crypto: scatterwalk - Hide PageSlab call to optimise away flush_dcache_page

[firefly-linux-kernel-4.4.55.git] / crypto / scatterwalk.c

diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
index 2ef9cbbc5dbf326904bac71359e559402b1cd35b..ea5815c5e12817912e1749d6aaf1a84606d7e7f3 100644 (file)
--- a/crypto/scatterwalk.c
+++ b/crypto/scatterwalk.c
@@ -54,7 +54,11 @@ static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
                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);
        }