linux-kernel - Re: [PATCH v2] Input: evdev - Add EVIOC mechanism to extract the MT slot state

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 06 Jan 2012 11:34:06 -0800
From:	Chase Douglas <chase.douglas@...onical.com>
To:	Henrik Rydberg <rydberg@...omail.se>
CC:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Benjamin Tissoires <benjamin.tissoires@...il.com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] Input: evdev - Add EVIOC mechanism to extract the
 MT slot state

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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/