Messages in this thread | | | Date | Sun, 6 Jun 2004 21:34:02 +0200 | From | Vojtech Pavlik <> | Subject | Re: locking in psmouse |
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On Sun, Jun 06, 2004 at 08:51:59PM +0200, Pavel Machek wrote: > Hi! > > > > > > > psmouse-base.c does not have any locking. For example psmouse_command > > > > > > could race with data coming from the mouse, resulting in problem. This > > > > > > should fix it. > > > > > > > > > > Although I am not arguing that locking might be needed in psmouse module I > > > > > am somewhat confused how it will help in case of data stream coming from the > > > > > mouse... If mouse sent a byte before the kernel issue a command then it will > > > > > be delivered by KBC controller and will be processed by the interrupt handler, > > > > > probably messing up detection process. That's why as soon as we decide that > > > > > the device behind PS/2 port is some kind of mouse we disable the stream mode. > > > > > > > > Does that mean that mouse can not talk while we are sending commands > > > > to it? That would help a bit. > > > > > > > > > > Yes, check psmouse_probe. As soon as PSMOUSE_CMD_RESET_DIS acknowledged mouse > > > should cease sending motion data. That still leaves possibility of screwing up > > > detection if you are moving mouse while psmouse doing PSMOUSE_CMD_GETID. > > > But I don't think we can do much about it as we'd like to know that the device > > > is some kind of a mouse before we start messing with it. > > > > I've updated the atkbd_command/atkbd_interrupt mechanism so that even > > bytes coming from the keyboard when we're issuing a command shouldn't > > disturb us. I've tested by banging my head at the keyboard while > > plugging it in. ;) > > > > Something like that might be worth implementing for psmouse as well. > > Well, psmouse case should be just converting int foo:1 into > set_bit(&flags, BIT_FOO), no?
Not that easy. It wasn't as easy for atkbd either. This isn't just a case of locking - it's making sure you always know whether the next byte is data from the keyboard/mouse or a command response.
Only after getting the first ACK you can be sure that the keyboard/mouse will not be sending any scancodes/movement data.
> But I guess autorepeat and higher layers of keyboard might be > "interesting".
We'll get there ...
-- Vojtech Pavlik SuSE Labs, SuSE CR - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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