linux-kernel - Re: [PATCH v6 1/5] device property: Allow error pointer to be passed to fwnode APIs

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Message-ID: <YlQyEz3/J0rb2Hew@smile.fi.intel.com>
Date:   Mon, 11 Apr 2022 16:50:11 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Rob Herring <robh@...nel.org>, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Cc:     Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Len Brown <lenb@...nel.org>,
        Nuno Sá <nuno.sa@...log.com>,
        Michael Walle <michael@...le.cc>
Subject: Re: [PATCH v6 1/5] device property: Allow error pointer to be passed
 to fwnode APIs

On Fri, Apr 08, 2022 at 09:48:40PM +0300, Andy Shevchenko wrote:
> Some of the fwnode APIs might return an error pointer instead of NULL
> or valid fwnode handle. The result of such API call may be considered
> optional and hence the test for it is usually done in a form of
> 
> 	fwnode = fwnode_find_reference(...);
> 	if (IS_ERR(fwnode))
> 		...error handling...
> 
> Nevertheless the resulting fwnode may have bumped the reference count
> and hence caller of the above API is obliged to call fwnode_handle_put().
> Since fwnode may be not valid either as NULL or error pointer the check
> has to be performed there. This approach uglifies the code and adds
> a point of making a mistake, i.e. forgetting about error point case.
> 
> To prevent this, allow an error pointer to be passed to the fwnode APIs.

Rafael and Greg, if this okay for you, can the first three patches be
applied, so we will have at least the fix in and consider constification
a further work?

-- 
With Best Regards,
Andy Shevchenko