Re: khbud stuck in D state

[Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>]

On Mon, 19 Nov 2007, Pete Zaitcev wrote:

> Coincidently, I'm working on a situation like that in OHCI (since May!).
> For some reason Sun x4100/x4200, AMD 8111, seems especially suceptible.
> It was reported on 2.6.9, but as far as I can tell, there were
> no changes which could address it since then. The tell-tale sign
> is the "bad entry" message, when a TD is not found in the hash.
> It is replaced by "no hash" these days, and relegated to debug-only.
> 
> After examining the code, I think that ohci_dbg was a bad idea.
> When the "no hash" situation occurs, we may have an unfixable hard
> hang for an URB (because the list processing is abandoned when this
> happens and thus all completed TDs behind the lost one are also lost).
> This situation must not happen and we ought to keep tabs on it. We
> should bump the "no hash" message up to a normal printk with KERN_ERR.

There was a discussion, some months ago, about a bug in OHCI whereby
some TDs never made it onto the done list:

	http://marc.info/?t=117770140200003&r=1&w=2

And then what about this message?  Nobody seems to be paying any 
attention to it:

	http://marc.info/?l=linux-usb-users&m=119280375900818&w=2

Alan Stern


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