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

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Date:   Mon, 28 Jan 2019 17:04:28 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     linux-kernel@...r.kernel.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 Mon, Jan 28, 2019 at 10:55:13PM +0900, Masami Hiramatsu wrote:
> Hi Greg,
> 
> On Thu, 24 Jan 2019 11:26:52 +0900
> Masami Hiramatsu <mhiramat@...nel.org> wrote:
> 
> > On Wed, 23 Jan 2019 11:28:14 +0100
> > Greg Kroah-Hartman <gregkh@...uxfoundation.org> 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.
> > 
> > With Greg's return check removal patches, I'm OK for this change.
> > 
> > Reviewed-by: Masami Hiramatsu <mhiramat@...nel.org>
> > 
> > Thank you,
> > 
> > > 
> > > 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>
> > > Cc: stable <stable@...r.kernel.org>
> 
> BTW, would you really think it should go to stable? It seems an improvement
> instead of a bugfix...

See later in the thread, I decided that was not the correct thing to do
:)

thanks,

greg k-h