From: Chase Douglas <chase.douglas@canonical.com>
To: Henrik Rydberg <rydberg@euromail.se>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Benjamin Tissoires <benjamin.tissoires@gmail.com>,
linux-input@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] Input: evdev - Add EVIOC mechanism to extract the MT slot state
Date: Fri, 06 Jan 2012 11:34:06 -0800 [thread overview]
Message-ID: <4F074CAE.7010205@canonical.com> (raw)
In-Reply-To: <20120106191835.GA2998@polaris.bitmath.org>
On 01/06/2012 11:18 AM, Henrik Rydberg wrote:
> On Fri, Jan 06, 2012 at 07:55:44PM +0100, Henrik Rydberg wrote:
>>> 2 different processes should be fine; the problem would be if 2 threads
>>> of the same process share the same file descriptor. So far the rest of
>>> evdev copes just fine with multiple threads using the same fd (all
>>> operations are atomic in this regard), setting ABS_MT_SLOT before
>>> fetching the state break this property.
>>
>> Are we talking about the need for a per-client mutex, or something
>> more subtle, like introducing indirect coupling between threads
>> through per-client states? The former ought to be easily remedied.
>
> Ok, maybe not to so easy after all, which probably answers my own
> question. Looks like a EVIOCGMTSLOT, taking both slot and event code
> as argument, would be the cleaner route to take. Another ioctl, how do we
> feel about that?
What's the problem with userspace locking?
-- Chase
next prev parent reply other threads:[~2012-01-06 19:32 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-06 15:16 [PATCH v2] Input: evdev - Add EVIOC mechanism to extract the MT slot state Henrik Rydberg
2012-01-06 16:25 ` Chase Douglas
2012-01-06 18:00 ` Benjamin Tissoires
2012-01-06 18:18 ` Dmitry Torokhov
2012-01-06 18:55 ` Henrik Rydberg
2012-01-06 19:18 ` Henrik Rydberg
2012-01-06 19:34 ` Chase Douglas [this message]
2012-01-06 19:48 ` Henrik Rydberg
2012-01-06 20:02 ` Dmitry Torokhov
2012-01-06 20:14 ` Henrik Rydberg
2012-01-06 20:23 ` Dmitry Torokhov
2012-01-06 20:30 ` Henrik Rydberg
2012-01-06 20:03 ` Dmitry Torokhov
2012-01-06 18:56 ` Chase Douglas
2012-01-06 19:58 ` Dmitry Torokhov
2012-01-06 20:09 ` Chase Douglas
2012-01-06 20:17 ` Dmitry Torokhov
2012-01-06 20:44 ` Chase Douglas
2012-01-06 18:45 ` Henrik Rydberg
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