Re: [Xen-devel] regression from c/s 22071:c5aed2e049bc (ept: Put locks around ept_get_entry) ?

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 14.12.10 at 11:47, George Dunlap <George.Dunlap@xxxxxxxxxxxxx> 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


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