linux-kernel - Re: [PATCH v2] HID: usbhid: do not sleep when opening device

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] [day] [month] [year] [list]

Message-ID: <nycvar.YFH.7.76.2008181951490.27422@cbobk.fhfr.pm>
Date:   Tue, 18 Aug 2020 19:52:19 +0200 (CEST)
From:   Jiri Kosina <jikos@...nel.org>
To:     Johannes Hirte <johannes.hirte@...enkhaos.de>
cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        groeck@...omium.org, Nicolas Boichat <drinkcat@...omium.org>,
        linux-usb@...r.kernel.org, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] HID: usbhid: do not sleep when opening device

On Tue, 18 Aug 2020, Johannes Hirte wrote:

> > usbhid tries to give the device 50 milliseconds to drain its queues when
> > opening the device, but dies it naively by simply sleeping in open handler,
> > which slows down device probing (and thus may affect overall boot time).
> > 
> > However we do not need to sleep as we can instead mark a point of time in
> > the future when we should start processing the events.
> > 
> > Reported-by: Nicolas Boichat <drinkcat@...omium.org>
> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> > ---
> > 
> 
> This change breaks various Logitech devices: 
> https://bugzilla.kernel.org/show_bug.cgi?id=208935

Copy/pasting from the other thread:

=====
Yeah, this problem popped out also in other contexts, where many Logitech 
devices didn't probe properly, because of the race where the first IRQ is 
dropped on the floor (after hid_device_io_start() happens, but before the 
50ms timeout passess), and report descriptor never gets parsed and 
populated.

As this is just a boot time micro-optimization, I am going to revert the 
patch for 5.9 now, and we can try to fix this properly for next merge 
window.
=====

Thanks,

-- 
Jiri Kosina
SUSE Labs