From: "Jan Beulich" <JBeulich@novell.com>
To: George Dunlap <George.Dunlap@eu.citrix.com>
Cc: Christoph Egger <Christoph.Egger@amd.com>,
"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
Subject: Re: regression from c/s 22071:c5aed2e049bc (ept: Put locks around ept_get_entry) ?
Date: Thu, 16 Dec 2010 15:51:36 +0000 [thread overview]
Message-ID: <4D0A439802000078000286FC@vpn.id2.novell.com> (raw)
In-Reply-To: <AANLkTikB5ym067GQOj4pCJCx3egjki20Guj-_Z67Tcis@mail.gmail.com>
>>> On 14.12.10 at 11:47, George Dunlap <George.Dunlap@eu.citrix.com> wrote:
> Attached is a ported patch that removes locking in ept_get_entry(),
> and implements access-once semantics for reading and writing. This
> solves the original problem (a race between reading and writing the
> table) without causing deadlocks. I haven't had a chance to test it
> -- can you give it a spin?
I think this is missing some barrier() instances (or volatile
qualifiers). Without them, I don't think there's a guarantee
that the single memory access in the source won't be
converted to multiple ones at the compiler's discretion.
Jan
next prev parent reply other threads:[~2010-12-16 15:51 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-14 8:39 regression from c/s 22071:c5aed2e049bc (ept: Put locks around ept_get_entry) ? Jan Beulich
2010-12-14 10:47 ` George Dunlap
2010-12-14 10:48 ` George Dunlap
2010-12-14 12:37 ` Jan Beulich
2010-12-14 14:32 ` George Dunlap
2010-12-14 14:34 ` George Dunlap
2010-12-14 14:50 ` Jan Beulich
2010-12-16 15:51 ` Jan Beulich [this message]
2010-12-16 16:12 ` Keir Fraser
2010-12-16 16:22 ` Jan Beulich
2010-12-16 16:42 ` Keir Fraser
2010-12-16 16:50 ` Jan Beulich
2010-12-16 17:03 ` Keir Fraser
2010-12-16 20:34 ` Keir Fraser
2010-12-17 11:15 ` Tim Deegan
2010-12-20 16:24 ` George Dunlap
2010-12-17 14:03 ` Olaf Hering
2010-12-17 14:18 ` Keir Fraser
2010-12-16 16:59 ` Keir Fraser
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