From: "Pali Rohár" <pali.rohar@gmail.com>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>,
linux-input@vger.kernel.org, linux-bluetooth@vger.kernel.org,
Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
Enric Balletbo i Serra <enric.balletbo@collabora.com>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Logan Gunthorpe <logang@deltatee.com>,
Andrey Smirnov <andrew.smirnov@gmail.com>,
Kirill Smelkov <kirr@nexedi.com>
Subject: Re: [PATCH] Input: uinput - Add UI_SET_UNIQ ioctl handler
Date: Mon, 2 Dec 2019 09:47:50 +0100 [thread overview]
Message-ID: <20191202084750.k7lafzzrf3yq2tqs@pali> (raw)
In-Reply-To: <20191202012305.GQ248138@dtor-ws>
On Sunday 01 December 2019 17:23:05 Dmitry Torokhov wrote:
> Hi Pali,
>
> On Sun, Dec 01, 2019 at 03:53:57PM +0100, Pali Rohár wrote:
> > Hello!
> >
> > On Wednesday 27 November 2019 10:51:39 Abhishek Pandit-Subedi wrote:
> > > Support setting the uniq attribute of the input device. The uniq
> > > attribute is used as a unique identifier for the connected device.
> > >
> > > For example, uinput devices created by BlueZ will store the address of
> > > the connected device as the uniq property.
> > >
> > > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> >
> > ...
> >
> > > diff --git a/include/uapi/linux/uinput.h b/include/uapi/linux/uinput.h
> > > index c9e677e3af1d..d5b7767c1b02 100644
> > > --- a/include/uapi/linux/uinput.h
> > > +++ b/include/uapi/linux/uinput.h
> > > @@ -145,6 +145,7 @@ struct uinput_abs_setup {
> > > #define UI_SET_PHYS _IOW(UINPUT_IOCTL_BASE, 108, char*)
> > > #define UI_SET_SWBIT _IOW(UINPUT_IOCTL_BASE, 109, int)
> > > #define UI_SET_PROPBIT _IOW(UINPUT_IOCTL_BASE, 110, int)
> > > +#define UI_SET_UNIQ _IOW(UINPUT_IOCTL_BASE, 111, char*)
> >
> > I think that usage of char* as type in _IOW would cause compatibility
> > problems like it is for UI_SET_PHYS (there is UI_SET_PHYS_COMPAT). Size
> > of char* pointer depends on userspace (32 vs 64bit), so 32bit process on
> > 64bit kernel would not be able to call this new UI_SET_UNIQ ioctl.
> >
> > I would suggest to define this ioctl as e.g.:
> >
> > #define UI_SET_UNIQ _IOW(_IOC_WRITE, UINPUT_IOCTL_BASE, 111, 0)
> >
> > And then in uinput.c code handle it as:
> >
> > case UI_SET_UNIQ & ~IOCSIZE_MASK:
> >
> > as part of section /* Now check variable-length commands */
>
> If we did not have UI_SET_PHYS in its current form, I'd agree with you,
> but I think there is benefit in having UI_SET_UNIQ be similar to
> UI_SET_PHYS.
I thought that ioctl is just number, so we can define it as we want. And
because uinput.c has already switch for variable-length commands it
would be easy to use it. Final handling can be in separate function like
for UI_SET_PHYS which can look like same.
> But you are absolutely correct that in current form the patch is
> deficient on 64/32 systems, and the compat handling needs to be added
> before it can be accepted.
Is not better to avoid usage of compat ioctl? Or it is OK to use compat
ioctl also for new features? I do not know if there are some kernel
rules for it or not... But for me it sounds like "compatibility layer
for older code".
--
Pali Rohár
pali.rohar@gmail.com
next prev parent reply other threads:[~2019-12-02 8:47 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-27 18:51 [PATCH] Input: uinput - Add UI_SET_UNIQ ioctl handler Abhishek Pandit-Subedi
2019-12-01 14:53 ` Pali Rohár
2019-12-02 1:23 ` Dmitry Torokhov
2019-12-02 8:47 ` Pali Rohár [this message]
2019-12-02 17:54 ` Dmitry Torokhov
2019-12-02 18:53 ` Pali Rohár
2019-12-02 19:36 ` Dmitry Torokhov
2019-12-02 22:54 ` Abhishek Pandit-Subedi
2019-12-02 23:09 ` Pali Rohár
2019-12-03 17:38 ` Pali Rohár
2019-12-03 19:11 ` Dmitry Torokhov
2019-12-04 12:02 ` Luiz Augusto von Dentz
2019-12-04 21:59 ` Abhishek Pandit-Subedi
2019-12-05 10:52 ` Pali Rohár
2019-12-05 20:03 ` Abhishek Pandit-Subedi
2019-12-06 9:11 ` Pali Rohár
2019-12-06 17:40 ` Dmitry Torokhov
2019-12-16 21:57 ` Abhishek Pandit-Subedi
2019-12-18 11:02 ` Pali Rohár
2019-12-18 11:26 ` Pali Rohár
2020-03-22 15:47 ` Pali Rohár
2022-06-13 21:36 ` Luiz Augusto von Dentz
2024-02-06 17:17 ` Chris Morgan
2024-02-06 17:44 ` Pali Rohár
2019-12-04 1:49 ` Marcel Holtmann
2022-06-29 9:31 ` macmpi
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191202084750.k7lafzzrf3yq2tqs@pali \
--to=pali.rohar@gmail.com \
--cc=abhishekpandit@chromium.org \
--cc=andrew.smirnov@gmail.com \
--cc=dmitry.torokhov@gmail.com \
--cc=enric.balletbo@collabora.com \
--cc=kirr@nexedi.com \
--cc=linux-bluetooth@vger.kernel.org \
--cc=linux-input@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=logang@deltatee.com \
--cc=luiz.dentz@gmail.com \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).