linux-kernel - Re: [PATCH - mdadm] mdopen: always try create_named

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Date:   Thu, 30 Mar 2023 08:51:54 +1100
From:   "NeilBrown" <neilb@...e.de>
To:     "Xiao Ni" <xni@...hat.com>
Cc:     "Jes Sorensen" <jes@...ined-monkey.org>,
        "Mariusz Tkaczyk" <mariusz.tkaczyk@...ux.intel.com>,
        "Song Liu" <song@...nel.org>,
        "Linux regressions mailing list" <regressions@...ts.linux.dev>,
        "linux-raid" <linux-raid@...r.kernel.org>,
        "LKML" <linux-kernel@...r.kernel.org>,
        "Nikolay Kichukov" <hijacker@...um.net>
Subject: Re: [PATCH - mdadm] mdopen: always try create_named_array()

On Wed, 22 Mar 2023, NeilBrown wrote:
> On Wed, 22 Mar 2023, Xiao Ni wrote:
> 
> > 
> > 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