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

Geert Uytterhoeven
2007-07-16T14:59:31Z

[-- Attachment #1: Type: TEXT/PLAIN, Size: 2132 bytes --]

On Mon, 16 Jul 2007, Jens Axboe wrote:
> On Mon, Jul 16 2007, James Bottomley wrote:
> > On Mon, 2007-07-16 at 14:16 +0200, Jens Axboe wrote:
> > > On Mon, Jul 16 2007, Geert Uytterhoeven wrote:
> > > > On Fri, 13 Jul 2007, Geert Uytterhoeven wrote:
> > > > > 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.
> > >
> > > > - 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

Sony Network and Software Technology Center Europe
The Corporate Village · Da Vincilaan 7-D1 · B-1935 Zaventem · Belgium

Phone: +32 (0)2 700 8453
Fax: +32 (0)2 700 8622
E-mail: Geert.Uytterhoeven@sonycom.com
Internet: http://www.sony-europe.com/

Sony Network and Software Technology Center Europe
A division of Sony Service Centre (Europe) N.V.
Registered office: Technologielaan 7 · B-1840 Londerzeel · Belgium
VAT BE 0413.825.160 · RPR Brussels
Fortis Bank Zaventem · Swift GEBABEBB08A · IBAN BE39001382358619