crypto: scatterwalk - Hide PageSlab call to optimise away flush_dcache_page
On architectures where flush_dcache_page is not needed, we will
end up generating all the code up to the PageSlab call. This is
because PageSlab operates on a volatile pointer and thus cannot
be optimised away.
This patch works around this by checking whether flush_dcache_page
is needed before we call PageSlab which then allows PageSlab to be
compiled awy.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
index 2ef9cbb..ea5815c 100644
--- a/crypto/scatterwalk.c
+++ b/crypto/scatterwalk.c
@@ -54,7 +54,11 @@
struct page *page;
page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
- if (!PageSlab(page))
+ /* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as
+ * PageSlab cannot be optimised away per se due to
+ * use of volatile pointer.
+ */
+ if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page))
flush_dcache_page(page);
}