drm/nouveau/core/memory: add reference counting

We need to be able to prevent memory from being freed while it's still
mapped in a GPU's address-space.

Will be used by upcoming MMU changes.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

2 files changed, 24 insertions, 6 deletions

diff --git a/drivers/gpu/drm/nouveau/nvkm/core/gpuobj.c b/drivers/gpu/drm/nouveau/nvkm/core/gpuobj.c
index 1264d5fc632b..d6de2b3ed2c3 100644
--- a/drivers/gpu/drm/nouveau/nvkm/core/gpuobj.c
+++ b/drivers/gpu/drm/nouveau/nvkm/core/gpuobj.c
@@ -219,7 +219,7 @@ nvkm_gpuobj_del(struct nvkm_gpuobj **pgpuobj)
 		if (gpuobj->parent)
 			nvkm_mm_free(&gpuobj->parent->heap, &gpuobj->node);
 		nvkm_mm_fini(&gpuobj->heap);
-		nvkm_memory_del(&gpuobj->memory);
+		nvkm_memory_unref(&gpuobj->memory);
 		kfree(*pgpuobj);
 		*pgpuobj = NULL;
 	}
diff --git a/drivers/gpu/drm/nouveau/nvkm/core/memory.c b/drivers/gpu/drm/nouveau/nvkm/core/memory.c
index 13cfcdde99fd..29f4b4070b55 100644
--- a/drivers/gpu/drm/nouveau/nvkm/core/memory.c
+++ b/drivers/gpu/drm/nouveau/nvkm/core/memory.c
@@ -100,20 +100,38 @@ nvkm_memory_ctor(const struct nvkm_memory_func *func,
 		 struct nvkm_memory *memory)
 {
 	memory->func = func;
+	kref_init(&memory->kref);
+}
+
+static void
+nvkm_memory_del(struct kref *kref)
+{
+	struct nvkm_memory *memory = container_of(kref, typeof(*memory), kref);
+	if (!WARN_ON(!memory->func)) {
+		if (memory->func->dtor)
+			memory = memory->func->dtor(memory);
+		kfree(memory);
+	}
 }
 
 void
-nvkm_memory_del(struct nvkm_memory **pmemory)
+nvkm_memory_unref(struct nvkm_memory **pmemory)
 {
 	struct nvkm_memory *memory = *pmemory;
-	if (memory && !WARN_ON(!memory->func)) {
-		if (memory->func->dtor)
-			*pmemory = memory->func->dtor(memory);
-		kfree(*pmemory);
+	if (memory) {
+		kref_put(&memory->kref, nvkm_memory_del);
 		*pmemory = NULL;
 	}
 }
 
+struct nvkm_memory *
+nvkm_memory_ref(struct nvkm_memory *memory)
+{
+	if (memory)
+		kref_get(&memory->kref);
+	return memory;
+}
+
 int
 nvkm_memory_new(struct nvkm_device *device, enum nvkm_memory_target target,
 		u64 size, u32 align, bool zero,