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Date: Sun, 22 Nov 2009 02:36:59 +0300
From: Ilya Loginov <isloginov@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: David Woodhouse <dwmw2@infradead.org>, linux-kernel@vger.kernel.org,
       Peter Horton <phorton@bitbox.co.uk>,
       "Ed L. Cashin" <ecashin@coraid.com>, Jens Axboe <jens.axboe@oracle.com>
Subject: Re: [PATCH] mtd: fix mtd_blkdevs problem with caches on some
 architectures (2.6.31)
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> And then, in a .c file:
> 
> #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
> #error "you lose"
> #endif
> 
> and, of course:
> 
> #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
> <implement real code>
> #else
> <implement empty stubs>
> #endif
> 
> 
> This way
> 
> a) the definition site for ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE is
>    right next to the definition site for flush_dcache_page(), instead
>    of being in some random remote file and
> 
> b) people can't forget to implement ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE.
> 
> 
> Generally we prefer to avoid defining ARCH_HAS_FOO in header files and
> we prefer to control the definition in Kconfig.  But it sounds like we
> have a special case here..
> 

I agree. I think this is the best way. I will rewrite the patch.
Thank you!

-- 
Ilya Loginov <isloginov@gmail.com>