[Fwd: Re: [Xen-devel] Re: First post-xenbus-change USB patch]

[harry <harry@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Sorry, forgot to copy the list on this.

--- Begin Message ---

To:	Ewan Mellor <ewan@xxxxxxxxxxxxx>
Subject:	Re: [Xen-devel] Re: First post-xenbus-change USB patch
From:	harry <harry@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Date:	Tue, 15 Nov 2005 16:48:38 +0000
In-reply-to:	<20051115153748.GL14433@xxxxxxxxxxxxxxxxxxxxxx>
References:	<1132068201.29871.48.camel@xxxxxxxxxxxxxxxxxxxxx> <20051115153748.GL14433@xxxxxxxxxxxxxxxxxxxxxx>

On Tue, 2005-11-15 at 15:37 +0000, Ewan Mellor wrote:
> On Tue, Nov 15, 2005 at 03:23:21PM +0000, harry wrote:
> 
> > I'd like the otherend_changed entrypoint to be optional please.
> 
> No problem.  I'm sure you could whizz up a patch for us.

Patch attached for making otherend_changed optional.

Signed-off-by: Harry Butterworth butterwo@xxxxxxxxxx

> 
> > I did a quick bit of testing and managed to mount the USB key again etc
> > but had a few problems with module unload and reload.  I think I maybe
> > got hit by the unregister_watch deadlock then
> 
> Yes, we really need to address that one.  The code says 
> 
>       /* Flush any currently-executing callback, unless we are it. :-) */
> 
> (IIRC, that's the deadlock point that Rusty highlighted) but I don't really
> know what this means.  Can you shed some light here on what we ought to be
> doing?

What Rusty said was that the code only worked if you unregistered a
watch from the watch callback and that it hadn't been tested and would
deadlock if you unregistered a watch from outside a watch callback. So
what needs to be done is test to make sure it works under all
circumstances and fix if really broken.  That's all I know I'm afraid.

> 
> > after I killed the FE domain, the new xenbus code gave an error message when
> > I tried to unload and reload the BE.
> 
> Which error message?

start xend
load BE driver
xm create FE
load FE driver
kill FE domain
unload BE driver
load BE driver

error message:

xenbus_probe: talk_to_otherend on backend/usb/1/0 failed.
usb: probe of usb-1-0 failed with error -2


> 
> Cheers,
> 
> Ewan.
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
> 

otherend-optional-patch
Description: Text Data

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