linux-kernel - Re: [RFT/PATCH] i8042: remove polling timer (v6)

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]

Message-Id: <200610292234.02487.dtor@insightbb.com>
Date:	Sun, 29 Oct 2006 22:34:00 -0500
From:	Dmitry Torokhov <dtor@...ightbb.com>
To:	Dave Neuer <mr.fred.smoothie@...ox.com>
Cc:	LKML <linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...l.org>,
	Vojtech Pavlik <vojtech@...e.cz>
Subject: Re: [RFT/PATCH] i8042: remove polling timer (v6)

On Sunday 29 October 2006 18:20, Dave Neuer wrote:
> On 8/23/06, Dmitry Torokhov <dtor@...ightbb.com> wrote:
> > Hi everyone,
> >
> > Here is another version of the patch removing polling timer from i8042
> > which is needed if we want tickless kernel. Keyboards should now work
> > on boxes that do not have mouse plugged in. PLease give it a test.
> 
>  What's the intent of this; just to allow tickless? Or is it also to
> make the i8042 driver less racy? I ask because I've applied this over
> (a modified) 2.6.18 on my Compaq Presario X1010us laptop which has
> been driving me crazy w/ Synaptics problems and keyboard problems
> (intermittent, but   frequent enough lately that I finally figured I
> needed to do something about it).
> 
> If removing raciness is part of the goal, isn't the window in
> i8042_aux_write still a problem?
> 
> 	if (port->mux == -1)
> 		retval = i8042_command(&c, I8042_CMD_AUX_SEND);
> 	else
> 		retval = i8042_command(&c, I8042_CMD_MUX_SEND + port->mux);
> 
>         /* i8042_command has re-enabled interrupts;
>            what happens if real interrupt happens here, before we call
> the ISR ourselves? */
> 
> 	i8042_interrupt(0, NULL, NULL);
> 	return retval;
> }
>

Hi Dave,

i8042_interrupt() uses spinlock to serialize access to the KBC so if real
interrupt happens before we call i8042_interrupt() manually (and it should
normally happen) it will just process the response and second i8042_interrupt()
will be just a no-op.

Sorry, freel like crap, will try re-reading and responding to the rest of
your email later...
 
-- 
Dmitry
-
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/