On Wed, 22 Mar 2023, NeilBrown wrote:

On Wed, 22 Mar 2023, Xiao Ni wrote:

quoted

Second, are there possibilities that the arguments "dev" and "name" of
function create_mddev
are null at the same time?

No.  For Build or Create, dev is never NULL.  For Assemble and
Incremental, name is never NULL.

I should clarify this a bit.  For Assemble and Incremental, "name" is
never NULL *but* it might be an empty string.
So:
	if (name && name[0] == 0)
		name = NULL;

might cause it to become NULL.  So you cannot assume there is always
either a valid "dev" or a valid "name".  "dev" might be NULL, and "name"
might be "".

NeilBrown