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From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Ben Widawsky <ben.widawsky@intel.com>,
	<linux-cxl@vger.kernel.org>,
	"Linux ACPI" <linux-acpi@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-nvdimm <linux-nvdimm@lists.01.org>,
	Linux PCI <linux-pci@vger.kernel.org>,
	Bjorn Helgaas <helgaas@kernel.org>,
	"Chris Browy <cbrowy@avery-design.com>,
	Christoph Hellwig <hch@infradead.org>,
	Dan Williams <dan.j.williams@intel.com>,
	David Hildenbrand <david@redhat.com>,
	David Rientjes" <rientjes@google.com>,
	"Jon Masters <jcm@jonmasters.org>,
	Rafael Wysocki <rafael.j.wysocki@intel.com>,
	Randy Dunlap" <rdunlap@infradead.org>,
	"John Groves (jgroves)" <jgroves@micron.com>,
	"Kelley, Sean V" <sean.v.kelley@intel.com>,
	"kernel test robot" <lkp@intel.com>,
	Dan Williams <dan.j.willams@intel.com>
Subject: Re: [PATCH v2 4/8] cxl/mem: Add basic IOCTL interface
Date: Thu, 11 Feb 2021 10:06:46 +0000	[thread overview]
Message-ID: <20210211100646.00007dcc@Huawei.com> (raw)
In-Reply-To: <CAPcyv4hRUB3jxdCV06y0kYMbKbGroEW6F9yOQ4KB_z6YgWBZ4Q@mail.gmail.com>

On Wed, 10 Feb 2021 20:40:52 -0800
Dan Williams <dan.j.williams@intel.com> wrote:

> On Wed, Feb 10, 2021 at 10:47 AM Jonathan Cameron
> <Jonathan.Cameron@huawei.com> wrote:
> [..]
> > > +#define CXL_CMDS                                                          \
> > > +     ___C(INVALID, "Invalid Command"),                                 \
> > > +     ___C(IDENTIFY, "Identify Command"),                               \
> > > +     ___C(MAX, "Last command")
> > > +
> > > +#define ___C(a, b) CXL_MEM_COMMAND_ID_##a
> > > +enum { CXL_CMDS };
> > > +
> > > +#undef ___C
> > > +#define ___C(a, b) { b }
> > > +static const struct {
> > > +     const char *name;
> > > +} cxl_command_names[] = { CXL_CMDS };
> > > +#undef ___C  
> >
> > Unless there are going to be a lot of these, I'd just write them out long hand
> > as much more readable than the macro magic.  
> 
> This macro magic isn't new to Linux it was introduced with ftrace:
> 
> See "cpp tricks and treats": https://lwn.net/Articles/383362/

Yeah. I've dealt with that one a few times. It's very cleaver and compact
but a PITA to debug build errors related to it.

> 
> >
> > enum {
> >         CXL_MEM_COMMAND_ID_INVALID,
> >         CXL_MEM_COMMAND_ID_IDENTIFY,
> >         CXL_MEM_COMMAND_ID_MAX
> > };
> >
> > static const struct {
> >         const char *name;
> > } cxl_command_names[] = {
> >         [CXL_MEM_COMMAND_ID_INVALID] = { "Invalid Command" },
> >         [CXL_MEM_COMMAND_ID_IDENTIFY] = { "Identify Comamnd" },
> >         /* I hope you never need the Last command to exist in here as that sounds like a bug */
> > };
> >
> > That's assuming I actually figured the macro fun out correctly.
> > To my mind it's worth doing this stuff for 'lots' no so much for 3.  
> 
> The list will continue to expand, and it eliminates the "did you
> remember to update cxl_command_names" review burden permanently.

How about a compromise.  Add a comment giving how the first entry expands to
avoid people (me at least :) having to think their way through it every time?

Jonathan


  reply	other threads:[~2021-02-11 10:10 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-10  0:02 [PATCH v2 0/8] CXL 2.0 Support Ben Widawsky
2021-02-10  0:02 ` [PATCH v2 1/8] cxl/mem: Introduce a driver for CXL-2.0-Type-3 endpoints Ben Widawsky
2021-02-10 16:17   ` Jonathan Cameron
2021-02-10 17:12     ` Ben Widawsky
2021-02-10 17:23       ` Jonathan Cameron
2021-02-10  0:02 ` [PATCH v2 2/8] cxl/mem: Find device capabilities Ben Widawsky
2021-02-10 13:32   ` Jonathan Cameron
2021-02-10 15:07     ` Jonathan Cameron
2021-02-10 16:55       ` Ben Widawsky
2021-02-10 17:30         ` Jonathan Cameron
2021-02-10 18:16         ` Ben Widawsky
2021-02-11  9:55           ` Jonathan Cameron
2021-02-11 15:55             ` Ben Widawsky
2021-02-12 13:27               ` Jonathan Cameron
2021-02-12 15:54                 ` Ben Widawsky
2021-02-11 18:27             ` Ben Widawsky
2021-02-12 13:23               ` Jonathan Cameron
2021-02-10 19:32     ` Ben Widawsky
2021-02-10 17:41   ` Jonathan Cameron
2021-02-10 18:53     ` Ben Widawsky
2021-02-10 19:54       ` Dan Williams
2021-02-11 10:01         ` Jonathan Cameron
2021-02-11 16:04           ` Ben Widawsky
2021-02-10  0:02 ` [PATCH v2 3/8] cxl/mem: Register CXL memX devices Ben Widawsky
2021-02-10 18:17   ` Jonathan Cameron
2021-02-11 10:17     ` Jonathan Cameron
2021-02-11 20:40       ` Dan Williams
2021-02-12 13:33         ` Jonathan Cameron
2021-02-10  0:02 ` [PATCH v2 4/8] cxl/mem: Add basic IOCTL interface Ben Widawsky
2021-02-10 18:45   ` Jonathan Cameron
2021-02-10 20:22     ` Ben Widawsky
2021-02-11  4:40     ` Dan Williams
2021-02-11 10:06       ` Jonathan Cameron [this message]
2021-02-11 16:54         ` Ben Widawsky
2021-02-14 16:30   ` Al Viro
2021-02-14 23:14     ` Ben Widawsky
2021-02-14 23:50       ` Al Viro
2021-02-14 23:57         ` Al Viro
2021-02-10  0:02 ` [PATCH v2 5/8] cxl/mem: Add a "RAW" send command Ben Widawsky
2021-02-10 15:26   ` Ariel.Sibley
2021-02-10 16:49     ` Ben Widawsky
2021-02-10 18:03       ` Ariel.Sibley
2021-02-10 18:11         ` Ben Widawsky
2021-02-10 18:46           ` Ariel.Sibley
2021-02-10 19:12             ` Ben Widawsky
2021-02-11 16:43     ` Dan Williams
2021-02-11 11:19   ` Jonathan Cameron
2021-02-11 16:01     ` Ben Widawsky
2021-02-12 13:40       ` Jonathan Cameron
2021-02-10  0:02 ` [PATCH v2 6/8] cxl/mem: Enable commands via CEL Ben Widawsky
2021-02-11 12:02   ` Jonathan Cameron
2021-02-11 17:45     ` Ben Widawsky
2021-02-11 20:34       ` Dan Williams
2021-02-16 13:43     ` Bartosz Golaszewski
2021-02-10  0:02 ` [PATCH v2 7/8] cxl/mem: Add set of informational commands Ben Widawsky
2021-02-11 12:07   ` Jonathan Cameron
2021-02-10  0:02 ` [PATCH v2 8/8] MAINTAINERS: Add maintainers of the CXL driver Ben Widawsky

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