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Date: Wed, 18 Jul 2012 11:50:30 -0700
From: Anton Vorontsov <anton.vorontsov@linaro.org>
To: Stephen Boyd <sboyd@codeaurora.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Kees Cook <keescook@chromium.org>, Colin Cross <ccross@android.com>,
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        Jesper Juhl <jj@chaosbits.net>, Randy Dunlap <rdunlap@xenotime.net>,
        Thomas Meyer <thomas@m3y3r.de>,
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Subject: Re: [PATCH] pstore/ftrace: Convert to its own enable/disable debugfs
 knob
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On Wed, Jul 18, 2012 at 10:12:44AM -0700, Stephen Boyd wrote:
> On 07/17/12 20:47, Anton Vorontsov wrote:
> > +
> > +	file = debugfs_create_file("record_ftrace", 0600, dir, NULL,
> > +				   &pstore_knob_fops);
> > +	if (IS_ERR_OR_NULL(file)) {
> > +		err = PTR_ERR(file);
> > +		pr_err("%s: unable to create pstore/ftrace file: %d\n",
> > +		       __func__, err);
> > +		goto err_file;
> > +	}
> 
> debugfs only returns NULL on failure.

Well, techincally, with DEBUG_FS=y, yes. (And we have dependency on
it.)

But see include/linux/debugfs.h for DEBUG_FS=n case:

static inline struct dentry *debugfs_create_file(const char *name, umode_t mode,
                                        struct dentry *parent, void *data,
                                        const struct file_operations *fops)
{
        return ERR_PTR(-ENODEV);
}

So, I think it is fine to check for IS_ERR_OR_NULL(), although today
it's always NULL for our case, true.

Thanks,

-- 
Anton Vorontsov
Email: cbouatmailru@gmail.com