RDMA/uverbs: Add a method to introspect handles in a context

Introduce a helper function gather_objects_handle() to copy object handles
under a spin lock.

Expose these objects handles via the uverbs ioctl interface.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>

drivers/infiniband/core/uverbs_std_types_device.c

@@ -51,8 +51,95 @@ DECLARE_UVERBS_NAMED_METHOD(UVERBS_METHOD_INVOKE_WRITE,
 						UA_OPTIONAL),
 			    UVERBS_ATTR_UHW());
 
+static uint32_t *
+gather_objects_handle(struct ib_uverbs_file *ufile,
+		      const struct uverbs_api_object *uapi_object,
+		      struct uverbs_attr_bundle *attrs,
+		      ssize_t out_len,
+		      u64 *total)
+{
+	u64 max_count = out_len / sizeof(u32);
+	struct ib_uobject *obj;
+	u64 count = 0;
+	u32 *handles;
+
+	/* Allocated memory that cannot page out where we gather
+	 * all object ids under a spin_lock.
+	 */
+	handles = uverbs_zalloc(attrs, out_len);
+	if (IS_ERR(handles))
+		return handles;
+
+	spin_lock_irq(&ufile->uobjects_lock);
+	list_for_each_entry(obj, &ufile->uobjects, list) {
+		u32 obj_id = obj->id;
+
+		if (obj->uapi_object != uapi_object)
+			continue;
+
+		if (count >= max_count)
+			break;
+
+		handles[count] = obj_id;
+		count++;
+	}
+	spin_unlock_irq(&ufile->uobjects_lock);
+
+	*total = count;
+	return handles;
+}
+
+static int UVERBS_HANDLER(UVERBS_METHOD_INFO_HANDLES)(
+	struct uverbs_attr_bundle *attrs)
+{
+	const struct uverbs_api_object *uapi_object;
+	ssize_t out_len;
+	u64 total = 0;
+	u16 object_id;
+	u32 *handles;
+	int ret;
+
+	out_len = uverbs_attr_get_len(attrs, UVERBS_ATTR_INFO_HANDLES_LIST);
+	if (out_len <= 0 || (out_len % sizeof(u32) != 0))
+		return -EINVAL;
+
+	ret = uverbs_get_const(&object_id, attrs, UVERBS_ATTR_INFO_OBJECT_ID);
+	if (ret)
+		return ret;
+
+	uapi_object = uapi_get_object(attrs->ufile->device->uapi, object_id);
+	if (!uapi_object)
+		return -EINVAL;
+
+	handles = gather_objects_handle(attrs->ufile, uapi_object, attrs,
+					out_len, &total);
+	if (IS_ERR(handles))
+		return PTR_ERR(handles);
+
+	ret = uverbs_copy_to(attrs, UVERBS_ATTR_INFO_HANDLES_LIST, handles,
+			     sizeof(u32) * total);
+	if (ret)
+		goto err;
+
+	ret = uverbs_copy_to(attrs, UVERBS_ATTR_INFO_TOTAL_HANDLES, &total,
+			     sizeof(total));
+err:
+	return ret;
+}
+
+DECLARE_UVERBS_NAMED_METHOD(
+	UVERBS_METHOD_INFO_HANDLES,
+	/* Also includes any device specific object ids */
+	UVERBS_ATTR_CONST_IN(UVERBS_ATTR_INFO_OBJECT_ID,
+			     enum uverbs_default_objects, UA_MANDATORY),
+	UVERBS_ATTR_PTR_OUT(UVERBS_ATTR_INFO_TOTAL_HANDLES,
+			    UVERBS_ATTR_TYPE(u32), UA_OPTIONAL),
+	UVERBS_ATTR_PTR_OUT(UVERBS_ATTR_INFO_HANDLES_LIST,
+			    UVERBS_ATTR_MIN_SIZE(sizeof(u32)), UA_OPTIONAL));
+
 DECLARE_UVERBS_GLOBAL_METHODS(UVERBS_OBJECT_DEVICE,
-			      &UVERBS_METHOD(UVERBS_METHOD_INVOKE_WRITE));
+			      &UVERBS_METHOD(UVERBS_METHOD_INVOKE_WRITE),
+			      &UVERBS_METHOD(UVERBS_METHOD_INFO_HANDLES));
 
 const struct uapi_definition uverbs_def_obj_device[] = {
 	UAPI_DEF_CHAIN_OBJ_TREE_NAMED(UVERBS_OBJECT_DEVICE),

include/uapi/rdma/ib_user_ioctl_cmds.h

@@ -65,6 +65,7 @@ enum {
 
 enum uverbs_methods_device {
 	UVERBS_METHOD_INVOKE_WRITE,
+	UVERBS_METHOD_INFO_HANDLES,
 };
 
 enum uverbs_attrs_invoke_write_cmd_attr_ids {
@@ -167,4 +168,10 @@ enum uverbs_methods_actions_counters_ops {
 	UVERBS_METHOD_COUNTERS_READ,
 };
 
+enum uverbs_attrs_info_handles_id {
+	UVERBS_ATTR_INFO_OBJECT_ID,
+	UVERBS_ATTR_INFO_TOTAL_HANDLES,
+	UVERBS_ATTR_INFO_HANDLES_LIST,
+};
+
 #endif