Re: usb-uhci + SMP -> bad

[Russell Cattelan <cattelan@thebarn.com>]

Andre Pang wrote:

>On Tue, Aug 14, 2001 at 01:48:06PM +0100, Alan Cox wrote:
>
>>>	- use the uhci USB driver when I'm using a USB printer.  If I
>>>	  use the usb-uhci driver with my USB printer, the whole system
>>>	  locks.  This has been reported a few times on LKML,
>>>	  linux-usb-users, and linux-usb-developers and nobody helped,
>>>	  but a few people wrote back with "me too"s.  It was broken in
>>>	  the trasnition from 2.4.3 to 2.4.4 and only seems to affect
>>>	  SMP systems.  I just gave up on USB printing and went back to
>>>	  my parallel port.
>>>
>>usb-uhci seems to not be SMP safe. Ultimately we don't need both uhci
>>drivers so that hasnt been one that worried me.  Probably we should drop
>>the other uhci driver over time (2.5 maybe)
>>
>
>i'd just thought i'd verify that usb-uchi seems to be causing
>some havoc on SMP boxes.
>
>i've had complete crashes (Alt-SysRq-s doesn't respond) when i
>try to print stuff to a USB printer using the usb-uchi and
>printer modules.  this is on an SMP box.
>
>however -- 2.4.2 works perfectly for that.  it broke from 2.4.4
>onward (tried 2.4.[5-7], i'm presuming .8 hasn't fixed the
>problem.)
>
>if anybody wants me to help them diagnose the problem, i'd be
>more than happy to, but i'm not sure where to start at the
>moment.
>

Note the usb sound driver does that same thing even on a UP box (with 
SMP kernel and UP kernel)

I've tried to debug the problem but setting nmi_watchdog=1 at boot time 
does seem
to catch the problem so I don't have much to go on.

If you haven't set nmi_watchdog yet you may want to try it and see if 
you have
better luck.

And yes comfirmed 2.4.3 works 2.4.[45678] does not.


-Russell Cattelan