Linus Torvalds <[email protected]> wrote:
>
> There's a flush_dcache_range() thing too, but I don't see a single use
> of that function in generic code, so I suspect that one is currently
> purely for architecture-specific drivers and doesn't work in egneral.
>
> So *this* is the kind of "bad in a different way" I could imagine:
> things that probably should be cleaned up and be available to generic
> code, but very few people have cared, and so they are used in ad-hoc
> places and haven't been sufficiently generalized and cleaned up.
There is no fallback implementation of flush_dcache_range for the
architectures that don't need it.
It would be nice to have that, as doing it by hand is pretty silly:
static inline void scatterwalk_done_dst(struct scatter_walk *walk,
unsigned int nbytes)
{
scatterwalk_unmap(walk);
/*
* Explicitly check ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE instead of just
* relying on flush_dcache_page() being a no-op when not implemented,
* since otherwise the BUG_ON in sg_page() does not get optimized out.
* This also avoids having to consider whether the loop would get
* reliably optimized out or not.
*/
if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE) {
struct page *base_page;
unsigned int offset;
int start, end, i;
base_page = sg_page(walk->sg);
offset = walk->offset;
start = offset >> PAGE_SHIFT;
end = start + (nbytes >> PAGE_SHIFT);
end += (offset_in_page(offset) + offset_in_page(nbytes) +
PAGE_SIZE - 1) >> PAGE_SHIFT;
for (i = start; i < end; i++)
flush_dcache_page(nth_page(base_page, i));
}
Cheers,
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
