IB/uverbs: Add an ib_uobject getter to ioctl() infrastructure

Previously, the user had to dig inside the attribute to get the uobject.
Add a helper function that correctly extract it (and do the required
checks) for him/her.

Signed-off-by: Matan Barak <[e-mail]>
Reviewed-by: Michael J. Ruhl <[e-mail]>
Signed-off-by: Leon Romanovsky <[e-mail]>
Signed-off-by: Jason Gunthorpe <[e-mail]>

drivers/infiniband/core/uverbs_std_types_cq.c

···
 	struct ib_cq_init_attr attr = {};
 	struct ib_cq                   *cq;
 	struct ib_uverbs_completion_event_file    *ev_file = NULL;
-	const struct uverbs_attr *ev_file_attr;
 	struct ib_uobject *ev_file_uobj;
 
 	if (!(ib_dev->uverbs_cmd_mask & 1ULL << IB_USER_VERBS_CMD_CREATE_CQ))
···
 						UVERBS_ATTR_CREATE_CQ_FLAGS)))
 		return -EFAULT;
 
-	ev_file_attr = uverbs_attr_get(attrs, UVERBS_ATTR_CREATE_CQ_COMP_CHANNEL);
-	if (!IS_ERR(ev_file_attr)) {
-		ev_file_uobj = ev_file_attr->obj_attr.uobject;
-
+	ev_file_uobj = uverbs_attr_get_uobject(attrs, UVERBS_ATTR_CREATE_CQ_COMP_CHANNEL);
+	if (!IS_ERR(ev_file_uobj)) {
 		ev_file = container_of(ev_file_uobj,
 				       struct ib_uverbs_completion_event_file,
 				       uobj_file.uobj);
···
 		goto err_event_file;
 	}
 
-	obj = container_of(uverbs_attr_get(attrs,
-					   UVERBS_ATTR_CREATE_CQ_HANDLE)->obj_attr.uobject,
+	obj = container_of(uverbs_attr_get_uobject(attrs,
+						   UVERBS_ATTR_CREATE_CQ_HANDLE),
 			   typeof(*obj), uobject);
 	obj->uverbs_file	   = ucontext->ufile;
 	obj->comp_events_reported  = 0;
···
 						    struct ib_uverbs_file *file,
 						    struct uverbs_attr_bundle *attrs)
 {
-	struct ib_uverbs_destroy_cq_resp resp;
 	struct ib_uobject *uobj =
-		uverbs_attr_get(attrs, UVERBS_ATTR_DESTROY_CQ_HANDLE)->obj_attr.uobject;
-	struct ib_ucq_object *obj = container_of(uobj, struct ib_ucq_object,
-						 uobject);
+		uverbs_attr_get_uobject(attrs, UVERBS_ATTR_DESTROY_CQ_HANDLE);
+	struct ib_uverbs_destroy_cq_resp resp;
+	struct ib_ucq_object *obj;
 	int ret;
+
+	if (IS_ERR(uobj))
+		return PTR_ERR(uobj);
+
+	obj = container_of(uobj, struct ib_ucq_object, uobject);
 
 	if (!(ib_dev->uverbs_cmd_mask & 1ULL << IB_USER_VERBS_CMD_DESTROY_CQ))
 		return -EOPNOTSUPP;

drivers/infiniband/core/uverbs_std_types_flow_action.c

···
 		return ret;
 
 	/* No need to check as this attribute is marked as MANDATORY */
-	uobj = uverbs_attr_get(attrs, UVERBS_ATTR_FLOW_ACTION_ESP_HANDLE)->obj_attr.uobject;
+	uobj = uverbs_attr_get_uobject(attrs, UVERBS_ATTR_FLOW_ACTION_ESP_HANDLE);
 	action = ib_dev->create_flow_action_esp(ib_dev, &esp_attr.hdr, attrs);
 	if (IS_ERR(action))
 		return PTR_ERR(action);
···
 	if (ret)
 		return ret;
 
-	uobj = uverbs_attr_get(attrs, UVERBS_ATTR_FLOW_ACTION_ESP_HANDLE)->obj_attr.uobject;
+	uobj = uverbs_attr_get_uobject(attrs, UVERBS_ATTR_FLOW_ACTION_ESP_HANDLE);
 	action = uobj->object;
 
 	if (action->type != IB_FLOW_ACTION_ESP)

include/rdma/uverbs_ioctl.h

···
 	return uobj->object;
 }
 
+static inline struct ib_uobject *uverbs_attr_get_uobject(const struct uverbs_attr_bundle *attrs_bundle,
+							 u16 idx)
+{
+	const struct uverbs_attr *attr = uverbs_attr_get(attrs_bundle, idx);
+
+	if (IS_ERR(attr))
+		return ERR_CAST(attr);
+
+	return attr->obj_attr.uobject;
+}
+
 static inline int uverbs_copy_to(const struct uverbs_attr_bundle *attrs_bundle,
 				 size_t idx, const void *from, size_t size)
 {