Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 23 Nov 2022 19:10:49 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Jason Gunthorpe <jgg@ziepe.ca>,
        Maximilian Luz <luzmaximilian@gmail.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        linux-kernel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>,
        Stefan Richter <stefanr@s5r6.in-berlin.de>,
        Wolfram Sang <wsa@kernel.org>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Sean Young <sean@mess.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Mark Gross <markgross@kernel.org>,
        Vinod Koul <vkoul@kernel.org>,
        Bard Liao <yung-chuan.liao@linux.intel.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
        Sanyog Kale <sanyog.r.kale@intel.com>,
        Andreas Noever <andreas.noever@gmail.com>,
        Michael Jamet <michael.jamet@intel.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Yehezkel Bernat <YehezkelShB@gmail.com>,
        Jiri Slaby <jirislaby@kernel.org>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Chaitanya Kulkarni <kch@nvidia.com>,
        Ming Lei <ming.lei@redhat.com>,
        Jilin Yuan <yuanjilin@cdjrlc.com>,
        Alan Stern <stern@rowland.harvard.edu>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ira Weiny <ira.weiny@intel.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Won Chung <wonchung@google.com>, alsa-devel@alsa-project.org,
        devicetree@vger.kernel.org, linux-acpi@vger.kernel.org,
        linux-block@vger.kernel.org, linux-i2c@vger.kernel.org,
        linux-i3c@lists.infradead.org, linux-input@vger.kernel.org,
        linux-media@vger.kernel.org, linux-serial@vger.kernel.org,
        linux-usb@vger.kernel.org, linux1394-devel@lists.sourceforge.net,
        platform-driver-x86@vger.kernel.org
Subject: Re: [PATCH 3/5] driver core: make struct device_type.uevent() take a
 const *
Message-ID: <Y35iKfYf3ThdVvaR@kroah.com>
References: <20221123122523.1332370-3-gregkh@linuxfoundation.org>
 <711d5275-7e80-c00d-0cdc-0f3d52175361@gmail.com>
 <Y34hgIW8p1RlQTBB@smile.fi.intel.com>
 <97be39ed-3cea-d55a-caa6-c2652baef399@gmail.com>
 <Y34zyzdbRUdyOSkA@casper.infradead.org>
 <Y34+V2bCDdqujBDk@kroah.com>
 <Y35JfNJDppRp5bLX@ziepe.ca>
 <Y35R+/eQJYI7VaDS@kroah.com>
 <Y35YlI93UBuTfgYy@ziepe.ca>
 <Y35dMIaNYSE0Cykd@casper.infradead.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <Y35dMIaNYSE0Cykd@casper.infradead.org>
Precedence: bulk

On Wed, Nov 23, 2022 at 05:49:36PM +0000, Matthew Wilcox wrote:
> On Wed, Nov 23, 2022 at 01:29:56PM -0400, Jason Gunthorpe wrote:
> > #define generic_container_of(in_type, in, out_type, out_member) \
> > 	_Generic(in,                                        \
> >                   const in_type *: ((const out_type *)container_of(in, out_type, out_member)),   \
> >                   in_type *: ((out_type *)container_of(in, out_type, out_member)) \
> > 		  )
> 
> There's a neat trick I found in seqlock.h:
> 
> #define generic_container_of(in_t, in, out_t, m)			\
> 	_Generic(*(in),							\
> 		const in_t: ((const out_t *)container_of(in, out_t, m)), \
> 		in_t: ((out_t *)container_of(in, out_type, m))	\
> 	)
> 
> and now it fits in 80 columns ;-)

Nice trick!  Dropping the inline functions is a bit different, let me
see if that still gives a sane error if we pass an incorrect type or
mess with the const * the wrong way.  I'll run some tests tomorrow
afternoon...

thanks,

greg k-h