Re: [Xen-devel] building blktap as a module

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 16/10/06 10:48, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

> While drivers/xen/Kconfig has been changed to allow blktap to be a module,
> its Makefile doesn't and, if fixed, it needs a symbol not currently exported
> (zap_page_range). I thought I saw discussion of this on the list, but wasn't
> able to find it in the archives. So - does anyone care to fix this (i.e.
> replace
> the calls to zap_page_range() by exported functionality) or should I just
> post a patch fixing the Makefile and exporting zap_page_range?

The uses of zap_page_range look dubious to me.
 1. The one in blktap_release() - why? Standard semantics is for mmap
regions to exist beyond the closing of the mapping device. Doesn't make much
sense to do that here, but then again not really any need to explicitly
disallow it (and add extra code to enforce).
 2. Blktap_mmap() -- the mm subsystem will zap the range anyway on failure.
No need to do it in the driver.
 3. The loop unmaps the pages the proper way (unmap_grant). The
zap_page_range() here is entirely unnecessary afaics.

 -- Keir



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