linux-kernel - Re: [PATCH 2/2] debugfs: return error values, not NULL

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Message-ID: <20190123103122.GE17123@kroah.com>
Date:   Wed, 23 Jan 2019 11:31:22 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Michal Hocko <mhocko@...nel.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Gary R Hook <ghook@....com>,
        Heiko Carstens <heiko.carstens@...ibm.com>
Subject: Re: [PATCH 2/2] debugfs: return error values, not NULL

On Wed, Jan 23, 2019 at 11:29:30AM +0100, Greg Kroah-Hartman wrote:
> On Wed, Jan 23, 2019 at 11:28:14AM +0100, Greg Kroah-Hartman wrote:
> > When an error happens, debugfs should return an error pointer value, not
> > NULL.  This will prevent the totally theoretical error where a debugfs
> > call fails due to lack of memory, returning NULL, and that dentry value
> > is then passed to another debugfs call, which would end up succeeding,
> > creating a file at the root of the debugfs tree, but would then be
> > impossible to remove (because you can not remove the directory NULL).
> > 
> > So, to make everyone happy, always return errors, this makes the users
> > of debugfs much simpler (they do not have to ever check the return
> > value), and everyone can rest easy.
> > 
> > Reported-by: Masami Hiramatsu <mhiramat@...nel.org>
> > Reported-by: Ulf Hansson <ulf.hansson@...aro.org>
> > Reported-by: Gary R Hook <ghook@....com>
> > Reported-by: Heiko Carstens <heiko.carstens@...ibm.com>
> 
> Oops, also reported by:
> 	Sebastian Andrzej Siewior <bigeasy@...utronix.de>

And also reported by:
	Michal Hocko <mhocko@...nel.org>

I should have checked my inbox better...