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From:   "NeilBrown" <neilb@suse.de>
To:     "Xiao Ni" <xni@redhat.com>
Cc:     "Jes Sorensen" <jes@trained-monkey.org>,
        "Mariusz Tkaczyk" <mariusz.tkaczyk@linux.intel.com>,
        "Song Liu" <song@kernel.org>,
        "Linux regressions mailing list" <regressions@lists.linux.dev>,
        "linux-raid" <linux-raid@vger.kernel.org>,
        "LKML" <linux-kernel@vger.kernel.org>,
        "Nikolay Kichukov" <hijacker@oldum.net>
Subject: Re: [PATCH - mdadm] mdopen: always try create_named_array()
In-reply-to: <167945548970.8008.8910680813298326328@noble.neil.brown.name>
References: <167875238571.8008.9808655454439667586@noble.neil.brown.name>,
 <CALTww2916uiO8_ViJQXutO2BPasFmiUJtfz8MxW0HKjDzwGFeQ@mail.gmail.com>,
 <167945548970.8008.8910680813298326328@noble.neil.brown.name>
Date:   Thu, 30 Mar 2023 08:51:54 +1100
Message-id: <168012671413.8106.6812573281942242445@noble.neil.brown.name>
Precedence: bulk

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