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From: Arnd Bergmann <arnd@arndb.de>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Darren Hart <dvhart@infradead.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
	gregkh <gregkh@linuxfoundation.org>,
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	qat-linux@intel.com,
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Subject: Re: [PATCH v2 05/17] compat_ioctl: move more drivers to generic_compat_ioctl_ptrarg
Date: Mon, 24 Sep 2018 23:17:01 +0200	[thread overview]
Message-ID: <CAK8P3a1Bh9NnncbcT0X4fKWC7B0FnqYyEMUwB6MvmzaNO7VhFQ@mail.gmail.com> (raw)
In-Reply-To: <20180924203505.GC6008@ziepe.ca>

On Mon, Sep 24, 2018 at 10:35 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> On Mon, Sep 24, 2018 at 10:18:52PM +0200, Arnd Bergmann wrote:
> > On Tue, Sep 18, 2018 at 7:59 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> > > On Tue, Sep 18, 2018 at 10:51:08AM -0700, Darren Hart wrote:
> > > > On Fri, Sep 14, 2018 at 09:57:48PM +0100, Al Viro wrote:
> > > > > On Fri, Sep 14, 2018 at 01:35:06PM -0700, Darren Hart wrote:
> > We already do this inside of some subsystems, notably drivers/media/,
> > and it simplifies the implementation of the ioctl handler function
> > significantly. We obviously cannot do this in general, both because of
> > traditional drivers that have 16-bit command codes (drivers/tty and others)
> > and also because of drivers that by accident defined the commands
> > incorrectly and use the wrong type or the wrong direction in the
> > definition.
>
> That could work well, but the first idea could be done globally and
> mechanically, while this would require very careful per-driver
> investigation.
>
> Particularly if the core code has worse performance.. ie due to
> kmalloc calls or something.
>
> I think it would make more sense to start by having the core do the
> case to __user and then add another entry point to have the core do
> the copy_from_user, and so on.

Having six separate callback pointers to implement a single
system call seems a bit excessive though.

        Arnd

  reply	other threads:[~2018-09-24 21:17 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-12 15:01 [PATCH v2 01/17] compat_ioctl: add generic_compat_ioctl_ptrarg() Arnd Bergmann
2018-09-12 15:01 ` [PATCH v2 02/17] compat_ioctl: move drivers to generic_compat_ioctl_ptrarg Arnd Bergmann
2018-09-12 15:33   ` Jason Gunthorpe
2018-09-12 16:20     ` Arnd Bergmann
2018-09-12 18:13   ` Greg Kroah-Hartman
2018-09-16 19:07   ` Jarkko Sakkinen
2018-09-12 15:01 ` [PATCH v2 03/17] compat_ioctl: use correct compat_ptr() translation in drivers Arnd Bergmann
2018-09-12 18:13   ` Greg Kroah-Hartman
2018-09-13  0:48   ` Andrew Donnellan
2018-09-13 11:03   ` Felipe Balbi
2018-09-12 15:01 ` [PATCH v2 04/17] ceph: fix compat_ioctl for ceph_dir_operations Arnd Bergmann
2018-09-12 16:12   ` David Laight
2018-09-12 16:25     ` Arnd Bergmann
2018-09-13  0:48   ` Yan, Zheng
2018-09-12 15:08 ` [PATCH v2 05/17] compat_ioctl: move more drivers to generic_compat_ioctl_ptrarg Arnd Bergmann
2018-09-12 15:08   ` [PATCH v2 06/17] compat_ioctl: move rtc handling into rtc-dev.c Arnd Bergmann
2018-09-12 20:00     ` Alexandre Belloni
2018-09-12 15:08   ` [PATCH v2 07/17] compat_ioctl: move tape handling into drivers Arnd Bergmann
2018-09-12 15:08   ` [PATCH v2 08/17] compat_ioctl: remove keyboard ioctl translation Arnd Bergmann
2018-09-12 15:08   ` [PATCH v2 09/17] compat_ioctl: remove HIDIO translation Arnd Bergmann
2018-09-12 15:56   ` [PATCH v2 05/17] compat_ioctl: move more drivers to generic_compat_ioctl_ptrarg Jason Gunthorpe
2018-09-12 15:58   ` Daniel Vetter
2018-09-12 16:01   ` Mauro Carvalho Chehab
2018-09-12 18:13   ` Greg Kroah-Hartman
2018-09-14 14:23   ` David Sterba
2018-09-14 20:35   ` Darren Hart
2018-09-14 20:57     ` Al Viro
2018-09-18 17:51       ` Darren Hart
2018-09-18 17:59         ` Jason Gunthorpe
2018-09-24 20:18           ` Arnd Bergmann
2018-09-24 20:35             ` Jason Gunthorpe
2018-09-24 21:17               ` Arnd Bergmann [this message]
2018-09-17  9:33   ` Jonathan Cameron
2018-10-06  7:05   ` Bjorn Andersson
2018-09-12 15:13 ` [PATCH v2 10/17] compat_ioctl: remove translation for sound ioctls Arnd Bergmann
2018-09-12 15:13   ` [PATCH v2 11/17] compat_ioctl: remove isdn ioctl translation Arnd Bergmann
2018-09-12 15:13   ` [PATCH v2 12/17] compat_ioctl: remove IGNORE_IOCTL() Arnd Bergmann
2018-09-12 15:13   ` [PATCH v2 13/17] compat_ioctl: remove /dev/random commands Arnd Bergmann
2018-09-12 18:13     ` Greg Kroah-Hartman
2018-09-12 15:13   ` [PATCH v2 14/17] compat_ioctl: remove joystick ioctl translation Arnd Bergmann
2018-09-12 15:13   ` [PATCH v2 15/17] compat_ioctl: remove PCI " Arnd Bergmann
2018-09-12 15:13   ` [PATCH v2 16/17] compat_ioctl: remove /dev/raw " Arnd Bergmann
2018-09-12 15:13   ` [PATCH v2 17/17] compat_ioctl: remove last RAID handling code Arnd Bergmann
2018-09-13 13:37   ` [PATCH v2 10/17] compat_ioctl: remove translation for sound ioctls Takashi Iwai
2018-09-13  2:07 ` [PATCH v2 01/17] compat_ioctl: add generic_compat_ioctl_ptrarg() Al Viro
2018-09-13 10:29   ` Arnd Bergmann
2018-10-28 17:07     ` Al Viro
2018-10-29  9:50       ` Arnd Bergmann

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