(&imem->lock, flags);
 
-	r = list_first_entry(&node->base.mem.regions, struct nvkm_mm_node,
-			     rl_entry);
-
 	/* clear IOMMU bit to unmap pages */
 	r->offset &= ~BIT(imem->iommu_bit - imem->iommu_pgshift);
 
@@ -404,10 +401,7 @@ gk20a_instobj_ctor_dma(struct gk20a_instmem *imem, u32 npages, u32 align,
 	node->r.length = (npages << PAGE_SHIFT) >> 12;
 
 	node->base.mem.offset = node->handle;
-
-	INIT_LIST_HEAD(&node->base.mem.regions);
-	list_add_tail(&node->r.rl_entry, &node->base.mem.regions);
-
+	node->base.mem.mem = &node->r;
 	return 0;
 }
 
@@ -484,10 +478,7 @@ gk20a_instobj_ctor_iommu(struct gk20a_instmem *imem, u32 npages, u32 align,
 	r->offset |= BIT(imem->iommu_bit - imem->iommu_pgshift);
 
 	node->base.mem.offset = ((u64)r->offset) << imem->iommu_pgshift;
-
-	INIT_LIST_HEAD(&node->base.mem.regions);
-	list_add_tail(&r->rl_entry, &node->base.mem.regions);
-
+	node->base.mem.mem = r;
 	return 0;
 
 release_area:

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/base.c

@@ -31,7 +31,7 @@ nvkm_vm_map_at(struct nvkm_vma *vma, u64 delta, struct nvkm_mem *node)
 {
 	struct nvkm_vm *vm = vma->vm;
 	struct nvkm_mmu *mmu = vm->mmu;
-	struct nvkm_mm_node *r;
+	struct nvkm_mm_node *r = node->mem;
 	int big = vma->node->type != mmu->func->spg_shift;
 	u32 offset = vma->node->offset + (delta >> 12);
 	u32 bits = vma->node->type - 12;
@@ -41,7 +41,7 @@ nvkm_vm_map_at(struct nvkm_vma *vma, u64 delta, struct nvkm_mem *node)
 	u32 end, len;
 
 	delta = 0;
-	list_for_each_entry(r, &node->regions, rl_entry) {
+	while (r) {
 		u64 phys = (u64)r->offset << 12;
 		u32 num  = r->length >> bits;
 
@@ -65,7 +65,8 @@ nvkm_vm_map_at(struct nvkm_vma *vma, u64 delta, struct nvkm_mem *node)
 
 			delta += (u64)len << vma->node->type;
 		}
-	}
+		r = r->next;
+	};
 
 	mmu->func->flush(vm);
 }