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[Xen-devel] Re: [PATCH] mem_sharing: fix race condition of nominate and unshare
- To: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
- From: Jui-Hao Chiang <juihaochiang@xxxxxxxxx>
- Date: Mon, 10 Jan 2011 12:58:31 +0800
- Cc: tinnycloud <tinnycloud@xxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
- Delivery-date: Sun, 09 Jan 2011 20:59:34 -0800
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Sorry, typo
On Mon, Jan 10, 2011 at 12:57 PM, Jui-Hao Chiang <juihaochiang@xxxxxxxxx> wrote:
Hi, Tim:
On Sat, Jan 8, 2011 at 12:09 AM, Tim Deegan <Tim.Deegan@xxxxxxxxxx> wrote:
At 06:02 +0000 on 07 Jan (1294380120), Jui-Hao Chiang wrote:
> One of the solution is to
> (a) Simply replace shr_lock with p2m_lock.
I think this is the best choice. If we find that the p2m lock is a
bottleneck we can address it later.
Just to be skeptic.
Why doesn't mfn_to_gfn() take p2m lock when querying the p2m type? Is there any quarantee that the resulting type is correct and
I mean gfn_to_mfn()
trustful?
For example:
(1) User1 query the p2m type:
mfn_to_gfn(...&p2mt);
if (p2mt == p2m_ram_rw) /* do something based on the p2m type result? */
(2) User2 modify the p2m type
p2m_lock(p2m);
set_p2m_entry(..... p2m_ram_rw);
p2m_unlock(p2m);
Thanks,
Jui-Hao
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