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

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Date:   Mon, 11 Apr 2022 16:28:06 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Rob Herring <robh@...nel.org>, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        "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 Mon, Apr 11, 2022 at 04:50:11PM +0300, Andy Shevchenko wrote:
> 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?

Give us a chance, you sent this on friday and are asking about it first
thing Monday morning?

Please go and review other patches sent on the list to help us catch up.

greg k-h