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>

2 files changed, 15 insertions, 18 deletions

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/fb/ramgf100.c b/drivers/gpu/drm/nouveau/nvkm/subdev/fb/ramgf100.c
index 093223d1df4f..6758da93a3a1 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/fb/ramgf100.c
+++ b/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;
 }
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/fb/ramnv50.c b/drivers/gpu/drm/nouveau/nvkm/subdev/fb/ramnv50.c
index 87bde8ff2d6b..6549b0588309 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/fb/ramnv50.c
+++ b/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;
 }