[Xen-ia64-devel] Re: [XenPPC] Re: [Xen-devel] [PATCH] [GNTTAB] expandable grant table

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 27/2/07 00:05, "Hollis Blanchard" <hollisb@xxxxxxxxxx> wrote:

> I don't believe that's a concern, since updating
> grant_table->nr_grant_frames is the very last step in
> gnttab_grow_table(), and it will only grow.

If there's a memory barrier before the update of nr_grant_frames, explicitly
or implied, then removing the locking from add_to_physmap is fine. Otherwise
not: reading an integer is atomic, but using that as a flag to indicate
presence of other state updated under the same lock is just a little bit
suspect (but might be okay).

 -- Keir



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