Re: [patch 5/6] ps3: BD/DVD/CD-ROM Storage Driver

On Mon, 16 Jul 2007, Jens Axboe wrote:

On Mon, Jul 16 2007, James Bottomley wrote:

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On Mon, 2007-07-16 at 14:16 +0200, Jens Axboe wrote:

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On Mon, Jul 16 2007, Geert Uytterhoeven wrote:

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On Fri, 13 Jul 2007, Geert Uytterhoeven wrote:

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Ah, that explains it. flush_dcache_page() is used in some drivers.
I'll update my patches. Thanks for the comments!

Does this look OK?
  - Replaced KM_USER0 by KM_IRQ0 (all routines are either called from an
    interrupt handler, from .request_fn (ps3disk), or from .queuecommand
    (ps3rom))

That looks good.

quoted

  - Add a call to flush_kernel_dcache_page() in routines that write to buffers

Hmm, I would have thought a flush_dcache_page() would be more
appropriate, the backing could be page cache pages.

No ... that was the point of flush_kernel_dcache_page().  The page in
question is page cache backed and contains user mappings.  However, the
block layer has already done a flush_dcache_page() in get_user_pages()
and the user shouldn't be touching memory under I/O (unless they want
self induced aliasing problems) so we're free to assume all the user
cachelines are purged, hence all we have to do is flush the kernel alias
to bring the page up to date and make the users see it correctly.

Oh indeed, I missed the flush_dcache_page() in get_user_pages().

Good, thanks for reaching a consensus, so I can update my patch series.

With kind regards,
 
Geert Uytterhoeven
Software Architect

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