IB/uverbs: Add helper to get array size from ptr attribute

When the parser of an ioctl command has the knowledge that a ptr attribute
in a bundle represents an array of structures, it is useful for it to know
the number of elements in the array. This is done by dividing the
attribute length with the element size.

Signed-off-by: Moni Shoua <monis@mellanox.com>
Reviewed-by: Guy Levi <guyle@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/drivers/infiniband/hw/mlx5/flow.c b/drivers/infiniband/hw/mlx5/flow.c
index b840d4eeba849cf0098f4fc9f53386ccca820c99..95cf4b9fc65dbecca01816654dfe0590ac1fc13e 100644 (file)
--- a/drivers/infiniband/hw/mlx5/flow.c
+++ b/drivers/infiniband/hw/mlx5/flow.c
@@ -331,7 +331,6 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_FLOW_ACTION_CREATE_MODIFY_HEADER)(
        struct ib_flow_action *action;
        size_t num_actions;
        void *in;
-       int len;
        int ret;
 
        if (!mlx5_ib_modify_header_supported(mdev))
@@ -339,18 +338,17 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_FLOW_ACTION_CREATE_MODIFY_HEADER)(
 
        in = uverbs_attr_get_alloced_ptr(attrs,
                MLX5_IB_ATTR_CREATE_MODIFY_HEADER_ACTIONS_PRM);
-       len = uverbs_attr_get_len(attrs,
-               MLX5_IB_ATTR_CREATE_MODIFY_HEADER_ACTIONS_PRM);
 
-       if (len % MLX5_UN_SZ_BYTES(set_action_in_add_action_in_auto))
-               return -EINVAL;
+       num_actions = uverbs_attr_ptr_get_array_size(
+               attrs, MLX5_IB_ATTR_CREATE_MODIFY_HEADER_ACTIONS_PRM,
+               MLX5_UN_SZ_BYTES(set_action_in_add_action_in_auto));
+       if (num_actions < 0)
+               return num_actions;
 
        ret = uverbs_get_const(&ft_type, attrs,
                               MLX5_IB_ATTR_CREATE_MODIFY_HEADER_FT_TYPE);
        if (ret)
                return ret;
-
-       num_actions = len / MLX5_UN_SZ_BYTES(set_action_in_add_action_in_auto),
        action = mlx5_ib_create_modify_header(mdev, ft_type, num_actions, in);
        if (IS_ERR(action))
                return PTR_ERR(action);

diff --git a/include/rdma/uverbs_ioctl.h b/include/rdma/uverbs_ioctl.h
index 839a857aa329f19cdc41142739b34256e107f897..bf07cd6336d3db63749340f84e8fa8a82916f1c1 100644 (file)
--- a/include/rdma/uverbs_ioctl.h
+++ b/include/rdma/uverbs_ioctl.h
@@ -719,6 +719,28 @@ uverbs_attr_get_len(const struct uverbs_attr_bundle *attrs_bundle, u16 idx)
        return attr->ptr_attr.len;
 }
 
+/*
+ * uverbs_attr_ptr_get_array_size() - Get array size pointer by a ptr
+ * attribute.
+ * @attrs: The attribute bundle
+ * @idx: The ID of the attribute
+ * @elem_size: The size of the element in the array
+ */
+static inline int
+uverbs_attr_ptr_get_array_size(struct uverbs_attr_bundle *attrs, u16 idx,
+                              size_t elem_size)
+{
+       int size = uverbs_attr_get_len(attrs, idx);
+
+       if (size < 0)
+               return size;
+
+       if (size % elem_size)
+               return -EINVAL;
+
+       return size / elem_size;
+}
+
 /**
  * uverbs_attr_get_uobjs_arr() - Provides array's properties for attribute for
  * UVERBS_ATTR_TYPE_IDRS_ARRAY.