From: Olaf Hering <olaf@aepfle.de>
To: James Harper <james.harper@bendigoit.com.au>
Cc: xen-devel@lists.xensource.com, Ian Jackson <Ian.Jackson@eu.citrix.com>
Subject: Re: xenbus stress testing
Date: Fri, 18 Feb 2011 12:05:24 +0100 [thread overview]
Message-ID: <20110218110524.GA10012@aepfle.de> (raw)
In-Reply-To: <AEC6C66638C05B468B556EA548C1A77D01C556C5@trantor>
On Fri, Feb 18, James Harper wrote:
> I think I have found the error and it was probably a 1 in a million race
> so stress testing might not have helped anyway. My code went:
>
> len = min(ring->rsp_prod - ring->rsp_cons, msg_size)
>
> and the ASSERT was hit because len was > msg_size, and the only possible
> way I can ever see that happening is if ring->rsp_prod changed between
> the if in the min() and the assignment. I'm now snapshotting rsp_prod to
> a local variable at the start. Kind of embarrassing really as plenty of
> example code exists.
Why is there no lock to protect the ring accesses?
Olaf
next prev parent reply other threads:[~2011-02-18 11:05 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-17 9:01 xenbus stress testing James Harper
2011-02-17 19:06 ` Ian Jackson
2011-02-17 22:17 ` James Harper
2011-02-18 11:05 ` Olaf Hering [this message]
2011-02-18 11:43 ` Paul Durrant
2011-02-18 12:01 ` Olaf Hering
2011-02-18 12:43 ` James Harper
2011-02-18 12:25 ` Ian Jackson
2011-02-18 12:42 ` James Harper
2011-02-18 13:08 ` Keir Fraser
2011-02-18 15:30 ` Ian Jackson
2011-02-18 22:36 ` James Harper
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