Re: [Xen-devel] [PATCH 04 of 12] x86/mm: Enforce lock ordering for sharing page locks

[Tim Deegan <tim@xxxxxxx>]

At 21:56 -0500 on 15 Jan (1326664584), Andres Lagar-Cavilla wrote:
>  xen/arch/x86/mm/mem_sharing.c |  91 
> ++++++++++++++++++++++++++----------------
>  xen/arch/x86/mm/mm-locks.h    |  18 ++++++++-
>  xen/include/asm-x86/mm.h      |   3 +-
>  3 files changed, 76 insertions(+), 36 deletions(-)
> 
> 
> Use the ordering constructs in mm-locks.h to enforce an order
> for the p2m and page locks in the sharing code. Applies to either
> the global sharing lock (in audit mode) or the per page locks.

Good idea, though there'a rather a lot of passing stack pointers around
now.  Given that you should only ever be taking one of these paths at a
time, and you should never be waitq'd with a lock hels, maybe you could
just have a static per-pcpu pg_lock_data struct?

Cheers,

Tim.

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