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Re: [Xen-devel] xenbus_dev_write and failed writes

To: Keir Fraser <keir@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] xenbus_dev_write and failed writes
From: John Levon <levon@xxxxxxxxxxxxxxxxx>
Date: Fri, 2 Mar 2007 16:35:35 +0000
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On Fri, Mar 02, 2007 at 04:26:22PM +0000, Keir Fraser wrote:

> On 2/3/07 16:06, "John Levon" <levon@xxxxxxxxxxxxxxxxx> wrote:
> > In several places after setting u->len we return directly on error.
> > Apart from the partial write case, it seems all of these should be
> > resetting u->len to 0 as happens in the success case?
> Indeed. Now fixed (along with a couple of other bugs in that function).

Also, the BUG_ON in xenbusdrv_queue_reply() looks odd to me (in fact the
whole function does). Are we really guaranteed that a reply message will
be less than a page size? And it doesn't seem right to just stomp on the
buffer contents if we wrap right past the consumer value.

We've seen both the BUG_ON (well, the ASSERT) and "xenstore-ls /" hang.
Looking into exactly why now...


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