linux-kernel - Re: [PATCH] mm/cma_debug: Check for null tmp in cma_debugfs_add

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Date:   Thu, 21 Feb 2019 10:10:10 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Yue Hu <zbestahu@...il.com>
Cc:     Michal Hocko <mhocko@...nel.org>, akpm@...ux-foundation.org,
        rientjes@...gle.com, joe@...ches.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, huyue2@...ong.com
Subject: Re: [PATCH] mm/cma_debug: Check for null tmp in cma_debugfs_add_one()

On Thu, Feb 21, 2019 at 04:56:42PM +0800, Yue Hu wrote:
> On Thu, 21 Feb 2019 09:23:09 +0100
> Michal Hocko <mhocko@...nel.org> wrote:
> 
> > On Thu 21-02-19 12:01:30, Yue Hu wrote:
> > > From: Yue Hu <huyue2@...ong.com>
> > > 
> > > If debugfs_create_dir() failed, the following debugfs_create_file()
> > > will be meanless since it depends on non-NULL tmp dentry and it will
> > > only waste CPU resource.  
> > 
> > The file will be created in the debugfs root. But, more importantly.
> > Greg (CCed now) is working on removing the failure paths because he
> > believes they do not really matter for debugfs and they make code more
> > ugly. More importantly a check for NULL is not correct because you
> > get ERR_PTR after recent changes IIRC.
> 
> Same check logic in cma_debugfs_init(), i'm just finding they do not stay
> the same.

I have patches to fix that up as well :)

thanks,

greg k-h