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xen-devel
[Xen-devel] Re: [PATCH 11/13] x86/ticketlock: only do kick after doing u
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To: |
Jeremy Fitzhardinge <jeremy@xxxxxxxx> |
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Subject: |
[Xen-devel] Re: [PATCH 11/13] x86/ticketlock: only do kick after doing unlock |
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From: |
Peter Zijlstra <peterz@xxxxxxxxxxxxx> |
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Date: |
Fri, 02 Sep 2011 16:49:28 +0200 |
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Cc: |
Xen Devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Marcelo Tosatti <mtosatti@xxxxxxxxxx>, Nick Piggin <npiggin@xxxxxxxxx>, KVM <kvm@xxxxxxxxxxxxxxx>, maintainers <x86@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx>, Andi Kleen <andi@xxxxxxxxxxxxxx>, Avi Kivity <avi@xxxxxxxxxx>, Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Ingo Molnar <mingo@xxxxxxx>, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>, the |
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Fri, 02 Sep 2011 07:51:10 -0700 |
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<8cd2c77886e2d3fcad8258aa62509b3b2fae5545.1314922370.git.jeremy.fitzhardinge@xxxxxxxxxx> |
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<cover.1314922370.git.jeremy.fitzhardinge@xxxxxxxxxx> <8cd2c77886e2d3fcad8258aa62509b3b2fae5545.1314922370.git.jeremy.fitzhardinge@xxxxxxxxxx> |
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On Thu, 2011-09-01 at 17:55 -0700, Jeremy Fitzhardinge wrote:
> From: Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx>
>
> We must release the lock before checking to see if the lock is in
> slowpath or else there's a potential race where the lock enters the
> slow path after the unlocker has checked the slowpath flag, but before
> it has actually unlocked.
>
> Signed-off-by: Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
Wouldn't it be much better to fold it back so that this bug never
happens when you bisect?
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- [Xen-devel] [PATCH 00/13] [PATCH RFC] Paravirtualized ticketlocks, Jeremy Fitzhardinge
- [Xen-devel] [PATCH 02/13] x86/ticketlock: collapse a layer of functions, Jeremy Fitzhardinge
- [Xen-devel] [PATCH 03/13] xen/pvticketlock: Xen implementation for PV ticket locks, Jeremy Fitzhardinge
- [Xen-devel] [PATCH 04/13] x86/pvticketlock: use callee-save for lock_spinning, Jeremy Fitzhardinge
- [Xen-devel] [PATCH 01/13] x86/spinlocks: replace pv spinlocks with pv ticketlocks, Jeremy Fitzhardinge
- [Xen-devel] [PATCH 11/13] x86/ticketlock: only do kick after doing unlock, Jeremy Fitzhardinge
- [Xen-devel] Re: [PATCH 11/13] x86/ticketlock: only do kick after doing unlock,
Peter Zijlstra <=
- [Xen-devel] [PATCH 12/13] x86/pvticketlock: make sure unlock_kick pvop call is inlined, Jeremy Fitzhardinge
- [Xen-devel] [PATCH 09/13] x86/pvticketlocks: we only need to kick if there's waiters, Jeremy Fitzhardinge
- [Xen-devel] [PATCH 05/13] x86/ticketlocks: when paravirtualizing ticket locks, increment by 2, Jeremy Fitzhardinge
- [Xen-devel] [PATCH 10/13] xen/pvticket: allow interrupts to be enabled while blocking, Jeremy Fitzhardinge
- [Xen-devel] [PATCH 08/13] xen/pvticketlock: disable interrupts while blocking, Jeremy Fitzhardinge
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