drm/etnaviv: split obj locks in different classes depending on the obj type

Userptr, prime and shmem buffer objects have different lock ordering
requirements. This is mostly due to the fact that we don't allow to mmap
userptr buffers, so we won't ever end up in our fault handler for those,
so some of the code paths are never called with the mmap_sem held.

To avoid lockdep false positives, split them up into different lock classes.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>

drivers/gpu/drm/etnaviv/etnaviv_gem.c

@@ -24,6 +24,9 @@
 #include "etnaviv_gpu.h"
 #include "etnaviv_mmu.h"
 
+static struct lock_class_key etnaviv_shm_lock_class;
+static struct lock_class_key etnaviv_userptr_lock_class;
+
 static void etnaviv_gem_scatter_map(struct etnaviv_gem_object *etnaviv_obj)
 {
 	struct drm_device *dev = etnaviv_obj->base.dev;
@@ -653,6 +656,8 @@ static struct drm_gem_object *__etnaviv_gem_new(struct drm_device *dev,
 	if (ret)
 		goto fail;
 
+	lockdep_set_class(&to_etnaviv_bo(obj)->lock, &etnaviv_shm_lock_class);
+
 	ret = drm_gem_object_init(dev, obj, size);
 	if (ret == 0) {
 		struct address_space *mapping;
@@ -897,6 +902,8 @@ int etnaviv_gem_new_userptr(struct drm_device *dev, struct drm_file *file,
 	if (ret)
 		return ret;
 
+	lockdep_set_class(&etnaviv_obj->lock, &etnaviv_userptr_lock_class);
+
 	etnaviv_obj->userptr.ptr = ptr;
 	etnaviv_obj->userptr.task = current;
 	etnaviv_obj->userptr.ro = !(flags & ETNA_USERPTR_WRITE);

drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c

@@ -19,6 +19,7 @@
 #include "etnaviv_drv.h"
 #include "etnaviv_gem.h"
 
+static struct lock_class_key etnaviv_prime_lock_class;
 
 struct sg_table *etnaviv_gem_prime_get_sg_table(struct drm_gem_object *obj)
 {
@@ -125,6 +126,8 @@ struct drm_gem_object *etnaviv_gem_prime_import_sg_table(struct drm_device *dev,
 	if (ret < 0)
 		return ERR_PTR(ret);
 
+	lockdep_set_class(&etnaviv_obj->lock, &etnaviv_prime_lock_class);
+
 	npages = size / PAGE_SIZE;
 
 	etnaviv_obj->sgt = sgt;