Date: Sat, 20 Dec 2014 09:10:43 +0900
From: Minchan Kim <minchan@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Ganesh Mahendran <opensource.ganesh@gmail.com>, ngupta@vflare.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] mm/zsmalloc: add statistics support
Message-ID: <20141220001043.GC11975@blaptop>
References: <1418993719-14291-1-git-send-email-opensource.ganesh@gmail.com>
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 <20141219233937.GA11975@blaptop>
 <20141219154548.3aa4cc02b3322f926aa4c1d6@linux-foundation.org>
 <20141219235852.GB11975@blaptop>
 <20141219160648.5cea8a6b0c764caa6100a585@linux-foundation.org>
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On Fri, Dec 19, 2014 at 04:06:48PM -0800, Andrew Morton wrote:
> On Sat, 20 Dec 2014 08:58:52 +0900 Minchan Kim <minchan@kernel.org> wrote:
> 
> > On Fri, Dec 19, 2014 at 03:45:48PM -0800, Andrew Morton wrote:
> > > On Sat, 20 Dec 2014 08:39:37 +0900 Minchan Kim <minchan@kernel.org> wrote:
> > > 
> > > > Then, we should fix debugfs_create_dir can return errno to propagate the error
> > > > to end user who can know it was failed ENOMEM or EEXIST.
> > > 
> > > Impractical.  Every caller of every debugfs interface will need to be
> > > changed!
> > 
> > If you don't like changing of all of current caller, maybe, we can define
> > debugfs_create_dir_error and use it.
> > 
> > struct dentry *debugfs_create_dir_err(const char *name, struct dentry *parent, int *err)
> > and tweak debugfs_create_dir.
> > struct dentry *debugfs_create_dir(const char *name, struct dentry *parent, int *err)

typo.

I meant this

static struct dentry *__create_file(const char *name, umode_t mode,
                                    struct dentry *parent, void *data,
                                    const struct file_operations *fops,
				    int *err)

> > {
> > 	..
> > 	..
> > 	if (error) {
> > 		*err = error;
> > 		dentry = NULL;
> > 	}
> > }
> > 
> > Why not?
> 
> It involves rehashing a lengthy argument with Greg.

Okay. Then, Ganesh,
please add warn message about duplicaed name possibility althoug
it's unlikely as it is.

Thanks.

> 
> > > 
> > > It's really irritating and dumb.  What we're supposed to do is to
> > > optionally report the failure, then ignore it.  This patch appears to
> > > be OK in that respect.
> > 
> > At least, we should notify to the user why it was failed so he can fix
> > the name if it was duplicated. So if you don't want debugfs, at least
> > I want to warn all of reasons it can fail(at least, duplicated name)
> > to the user.
> 
> Sure.  The debugfs interface design is mistaken.
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