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SubjectRe: usb-uhci + SMP -> bad
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
>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

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

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