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Re: [Xen-devel] [PATCH] x86 spinlock: Fix memory corruption on	completing completions
 
- To: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
 
- From: Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>
 
- Date: Mon, 09 Feb 2015 18:22:21 +0530
 
- Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, kvm@xxxxxxxxxxxxxxx,	jasowang@xxxxxxxxxx, virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx,	paul.gortmaker@xxxxxxxxxxxxx, hpa@xxxxxxxxx, ak@xxxxxxxxxxxxxxx,	a.ryabinin@xxxxxxxxxxx, x86@xxxxxxxxxx, borntraeger@xxxxxxxxxx,	mingo@xxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx,	paulmck@xxxxxxxxxxxxxxxxxx, sasha.levin@xxxxxxxxxx,	davej@xxxxxxxxxx, tglx@xxxxxxxxxxxxx, waiman.long@xxxxxx,	oleg@xxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx,	pbonzini@xxxxxxxxxx, akpm@xxxxxxxxxxxxxxxxxxxx,	torvalds@xxxxxxxxxxxxxxxxxxxx
 
- Delivery-date: Mon, 09 Feb 2015 12:51:49 +0000
 
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
 
 
 
On 02/09/2015 05:32 PM, Peter Zijlstra wrote:
 
On Mon, Feb 09, 2015 at 03:04:22PM +0530, Raghavendra K T wrote:
 
So we have 3 choices,
1. xadd
2. continue with current approach.
3. a read before unlock and also after that.
 
 
For the truly paranoid we have probe_kernel_address(), suppose the lock
was in module space and the module just got unloaded under us.
 
 
Thanks.. Good idea, How costly is it?
atleast we could do probe_kernel_address() and check the value of
slowpath flag if people as us to address invalid read problem.
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